February 29, 2012


Do calories matter?

by Peter Attia

Read Time 9 minutes

In a word, yes.  But, technically this is the wrong question.

 The correct question is probably closer to, “What is the impact of the calories I consume on my body’s ability to store fat versus burn fat?

The immediate follow-up question to some variant of this first question is, “Should I be counting calories?” In a word, no. But you’ll want to read this post fully to qualify that answer.

Before I answer these important questions, let’s spend a few moments reviewing five key concepts.

Key concept #1 – the definition of a calorie

A calorie is a unit of measurement for energy content. By formal definition a calorie is the amount of heat energy required to raise one gram of water from 14.5 to 15.5 degrees Celsius at atmospheric pressure.  One-thousand calories is equal to 1 kilocalorie, or 1 kcal for short.    Here’s where it gets a bit tricky.  Most people use the term “kilocalorie” and “calorie” interchangeably.  So when someone says, “a gram of fat has 9 calories,” they actually mean 9 kcals.   The important thing to remember is that a calorie (or kcal) tells you how much energy you get by burning the food.  Literally.  In the “old days” this is how folks figured out the energy content of food using a device called a calorimeter.  In fact, to this day this is how caloric content is measured when doing very precise measurements of food intake for rigorous scientific studies.  As a general rule carbohydrates contain between 3 and 4 kcal per gram; proteins are about the same; fats contain approximately 9 kcal per gram.

[If you’re wondering why fats contain more heat energy than carbohydrates or proteins, it has to do with the number of high energy bonds they contain. Fats are primarily made up of carbon-hydrogen and carbon-carbon bonds, which have the most stored energy.  Carbs and proteins have these bonds also but “dilute” their heat energy with less energy-dense bonds involving oxygen and nitrogen.]


Key concept #2 – thermodynamics primer

It might be a good time, if you haven’t done so recently, to give a quick skim to my previous post, revisit the causality of obesity.  In this post I review, among other things, how the First Law of Thermodynamics explains fat accumulation and loss.  To reiterate, the First Law of Thermodynamics says that the change in energy of a closed system is equal to the energy entering the system less the energy leaving the system.  When we apply this to fat accumulation, it looks like this:


People like me (and others) get a bad rap from folks who lack the patience (or training, perhaps) to actually hear the entire argument through before throwing their hands in the air, waving them frantically, and screaming that we’re violating the First Law of Thermodynamics for asserting the Alternative Hypothesis (more on this below).

Let me be as crystal clear as possible, lest anyone feel the need to accuse me of suggesting the Earth is flat.  The First Law of Thermodynamics is not being violated by anything I am about to explain, including the Alternative Hypothesis.


Key concept #3 – current dogma

Conventional wisdom, perhaps better referred to as Current Dogma, says that you gain weight because you eat more than you expend.  This is almost true!  To be 100% true, it would read: when you gain weight, it is the case that you have necessarily eaten more than you expended.   Do you see the difference? It’s subtle but very important — arguably more important than any other sentence I will write.  The first statement says over-eating caused you to get fat. The second one says if you got fat, you overate, but the possibility remains that another factor led to you to overeat.

If you believe Current Dogma, of course you’ll believe that “calories count” and that counting them (and minimizing them) is the only way to lose weight.

Key concept #4 – the rub

Most folks — but not all — who subscribe to Current Dogma do so, in part, because they don’t appreciate one very important nuance.  In the equation above, explaining the First Law of Thermodynamics, they assume the variables on the right hand of the equal sign are INDEPENDENT variables.

Let me explain the difference between independent and dependent variables for those of you trying to suppress any memories you once had of eigenvectors.  As their names suggest, independent variables can change without affecting each other, while the opposite is true for dependent variables.  A few examples, however, are worth the time to make this easy to understand.

  • The weather and my mood are dependent variables.  When the weather goes from gloomy to sunny my mood tends to improve as a result of it, and vice versa (i.e., when the weather goes from sunny to gloomy, my mood goes from good to bad). In this case the dependence is only one-way, though; my mood changing has no impact on the weather.
  • My countenance and my interaction with people are dependent variables.  When I smile it seems to cause a more positive interaction with the people around me.  Similarly, when I’m having a good interaction with someone I tend to smile more.  In this case the dependence goes both ways.
  • My height (while I was still growing) and my hair length are independent variables.  Both of these variables can change without any impact on each other.

How does this tie into the idea of the First Law? Let’s re-write the First Law with a bit more specificity:

The change in our fat mass is equal to what we eat and drink (the only source of energy entering our system) less all of the energy we expend.


Now let’s be even more specific on the “expend” part of the equation.  We expend energy in four ways: Digestion (all the energy we require to break down food, plus the undigested portions that leave our body); Exercise (everyone knows what this is, but I tend to separate it from daily activity since people really like to focus on exercise); Daily activity (the non-exercise activity we carry out); Basal expenditure (the energy we expend “underlying” any activity – e.g., when you are resting).

Let me clarify something before going further.  There are several ways to enumerate and account for our energy expenditure. I happen to do it this way, but you can do it other ways.  The important thing is to make sure that you are collectively exhaustive when doing so (and mutually exclusive if you want to make your life easier – we call this MECE, pronounced “mee-see”).

The First Law is only valid when you consider ALL of the energy entering and leaving the system (i.e., your body).


Back to the independence versus dependence issue for a moment.  If you look at the equation above, and believe the red box has no impact on the green box, and vice versa, you are saying that energy input and energy expenditure are independent variables.  However, this is not the case, and that is exactly why this problem of energy balance is so vexing.  In fact, the figure below is a more accurate representation of what is actually going on (and even this is a gross oversimplification for reasons I will mention shortly).


What you eat actually changes how you expend energy.  Similarly, how you expend energy changes what (and how) you eat.  To be even more nuanced, what you eat further impacts what you subsequently eat.  As you increase (or decrease) in size, this impacts how you expend energy.

So there are actually a whole bunch of arrows all over this diagram (I’ve only shown 2: what you eat impacting how you expend, and vice versa. If I included all of the arrows, the diagram would get out of control pretty quickly).

I’m not telling you anything you don’t already know, even though it may sound like it for a moment.  When you exercise your appetite rises relative to when you don’t exercise.  When you eat a high carb meal you are more likely to eat again sooner compared to when you eat a high fat/protein meal due to less satiety.


Key concept #5 – the Alternative Hypothesis

If, like me, you don’t subscribe to Current Dogma, you’d better at least have an alternative hypothesis for how the world works.  Here it is:

Obesity is a growth disorder just like any other growth disorder.  Specifically, obesity is a disorder of excess fat accumulation.  Fat accumulation is determined not by the balance of calories consumed and expended but by the effect of specific nutrients on the hormonal regulation of fat metabolism.  Obesity is a condition where the body prioritizes the storage of fat rather than the utilization of fat.

Why is this different from Current DogmaCurrent Dogma says it doesn’t matter what you eat, it only matters how many calories that food contains.  If you eat more calories than you expend, you gain weight.  The last part is true, but the first part is not. The Alternative Hypothesis says it DOES matter what you eat and for reasons far beyond the stored heat energy in the food (i.e., the number of calories).

Let me use an example to illustrate this.  Consider the following table of various substances known to contain a lot of stored energy.  The table shows their energy content in units we usually use to describe energy density, kilojoules per gram (middle column), and I’ve converted to units we typically only use for food energy, kcal/g or “calories” per gram, (right column). [Here we need to be very clear to distinguish between a technical calorie and a kilocalorie, which is almost always what we mean.]  A kilojoule is about 240 calories (not kilocal), so 1 kj is about 0.24 kcal, and therefore 1 kj/g is about 0.24 kcal/g.

I’ve highlighted, in bold, four rows of things we typically eat: fat (olive oil, to be specific) with about 8.9 kcal/g; ethanol with about 7.0 kcal/g; starch with about 4.1 kcal/g; and protein with about 4.0 kcal/g.

I’ve also included in this table some other substances known to contain chemical energy such as liquid fuels (e.g., gasoline, diesel, jet fuel), coal, and gunpowder.  Hard to imagine a world without these chemicals, for sure.

A quick glance of the table, which I’ve ordered from top to bottom in terms of caloric density, would suggest eating olive oil would be more “fattening” than eating starch since it contains more calories per gram, assuming you subscribe to Current Dogma.

But that same logic would also suggest eating coal would be more fattening than starch and gunpowder less fattening than ethanol.   Gasoline would be more fattening than jet fuel.  Hmmmm.  Anyone interested in testing this hypothesis (personally)?  Despite my wildest self-experiments, this is one self-experiment I’ll pass on.  Why?  Well for the same reason you’d pass on it – you know that there are far more important consequences to drinking diesel or snorting gunpowder than their relative energy densities.


Sure, everything on this list is an organic molecule largely composed of the following four atoms: carbon, hydrogen, oxygen, and nitrogen.  Not to bore everyone with a lesson on organic chemistry, but it’s the actual bonds between these atoms that are responsible for their energy densities.  When you “liberate” (i.e., break) the bond between an atom of carbon and hydrogen, for example, you release an enormous amount of stored chemical energy.  This table tells you exactly how much energy you would release if you were to break the bonds in these molecules, but that’s all it tells you.  You can’t actually know, just by looking at this table, if jet fuel is more paraffinic than diesel or if gasoline has more isomerization than propane.  And, you certainly have no idea, from the information contained in this table, of exactly how each of these substances will impact the hormones, enzymes, and cell membranes in your body if you ingest them.

Is it relevant to our bodies that olive oil has about the same energy density (i.e., calories) as biodiesel (also known as fatty-acid methyl-ester)?  Or, is it more relevant to us that consuming olive oil has a very different effect on our bodies than consuming biodiesel beyond anything to do with the calories contained within them?  Obviously consuming equal caloric amounts of olive oil versus biodiesel will have a very different impact on our body.  Why then is it so hard to appreciate or accept that equal caloric values of olive oil and rice could also have very different impacts on our body?

The upshot

Let’s get back to the question you actually want to know the answer to.  Do calories “matter”, and should you be counting them?

Energy density (calories) of food does matter, for sure, but what matters much more is what that food does in and to our bodies.  Will the calories we consume create an environment in our bodies where we want to consume more energy than we expend?  Will the calories we consume create an environment in which our bodies prefer to store excess nutrients as fat rather than mobilize fat?  These are the choices we make every time we put something in our mouth.

Our bodies are complex and dynamic systems with more feedback loops than even the most elaborate Tianhe-1A computer.  This means that two people can eat the exact same things and do the exact same amount of exercise and yet store different amounts of fat.  Does it mean they have violated the First Law of Thermodynamics?  Of course not.

Similarly, genetically identical twins can eat different macronutrient diets (i.e., differing amounts of fat, protein, carbohydrates) of the same number of calories, while doing a constant amount of exercise, and accumulate different amounts of fat.  Does this violate the First Law of Thermodynamics?  Nope.

What you eat (along with other factors, like your genetic makeup, of course) impacts how your body partitions and stores fat.  In case anyone is wondering how I got over 2,000 words into this post without mentioning the i-word, wonder no longer.  Insulin, while not the only factor involved in this process, is probably at the top of the list. When you eat foods that have the double whammy of increasing insulin levels AND increasing your cell’s resistance to insulin, your body prioritizes fat storage over fat utilization.  No one disputes that insulin is the most singularly important hormone for causing fat cells to accumulate fat.  Somehow the dispute centers on what causes people (full of billions of fat cells) to accumulate fat.

All calories are not created equally:  The energy content of food (calories) matters, but it is less important than the metabolic effect of food on our body.

Photo by Aaron Barnaby on Unsplash

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  • Michael

    Peter, thanks for the straight, clear presentation once again. I’ve started the keto journey once again following your blog. Keep up the good work.

    • Oxboy

      Dr. Attia and forum members:

      I’m 41 male and have about 30 lbs of fat to lose. Blood glucose testing all my life had always been around 85 through fat and thin.

      Went low carb/no sugar a couple of months ago and have lost 6 or 7 lbs so it’s working and I feel great.

      Had a blood draw after 12 hour fast the other day and BG was 125. Actually felt a little lightheaded during the draw, which was a first for me ever giving blood.

      Not really alarmed (yet) but just curious what’s happening with the 125 level. Is this the fat stores releasing into my blood from going primal and making the reading high? Is it less insulin in my blood? Since I was feeling a little woozy, did my muscles/liver/fat dump emergency extra glucose into my blood and spike the readings?

      Other notes:
      Triglycerides are coming down since then (from 200 to 115)
      HDL going up (from 40 to 53)

      I should mention my daily carbs hover around 75g.

      Thanks for any insight.

  • Great write Dr Peter!

    Any thoughts of signaling of food choices. More specifically, I feel better/leaner when I up my fat intake. Do you think your body is more prone to release fat-stores as if you are signaling to your body that food is plentiful no reason to store it. Hopefully you understand what I am getting at. ie…bears hibernate and what way they store more fat is by upping there intake of fruit and tubers…since fish become less plentiful in the fall.

    Thanks again for the great analysis!

  • Great post!


  • Pingback: How does the human body "burn fat"? | Easy Fatburn()

  • PK

    Another amazingly comprehensive post, Peter!

    Beyond the actual science, I prefer to sum it up very simply to those I encounter about this subject:

    It’s a LOT harder to expend more than you consume when you’re ingesting foods that just tempt you to eat more (and store more fat!) Sure, you can do it for a little while – but I’d like to see how sustainable the “feeling of constant hunger” is for you!

    So it really was a fantastic revelation for me last year to realize that the types of food I ate – actually helped me eat less and expend more.

    Thanks again.

  • Excellent post.

    Re your comment: “All calories are not created equally: The energy content of food (calories) matters, but it is less important than the metabolic effect of food on our body.”

    I think this is true both for weight maintenance and health maintenance. I do better metabolically, mentally and emotionally when I avoid foods that spike my blood sugar and insulin.

    Changing to a low carb, real food diet has exponentially increased the quality of my well being and physical health, and this, I think, is another important point to remember about food quality.

    • Absolutely, Ellen. Thanks for pointing this out. Weight is just one part of the much broader health spectrum.

  • Renee

    Another intelligent and well-written post. As a biomedical student, I find it interesting that my current educators don’t go into this sort of detail; indeed seem desperate to cling to conventional wisdom. In my last year’s organic chemistry class, the professor did not explain any significant impact on the body when saturated fats are eaten in conjuction with refined carbohydrates, only that eating saturated fats will cause you to keel over from heart disease and artheroslcerosis! When I questioned him about this, as I had been reading paleo related websites, he simply reiterated the alleged “conventional wisdom”, which does not actually appear neither conventional nor wise, as we are getting fatter and fatter! Also, cheers for keeping your website being free and non- preachy.

    • Renee, I’m glad you’ve got the courage to ask hard questions, even when they go against conventional wisdom (which once told us the Earth was flat).

      • So the Alternative Hypothesis has made no impact whatsoever on the medical establishment, obesity research community, etc? Have Low Fat proponent offered any serious response? Taubes’s book has been out for quite a while and his work must be known to all who seriously research the obesity epidemic.

        • Correct, the AH has not made much of a dent in the thinking of the medical establishment. Part of the problem is the same problem faced by Galileo and other who were ahead of their time — it takes time to turn a tanker ship. Fret not, though. NuSI is going to make this more explicit. Either we at least test the AH, or we continue down the path we’re on. Which makes more sense?

    • Chris

      Peter, how can we support NuSI?

  • Jeff

    Thank you for the explanation.

    I’ve been eating low carb, and according to ketone test strips I have been in ketosis for several weeks. I eat according to my appetite, but my weight has not dropped in two weeks.

    Is it common to plateau like this? I’d rather not start counting calories.

    • Yes, this can happen, but remember weight loss is just one component of health improvement, so be comprehensive when measuring your progress.

  • Anthony Diamond

    Great and timely article.

    I’ve been going strong on the low carb lifestyle for nearly 3 weeks now, and it’s not nearly as emotionally taxing as I thought would be. In fact, I’m enjoying it!

    However, where some important questions are now showing up are in the areas of minimum caloric requirements (and minimum protein requirements) for the body.

    Some prominent authors argue in favor of strict calorie counting not simply to warn against the effects of overeating/excessive energy in but also to discuss the effects of underconsumption/inadequate energy in. The authors suggest that there will be the following:

    1) some minimum number of calories required before the body reacts to *perceived* starvation by (among other things) slowing down the metabolism anywhere up to approximately 40% of normal function and

    2) some minimum amount of protein consumed to prevent the body from catabolizing muscle tissue AND that there is no way to prevent your body from catabolizing important organ muscle tissue rather than, say, the quadricep muscles.

    This concept, of course, is rather disconcerting and frustrating as it gets back to the suggestion (for *healthy* weight loss) for creating a energy deficit within a range, which, as Taubes put it (or at least alluded to), is not really at all possible the do accurately with current technology. One can certainly have your meals created precisely enough in a laboratory with very specific numbers of calories and macro/micronutrients, but how would one ensure he/she expends only so much energy as to remain in the narrow range of energy deficit?

    So, my two questions are:

    1. Do you agree that there might be some minimum required total calories to prevent the metabolism from significant slowing?

    2. Do you agree that there might be some minimum required total protein consumption to prevent muscle (and especially organ muscle) catabolism?

    Many thanks, Dr.


    • Anthony, thanks for your comments. Yes, there is certainly a minimum amount of caloric intake our body needs below which we can’t maintain weight. The problem, when one uses the “starvation” method to lose weight, is that you lose both lean and fat tissue (and it’s hard to gain back the lean tissue while calorie deprived), and your body compensates for the deficit buy trying to slow overall expenditure.
      Here is my take: eat when hungry and stop when not. Assuming you don’t take medication that suppress your appetite I trust that your body is smart enough to get it right. As far as protein, depending on your demands, somewhere between 1 and 2 gm/kg/day is sufficient, so make sure you’re in that ballpark.

      • Anthony Diamond

        Thank you so much. It is truly incredible that you respond to the massive number of questions with such well-thought answers.

        Kind regards,

      • RobbyG

        It’s also been my recent understanding that if there is an underlying hormonal reason for the fat deposition, a starvation diet will likely result in a person who weighs less and retains more body fat than a typical lean person (that didn’t get lean via a starvation diet).

        I recall Gary Taubes talked about both the human and animal evidence indicating such a phenomenon. The implication seems to be that the typical obese person would lose more lean mass under an unsustainable starvation diet and when they inevitably resume their old lifestyle, the hormonal dysfunction persists or is now even worse.

        I would also assume that people with functional and dysfunctional hormonal metabolisms would probably respond differently to moderate or even severe restriction.

  • Best. Post. Ever!
    Peter, so great to see that you have a blog, and I just can’t wait to say to one of my “calories count” friends, “Then I have a diet for you, ‘the gunpowder diet’…or would you be willing to entertain the notion that what you eat has effects on you beyond merely the calorie content of said food item?”

    • Chuck, I’m glad you like it, my friend. Get out there and spread the word!

  • Brad

    I’m interested in the exercise component of this as well as the dietary component. A couple of summers ago we rode our bikes from Toronto to Montreal, about 700 km; I weighed myself before the trip and after, and lost only one pound despite expending thousands more calories than I took in. In the weeks that followed, however, I lost 10 pounds while eating like a horse and getting virtually no exercise at all (I wasn’t eager to get back on the bike for a while). While the trip undoubtedly built up my leg muscles, my understanding is that the caloric benefits of muscle gain wouldn’t be significant enough to account for anywhere near that kind of weight loss over a few weeks. The feeling I had was that my body had shifted into a kind of weight-loss mode, and I would keep losing weight regardless of what I ate or whether my daily intake exceeded my daily burn rate. I experience a similar phenomenon in reverse when I do start to watch my diet and/or calories: I get the feeling that my body remains stuck in “weight gain” mode for a while and my actions have little effect, but then there’s a shift and I lose weight even if I happen to overeat for a few days. I definitely feel a lag effect between my actions and changes on the scale.

    • Brad, excellent observation. I think about this question A LOT and plan to write about it. In fact, next week’s post will touch a little on this. At the end of the ride, despite a MASSIVE caloric deficit you had effectively lost no overall weight. Why? I highly suspect that you had lost fat mass, but your BODY mass stayed constant due to water retention through a profoundly vigorous inflammatory response due to the stress of the ride. In the coming days, as the inflammation subsided the “third spacing” of fluids (that’s ICU talk for what happens when your body retains fluid due to an inflammatory response), you probably urinated more than usual (though I imagine you don’t recall this now), and your weight started to reflect the new equilibrium. These effects tend to be transient, though. There are probably other factors involved, also, such a short-term change in your insulin sensitivity. I’ll do some writing about this in the near future, I hope.

      • Michele

        Peter, As usual, thanks so much for the great post. I can’t believe this information is for free…

        Mark Sisson has pointed out the negative effects of over-traing calling it “chronic cardio”. Had you planned on doing a related post on this – overtraining and its effect on inflammation…furthermore inflammation’s effect on insulin sensitivity? (Would that be a logical cause and effect?)

        • Michele

          Sorry Peter, I had missed the part about you planning on doing more writing on the subject. I assume that it will involve the idea of “chronic cardio” and over-training.

        • Thanks so much, Michele. Training, period, leads to inflammation – so the question is how much inflammation should one tolerate (some inflammation is a very good thing; no inflammation equates to death)? I will write about this.

        • Helga

          I look forward to this post. I’m planning a long distance bike trip for this summer. I’ll probably be riding 5-10 hours per day. Some nutrition guidance would be appreciated. All the conventional wisdom says I should be eating carbs continually throughout the ride. Also if I don’t eat a ton a will “hit the wall” and be unable to perform. You seem like you’ve had some experience with endurance events. I look forward to any eating tips you might have.

          • We’ll get there in time for you. Look for next week’s post as a start.

      • Peter, I am looking forward to this future post on inflammation. I’ve been no-starch, no-grains for about 3 months now and I’ve absolutely slimmed down significantly but my weight is barely budging, maybe 2-3 lbs at most. It is mind-boggling. And in my online research, the best thing I can find is that maybe my body has replaced the fat with water as kind of a “place-holder” in the cells because it “doesn’t want to” get rid of the weight. I’m not exactly sure what this means, but I can’t find any better/other explanation. I have upped my running speed and distance somewhat and run 3-4x/week, so maybe inflammation is causing the water retention. Hopefully you can incorporate some explanation of this common “losing inches, not lbs” issue lots of low-carbers seem to experience. Thanks so much for your great posts!

        • Yes, Erica, I see this quite a bit – more so in women than men. It know it’s frustrating for people. This is one of the advantages of using DEXA scans to actually measure body composition, which is why I highly recommend them.

        • Phil

          @Helga, check out Jamie Scotts blog, http://www.thatpaleoguy.com for some great info on nutrition on the bike, particularly his high fat series.

      • Peter, you wrote, “I highly suspect that you had lost fat mass, but your BODY mass stayed constant due to water retention”.

        Despite my excellent effort at eating a high-fat, modest-protein, and very low-carb diet, after the first couple weeks, my weight loss stalled for almost a month… no, stopped, in fact.

        I reduced my use of cream, stevia, and tried to even eat less (didn’t work) to figure out what is wrong. Why am I not losing weight. But when I read the above, it really makes me wonder if I should toss out the scale (because the fat loss is working, but hidden by water), or did my ketosis just “conk out”?

        I no longer know what to believe, or if anything is really occurring, as like most people, I rely on both the scale and my belt notches to give me confirmation that I am losing weight, yet for almost a month, they have not changed, so I am left to believe I am not in ketosis, but don’t know why.

        • This is why I suggest folks get a DEXA scan. I can’t really troubleshoot in this capacity, though.

  • Lal Beral

    Thank you for this post! For the sake of drawing this out, and even though everyone’s metabolisms are a bit different, could you address this theoretical question:

    Let’s say someone is really minimizing their carb intake (even to zero) and keeps protein under control. Their insulin levels are as low as they possibly can be. They sit down and force themselves to eat many, many calories worth of fat. Let’s even say that over the course of a few days, they manage to eat, say, 17,500 calories of fat. Even if their appetite is low and they are “forcing” it down. Given that insulin is bottomed out, will they gain weight from this caloric overload?

    Maybe a simpler way of asking this is, if someone has minimized their insulin levels and they eat what would appear to be excess calories in the form of fat, will they gain or will their body find a way to waste the excess energy? At least theoretically.

    Thanks! 🙂

    • Great question. ASSUMING they can physically eat that amount of food without immediately re-expending (i.e., vomiting), they almost certainly WILL gain weight. It probably would not be as much as predicted by just the number of calories it (e.g., a lot of fat would exit in the stool), but in the end the First Law never lies. The energy needs to be accounted for somehow.

      • LalBeral

        Peter, thanks for your answer. On a related question, would you mind addressing your experiences with caloric expenditure on a very low carb diet?

        You personally eat more calories than you used to, and you have LOST weight without increasing exercise. Yet Eades on his Protein Power blog (see http://www.proteinpower.com/drmike/weight-loss/low-carb-and-calories-2/) suggests that people who want to lose weight still need to try to limit calories in order to lose, though when they reach their goal weight, they can then up calories again without gaining.

        What is your experience with yourself and others? Let’s say that someone’s typical caloric requirement is about 2,200 calories a day, and she eats that mostly through fat with adequate protein and under 15g net carbs. Could she expect to lose (albeit slowly) since insulin is under control, or does one really need to cut calories until goal weight is reached? How varied are peoples’ responses? There seems to be a lot of confusion and disagreement about this among the low-carb advisers.

        Personally, even if my carbs stay very low, I get hungry if I try to cut calories below 1900 or so.

        Thanks again! I look forward to your posts each Wednesday!

        • It’s so variable. In my experience, about a quarter to a third of folks who greatly reduce carbs (like me) actually eat much more in overall calories, but still lose weight. About a third do a eucaloric swap (i.e., eat about the same number of calories), about a third eat fewer total calories. I wish I knew WHY this happened, but I don’t.

    • Humberto

      Peter, depending on the macronutrient content of the diet, the storage of excess calories may not be possible.
      Let me know your opinion on the hypothetical scenario depicted below.

      First, some undisputed textbook biochemical concepts:

      1. The non-ketotic body needs 160 grams of carbohydrates each day: 120 grams for oxidation by the brain and 40 grams for the glycolitic tissues.
      2. In the ketotic state, the ketones can supply the brain with up to 50% of its energy expenditure .
      3. The minimal protein intake for a physically active individual would be 1 gram/kg of body weight.
      4. The molecular weight of a typical triglyceride molecule is about 850. That of glycerol is 90, which means 10% of the weight of a triglyceride molecule is glycerol.
      5. Our body cannot make glucose, nor any intermediate which ultimately leads to glucose, from fatty acids, at least not in a net sense.

      Now consider a sedentary 70 kg (154 lbs) woman. She`ll be put on a 3-day/week weightlifting program, and will be fed a diet consisting of 3960 calories/day (400 grams Fat, 70 grams Protein and 20 Grams Carbohydrate). A reasonable estimate of the total energy expenditure of a 70 kg woman would be 2700 Kcal/day on training days and 2300 Kcal on resting days. If she’ll be eating 3920 Kcal/day, that would amount to more than 1200 excess calories each day (36.000 Kcal/month). She should gain a lot of weight in the long run. Right? Let’s take a closer look.
      She’ll be eating 20 grams of carb per day, plus 40 grams of glycerol from the fat (remember, glycerol is 10% of the weight of the triglyceride molecule). That’s all the carbons (60 grams) that will be available for the production of new glucose each day, since the protein intake is exactly the amount to supply the minimum daily requirement (1 gram/kg of bodyweight). All these glucose carbons will be used for oxidation by the brain, in a net sense. The other half of the brain energetic requirement will be supplied by ketones. But, we’ll have at least 1200 Kcal/day that will have to be stored, since they will be in excess of the total energy expenditure. The fat in our body reserves is always in the form of triglycerides. The excess fat calories will have to be stored, but the fatty acids will be then, we could say, orphans, since their glycerol moiety would have been used for gluconeogenesis. There’s no way for them to be stored, unless the body uses its structural or functional protein pool to generate glucose in the liver and than glycerol in the fat cell. But if that happens, we would have a ridiculous situation, in which a sedentary 70 kg person starting a weightlifting program and eating 3920 Kcal/day would get weaker since day 1 and would eventually die of protein malnutrition, as her body would eventually use a great portion of its body protein to produce glycerol, in order to store the excess ingested calories. In the long run, the wasting of protein would become increasingly larger, since the loss of lean tissue would lower the total energy expenditure, making the amount of excess ingested calories progressively bigger. By all we know about how fiercely the body protects ist protein pool, and from practical experience, we can dismiss the above outcome as nothing but impossible.
      So what will the body do with the excess calories? It will have to burn them, and by doing so it will raise its total energy expenditure. It’s simple as that.
      In other words:
      The woman would ingest 400 grams of fat, 20 grams of carbs and 70 grams of protein each day, and approximately 133 grams of that fat would be in excess of the expenditure, and would have to be stored. But the glycerol of the fat would have been divert to the gluconeogenic pathway, and there would be no other source of carbons for glyceroneonesis besides those from the protein pool, which the body fiercely defends, and from the ingested protein, which matches exactly the amount necessary for the protein turnover.

      So we have two competing scenarios:

      1. The woman dying of protein malnutrition, despite eating 3920 Kcal/day and 1 gram/kg of bodyweight of protein. By this reasoning, if she ate less fat and less calories, she would do fine (maybe would even gain some muscle).
      2. The woman simply burning the excess calories, and not gaining a single pound of fat.

      Put that way it looks overwhelming obvious that she wouldn’t gain fat weight, perhaps because of the sheer absurdity of scenario 1. This is all common biochemical knowledge has been available for decades, and is not even disputed.
      I’d like to hear opinions on that.

      • So my intuition when I first read this was that you were over-estimating the shortage of glycerol and under-estimating the ability for re-esterification to take place. I ran the scenario you posed by Kevin Hall at NIDDK who has a robust model (it’s available on line). Model confirmed my hunch. There is no shortage of glycerol since GNG goes up and carbohydrate oxidation becomes suppressed thereby allowing enough glucose to be available for glycerol production to support the increased TG synthesis and a net positive fat balance along with positive protein balance.
        Nevertheless, a very nice thought experiment, Humberto.

    • Alan Gernet

      Hi Peter .. please can you explain the ‘fat being exited in the stool’ component above. My understanding is that the gut can absorb x amt of fat at a time. If what is absorbed is excessive and cannot be used, it ends up being stored in fat cells. Explanations that I have seen state that by eating fat more often, your gut has the opportunity to absorb more fat – meaning that x amount of fat consumed over 5 meals will allow for the absorption of more fat than what could be absorbed if consumed in 1 meal.

  • Scott

    I’d be interested to hear if you have done any in-depth research into the role of UCPs when evaluating basal expenditure. I seem to recall that putting rats on ketogenic diets causes them to emit ~15% more heat, and I was wondering if you’ve observed similar results in humans. I certainly like the idea of up-regulating UCPs so that my basal metabolism can skyrocket.

    • Scott, this information is pretty hard to come by in HUMANS with GOOD studies, because they require very rigorously controlled trials. I don’t put much faith in rat or mouse studies, even though they certainly suggest things (rats are, of course, better than mice as mice are herbivores). NuSI will be funding this exact kind of work, so please stay tuned.

  • Nick M.

    Hi Peter,
    What about for someone that has the opposite problem: I can’t seem to get past 170lbs despite a regimen of heavy weights and lots of protein/carbs. I’m 31, 5’9. Do I need to worry about carbs so much if I’m not really concerned about weight/fat gain? I thought it was about calories In, so I ate a lot of junk food and stuff trying to gain mass.

    I guess my point is….for someone that isn’t really concerned about fat gain, do we need to worry about our carb intake? I had a blood test done 2 weeks ago and my LDL-P is 367 (I take 2000mg of fish oil/day and a 5mg statin every few days).

    • Nick, take this is kindest way possible, but you’re a freak! You lucky guy! You “suffer” the same problem as my wife. You are are clearly on the far side of the carbohydrate sensitivity spectrum as demonstrated by these numbers. That LDL-P is in the bottom 1%. As one reader pointed out a few weeks ago, one drawback, perhaps, of being profoundly carb resistant (as you are) is that you may have a harder time with anabolic demands. In other words, the same thing that “protects” you from gaining fat, my inhibit you from gaining muscle. Doesn’t mean it can’t be done, of course, it’s just harder. With the right diet, the right timing of meals, and the right training, you can make gains.

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  • Fantastic post! I’ve been trying to find a way to explain this idea to people who are resistant to it, and I don’t think I could’ve come up with something so easy to grasp. I don’t know why it’s so hard for people to accept that different foods are processed differently by the body, but from now on I’ll be linking them here so they can get their minds right. Thanks so much!

    • Glad it can be of some help. It’s a very important idea, so thanks for sharing it.

  • Patrick


    Excellent post!

    The first version of your equation deals with change in “fat” mass. Should that be “body” mass? We can surely increase lean mass independent of fat mass, no?

    Second, do I take it that your list of energy expenditure also includes waste production? I’m thinking about not only about the obvious heat dissipation but also solid-waste elimination.


    • Patrick, yes, absolutely, to completely correct it would be a change in body mass. In a child, for example, this is much more important as they are gaining weight through increased bone, organ, muscle, and fat gain. However, for the point I am trying to make here (i.e., for the “average” adult), a delta in fat mass is sufficient. But thank you for pointing this out. Yes, the “energy out” includes waste, particularly stool. This is relatively easy to measure, assuming one is willing to collect it.

  • Colleen

    Peter: First, thank you so much for this very informative website and all your efforts. I discovered you and Taubes about a month ago and it has been an eyeopener to say the least. Since then, at our house we have cut way back on sugar and refined carbs and increased our fat intake. (I knew sugar was added to a lot of foods but it was a shock to see how much is in a piece of whole wheat bread). My personal experience confirms what you are addressing in the post. Almost immediately I noticed I no longer craved a “treat” at night. Some days I am not hungry at all after breakfast and lunch. Any thoughts on whether one should eat some minimum number of calories per day even if not particularly hungry? I look forward to your posts and again thanks for the excellent website.

    • Colleen, so great to hear about your evolving eating habits. I have not (yet) met someone who used hunger as their guide for eating eat too few calories (provided they were not on appetite suppressing medication). Certainly, one can eat too little for basic anabolic and cellular function, but this just doesn’t seem to be a problem for folks who eat when they are hungry and stop when they are not, PROVIDED THEY EAT THE RIGHT FOODS!

      • Peter, I’d like to add here that when in ketosis, I don’t think one has to worry about eating a minimum number of calories each day, provided, you have enough body fat.

        Once the body knows to go to your fat stores as and when it needs energy, everything changes.

  • Fred

    Great post and thanks for sharing some more information. The only part I do understand from this “Alternative Hypothesis” is what do people eat after a hard workout? I am a runner and I also mix in weights (Crossfit style), so I never know what I am suppose to drink/eat after a hard workout.

    Any assistance/ideas anyone can offer, would be great. I am a person who has struggled for many years to get his BF% down even after losing 170 lbs. The BF% is still around 28% and I think this way of eating will drive it down, but after workouts I have been “taught” to eat/drink carbs so the protein feeds the muscles, but I have yet to gain muscle or burn fat. So if I follow low carb eating style, how does my body recover from the runs?

    • Fred, this is complex question because it depends so heavily on HOW LOW carb you. Why? If you’re in ketosis like me, you do need to worry about immediately refilling glycogen stores. After long workouts I typically don’t eat much, because ketones are so high and I’m not hungry. But if you are NOT ketotic (which most people are not) do you want to get glucose and fructose in your system as soon as the workout is done. Fructose actually gets assimilated into hepatic glycogen even faster than glucose BUT the doses need to be controlled, so don’t overdo it like most people!

      • Fred

        Thanks Peter! Well I have tried being in ketosis and you are right, I am not as “hungry” after a workout, but I have always “forced” myself to eat to make sure I “fed” my muscles and to recover. Are you saying that if you are not hungry, you should not eat and it won’t effect muscle development, fat burning or recovery? When I have not been in ketosis, I usually will add a banana to my protein drink. This whole post workout thing is what has had me confused in going all out to ketosis or not. Then when I am not, I feel like my day is ruined by eating some fruit after a workout.

        • Well, it’s a bit complex. I’ll try to write about this in the (near) future. I am very particular about what I eat and when I eat it, when it comes to my training, so while I do let hunger be my guide, I am very thoughtful about how and when I supplement.

        • Fred,

          From my experience I can say a few things. Mind you, it’s an n=1 case. Like you and listened to what everyone says for years and saw no real muscle gain. Definition, yes, but that was it.

          1. Eating after working out?

          It makes no difference to me in as far as muscle build up is concerned. Intensity of your work out is what builds muscle.

          2. Eating Protein, or protein shakes etc. after working out?

          I do none of these and have been gaining muscle mass regularly.

          3. Must eat x grams of proteins each day (typically, based on body weight) or you’ll loose muscle mass?

          I don’t eat anywhere near the amount of protein I “should” be eating and yet I gain muscle mass.

          As far a gaining muscle mass is concerned, there is (I think) only one way to do it. Increase the intensity. The intensity is such that you are in agony (fight or flight) while trying to complete the last 3 repetitions. I mean real agony. Your body shakes, you’re groaning out loud or you’re screaming and you break out in a sweat even in the cold of winter. That kind of intensity. Such intensity that even in a matter of life and death you won’t be able to do yet another repetition.

          You do that and you’ll find your muscles responding daily.

          Stop all the shakes and “carbing up” stuff.

      • Birgit

        I had the same question because of moving into ketosis and then back out when I added some raw honey and fruit to help me get over a cold faster the last few days. This answer helps, I guess I’ll eat a few more carbs the day before the race and some fruit after and then try to get back to ketosis before my next race. 🙂

  • Matt

    I think the comparison of biodiesel to olive oil brought a whole new level of clarity to this line of argument. Thanks for that.

  • Matt Taylor

    Peter, I look forward to your bog every week, and this is another good post. I have a related concern that maybe you could shed a little light on. Is it possible for a person on a low-carb diet, say <50g/day, to still overeat and put on weight? I assume this is less likely than a high-carb diet, but I also would think it is possible. I don't want to cloud your post here, but have you seen this, and what might be causing it?

    • Absolutely. Check a recent comment I just responded to on this exact question.

      • Travis Koger

        I agree with this, I have been experimenting with my Fat-Protein-Carb balance in the last week and found that if I increase my protein and fat levels to above my current targets, in one case I doubled them, I absolutely put on weight. Even keeping my protein to less than 120g per day. If I maintain my balance at Fat – 80%, Protein – 15% and Carbs – 5% where Fat gram target is 200g per day, then I will definitely lose weight, typically this is 1lb per day, but on occasions it is 2lbs. Also at the moment I am trying to get my nutrition right before beginning any form of exercise as I won’t to make sure that my eating balance is right before being able to blame the exercise for the weight loss. 🙂

  • Melanie

    “If you eat more calories than you expend, you gain weight.” — Do you and Gary differ in your opinions on exercise? I have heard him say that exercise doesn’t do a darn thing for weight loss. I understand that the kinds of foods we eat matter more than a simple calories in/out equation. But if a person were eating low carb-medium protein- high fat for a couple of months and didn’t see any change in weight or inches, would you expect that an increase in exercise would cause a change in weight?

    Thank you for another informative post. I so appreciate what you’re doing.

    • Malanie, it’s a very complex issue and not one I think any of us FULLY understand. In general (i.e., for MOST people doing MOST types of exercise), exercise per se does NOT seem to lend itself to sustained weight loss, as I discuss this post. However, people who exercise are often more careful about what they eat, and this confounding factor can create a bit of confusion around the process. In controlled studies, though, it’s not clear exercise plays a meaningful role in weight loss. To your second question, it is possible, and certainly worthy of the self-experiment for someone at that plateau. I read a paper yesterday, actually, that showed IN NORMAL HEALTHY YOUNG MALES that high intensity training and an impact on insulin sensitivity. Not clear if this applies more broadly, though.

      • Greg


        I believe the exercise question as it relates to the insulin mechanism (among many mechanisms) is a complex one that we are only beginning to understand.

        On on hand it is accurate to critique exercise for how it is “sold” in the popular dogma, or as part of a calories-in, calories out equation. In other words, burning calories through exercise is trivial to say the least. What is important, as research is starting to bear out, is the longer term impact of exercise at the cellular level, to include the mechanisms related to insulin. In other words, exercise seems to increase insulin sensitivity, or stave off the negative effects of cells bathed in too much insulin over time.

        That said, carbs can easily overwhelm the capacity of exercise and its positive attributes. As has been said more than once “I’m running 6 miles a day but eating 10 miles a day” which in other words really means eating 10 miles of carbs–easy to do based on the old dogma of feeding endurance sports with a carbohydrate rich diet.

        To be honest, I agree with Gary Taubes on all aspects of his work, but I find him too dismissive of exercise. I believe a close reading of his work reveals this to be a need to expose the fallacy of the calories in/calories out calculus inherent to the pro-exercise ideology. Interestingly enough, within Lustig’s famous sugar video, the Dr. indicates that exercise in fact is quite important for various complex metabolic reasons of which he doesn’t go into during the video (as that’s not the focus). I tend to agree him–that exercise is important, but definitely not for any thermodynamic reasons.

        Great blog!

        • Thanks, Greg. I agree that exercise is important for a number of reasons, though weight loss is not on the list.

      • Debbie

        As someone maintaining a large weight loss for many years, I do believe exercise plays a role. While I am a low-carb diet believer, looking at the obesity problem from a chemical perspective only is a mistake. I think it’s important that people understand that on some level they have to deal with the behavioral aspects of overeating – for lack of a better word. Most of us are fairly addicted to delicious – carb – food, and this is why we break any diet, even the marvelous low-carb. In other words, there isn’t a magic pill; we still have to probably weather discomfort at times, maybe even a lot of discomfort. I think it sets people up for failure if they expect the low-carb diet to be painless. There’s nothing wrong with admitting to a little grief at the loss of those favorite food items that were killing us.

        • Fair point. Like I said, if exercise makes it easier to change eating habits, that’s a great thing.

      • I think it is common knowledge by now that exercise doesn’t burn many calories directly. I think this depresses people because they think that this means that exercise is useless. No so!!

        Without going into ridiculous detail, exercise does several things:

        There is an immediate non-insulin dependent glucose uptake during and immediately after exercise. This makes sense as there is no way any animal has the luxury of waiting around a few seconds for some sort of unstimulated insulin surge to kick in and deliver glucose to the muscles.

        Just after exercise there is upregulation of insulin receptors on muscle cells thereby increasing their glucose uptake even further. Additionally, the muscles are constantly metabolizing fatty acids.

        (Sorry, I’m getting ahead of myself).

        The decreased blood sugar increases glucagon and growth hormone which incites the liver to create glucose. None of this is unknown.

        The problem is people never discuss the sub cellular and organismal structural changes which accompany exercise when they dismiss exercise as useless.

        There are changes in every aspect of every cell in the body when you exercise and ESPECIALLY when you exercise habitually. Examples include: Hemoglobin synthesis is increased and there is an increased number of erythrocytes. All muscle cells increase mitochondrial density and cell hypertrophy. There is increased vascularity etc. Ligaments and tendons strengthen. Bones increase in density not only due to mineralization but due to collagen formation. The digestive system improves. There is improved sympathetic vascular tone. etc etc etc

        All of the nutrients required for these processes are removed from the fat building and maintenance equation. You convert to a different type of organism, literally.

        This isn’t to say that diet cannot sabotage the entire thing, obviously. Diet is still the most important factor by far. But I think it is unfortunate for people to look a the 150 kcal they burned off in a run and think that’s the end of it. It isn’t. It’s just the beginning.

      • Peter,

        I believe in Dr. Stephen Phinney’s book they cited a couple of studies where groups who exercised lost more weight than groups who did not even thou both groups eat the same food and same amount.

    • The intensity of exercise determines the effects. In my experience, low intensity long duration exercise (“cardio”) has very little benefit to long term fat loss. High effort strength training, sprinting, and high-intensity-interval-training DOES enhance fat loss due to depletion of glycogen stores and increased insulin sensitivity in muscle cells. Increased muscle mass from strength exercise will accelerate that rate at which fatty acids can used for fuel.

      • I think this is probably true Erick, but the data showing increased insulin sensitivity in HIT are in folks who are typically lean and already quite insulin sensitive. So I think the open (and in my opinion more important) question is, how much of an impact will this have in obese and/or insulin resistant folks. It’s certainly a plausible idea, I just haven’t seen great data suggesting it. As far as “slow” cardio, though, you’re right. Good data here suggesting that few extra calories burned during the activity are at least (if not more than) made up for in subsequent eating.
        More importantly, perhaps, is that HIT is fun and helps with all sorts of valuable activities (other sports, activities of daily living, retention of muscle mass).

        I would consider it a tragedy, however, for someone is overweight or IR to think HIT is the best first-line treatment. Fix the diet FIRST, then worry about which form of exercise.

        • You are correct; HIIT is never a good idea for de-conditioned overweight individuals (Why I hate the biggest loser). I always start beginners with resistance training using sufficient rest intervals. The results we are achieving may be due to the improved sense of well-being associated with goal oriented exercise; this may contribute more to dietary(low carb) compliance and less to improved insulin sensitivity.

        • Anthony

          Peter, your last statement here is where the fitness industry has it all wrong. The first thing they do to an overweight or obese person is make them get on a treadmill or cross trainer. Then they proceed to give them an expereince (they feel like they are going to die) that for most people will scare them into not coming back. In hindsight this is probably the best thing, but no one has mentioned the war(their diet)to them. I was a train first, nutrition later kind of man, but no more. Nutrition maketh the man, exercise finish of the good look.

        • Peter, well said. For those who are obese, Fix the diet FIRST, then worry about which form of exercise.

          On similar lines, those who are active yet overweight/obese (as I was/am) probably need to fix their diet and increase the intensity of their workouts to loose weight continuously till they reach their goals.

          I know a couple of people who have been on a ketogenic diet (Atkins induction phase) for many years and are overweight/obese. They lost some weight initially and then just stopped.

  • Steve Pehnec

    Superb article! And as an international instructor of Applied Physics, I fully approve of its content.
    Thank you, Peter!
    P.S. I’ve been following this wisdom for 16 months and am living proof that it is true.

    • Steve, thank you for your endorsement! Hopefully anyone thinking I’m suggesting the First Law doesn’t matter will read this. Good luck with your journey.

  • Michael V

    Dear Dr. Attia,

    Thank you for this website. As I’m sure many of your readers here do, I try to read a lot of the different LC/Paleo/Primal/health blogs on a daily basis. And many times I’m left shaking my head or concerned I may be making less than optimal choices.

    Can you address the issue of developing insulin resistance on a low carb or VLC diet? I thought I fixed that by going LC. Now I’m reading it may lead to IR and/or Thyroid issues.

    Having gone LC a little over a year ago, I’ve both trained and competed while in Ketosis with no impact on performance. FWIW, I compete in a power related sport, all anaerobic. What I’m reading doesn’t jibe with my personal experience, but then again I’m only a year in, maybe it’s too soon to see a problem.

    PS – If I’ve missed it on another post my apologies, but where can a person donate to this site?

    • Michael, I do plan to write about the thyroid issue, but frankly I do not know the answer right now. I do know, however, that in humans, insulin resistance is absolutely reversed (i.e., we get more insulin sensitive) with a reduction in carbohydrates.

      • Garth

        HIgh Peter,

        I’ve also seen this claim in numerous places. The idea is that, once your metabolism has switch to burning fat for fuel, you become peripherally insulin resistant, meaning your muscles and some other tissues will become insulin resistant in an effort to preserve glucose for your brain. If you then eat a big load of carbs, it takes longer for your muscles to decide to burn all of the suddenly available sugar, leading to elevated blood sugar. Of course, your body will quickly resume burning glucose after a few carb heavy meals, so it’s a short term phenomenon quite distinct from the insulin resistance caused by metabolic damage.

        • Yes, I have heard of this very transient issue, though, I’ve seen many cases to counter it (take a look at my OGTT pre- and post- low-carb): http://eatingacademy.com/how-low-carb-diet-reduced-my-risk-of-heart-disease
          After carb-restriction (though not yet ketotic), my glucose response was much better. So, like many things, I suspect this is highly dependent on many factors and probably tough to overly generalize.
          I still maintain that carb-restriction does not produce the same “variant” of IR that forms the cornerstone of metabolic syndrome, even when this transient issue is present.

      • Pete, are you saying when we go low carb, then eat carbohydrates, our insulin spikes to a higher level than if we were to just be eating a “normal” western diet to begin with? Maybe I’m confusing resistance and sensitivity?

        And, by this article are you saying that we CAN eat too much fat on a LC diet? In other words, x grams of fat (which may be different for everyone) = too many calories no matter how low carb you are, therefore you won’t lose fat? I know you agree that we can eat too much protein, as you’ve said over 150 grams of protein is too much (still waiting on the blog that explains that one 🙂 and can slow down or stall weight loss because that protein is just converted into glucose (or carbs I think). In other words, you believe that if 2 people were on low carb diets (both under 20g per day), but one ate too many grams of protein (200 for the sake of argument), and the other ate too many grams of fat (some arbitrary number that I won’t pretend to know), that neither would be able to lose weight because they either ate too many calories, or too much protein that was then converted to act like a carb by the body?

        Sorry, just trying to wrap my head around this because I’ve always thought Gary wrote and believed you basically can’t eat too many calories as long as you eat LC. You’ll either just not store them as fat, or you’ll be so full you just won’t be able to consume enough to gain fat?

        Looking forward to your response.

        • IR means the cells need more insulin than they would “normally” need to process glucose. When you reduce carbohydrates you experience lower levels of insulin basally (at rest), which has been shown repeatedly — especially in people who are insulin resistant — to reduce IR (which is the same as increasing insulin sensitivity). This is why virtually all Type 2 diabetics can stop using exogenous insulin with months (in some cases weeks) of eliminating carbs.
          What I am saying here is that if you CAN overdo it. Your body wants to be in a state of equilibrium. What that equilibrium is depends on what you eat. I used to weigh 200 pounds eating about 3,200 kcal/day. Today I weight 170 pounds eating about 4,500 kcal/day. Probably less exercise, too. So I have a new equilibrium based on a change in my “inputs.” If I ate 10,000 kcal/day for a month (even if still ketotic), I *do* believe my body would figure out a way to dispose of some of that excess, but not all of it. I’m just interested in doing that experiment as I don’t think I could force that much food down.

        • Debbie

          I’m responding to Peter’s response to Gary. I’ve been eating low-carb for a few months, and have found that my weight still fluctuates. When I ate a lot of nuts – 5-6 ounces – I’d gain. Perhaps I should try extremely low carb, and a tremendous amount of fat – but, I’m a little scared of that – and it seems a bit unappealing. I like my vegetables and salad. I’d love to lose 10 pounds, but that’s not happening, and I can’t see cutting back more on carbs.

  • Eric

    Thanks for another great post Dr. Attia,

    I have always been a “hard gainer” when it comes to adding lean muscle mass. Strength gains are usually consistent becuase of neuromuscular addaptation, but adding muscle is very difficult for me. My question is for an ectomorphic, carb-resistant person (and on a ketotic diet) what is the ideal way to add muscle mass? Do you know of any resources or have anectodal experiences that would help? Should I just learn be happy with my natural morphology? I think you partially addressed this on your reply to Nick M.

    Thanks, Eric

    • Eric, let’s throw this out to the group. I don’t know the answer beyond my hypothesis. Obviously, eating the *right* AA during and after the *right* kinds of workouts matters most.

    • Edmund Brown

      Sounds like we share body types. I am skinny and always have been. When I work out consistently I gain a pound or two, my muscles develop better definition, but that’s about it. Do you need to be ketotic? Perhaps for we scrawny folk need to edge a little into glucose land in order to bulk up… but really my take is – “yes” to your question of being happy with your natural morphology, and assuming you are able to do what you want to do with your body. I mean if there is some goal (sport, athletic event, etc) that weighing an extra stone would help you achieve a higher level that is one thing, but there is so much to life, why sweat it if you’re ten pounds less than you would “like” to be? Probably easier to change your attitude.

    • Michael V


      Purely anecdotal, but here goes. Heavy, below parallel back squats. I’m more of a mesomorph but I ran cross coutnry in high school and 1 year of college. I added about 15 pounds of muscle in my early 30’s, when I ditched the leg extensions and leg curls, and starting doing heavy multi-joint exercises. Back squats was the cornerstone.

  • mike

    I believe I have read every low carb, protein, insulin book and article in the world lately. In the end, aside from eating sugar and white bread all day, it’s still calories in and calories out that matters. Peter, are you telling us your eating 5000 calories a day and not doing enough activity to use those calories and your not gaining weight or fat? Is your entire blog suggesting we can over the course of a week eat more than we use and lose fat?

    Differing diets pushing one macro nutrient ratio over the other and even intermittent fasting all do one thing, the help a person consistently reduce calories.

    Calories in, calories out, with the exception of starvation type long term diets, is the only answer. Always has been, always will be.

    I tried low carb, higher protein, higher fat, aside from water loss, nothing happened. Nope, I was not over my maintenance level either.

    • Mike, I’m not saying that, actually. I happen to eat about 5,000 calories per day BECAUSE of how much I exercise. When I travel, for example, and can’t workout like I normally do, my caloric intake goes down. If you subscribe to Current Dogma, you believe weight gain is determined by the balance of calories consumed. In other words, fat cells will always accumulate fat based solely on the balance of caloric intake. The Alternative Hypothesis says something different — the more important factor from what you eat is how those foods actually impact the “choice” your fat cells make with respect to storing vs. burning fat.

    • Hi Mike,

      “In the end, aside from eating sugar and white bread all day, it’s still calories in and calories out that matters.”

      I think what Peter is saying is that, all though the “calories in/calories out” is true, it’s only a surface observation and that to understand why one person’s body will store fat while another’s won’t requires us to look below the surface.

      For example, you could say that all books are the same. On the surface this is true. They all have covers, pages within the book, etc. However, there are differences in the content contained within the book. There are fictional subjects and non-fictional subjects, romance novels and how-to manuals. Even when two people read the same book they will respond differently to what they read.

      So, back to “calories in/calories out” – this is only a surface fact. What Peter is encouraging us to understand is that under the surface, our bodies in general respond differently to what nutrients constitute the calories. And then even further below the surface, each person responds to those nutrients differently.

      Peter has given us a place to start, but it’s up to each individual person to take the information and experiment to find out what our own bodies need and how it responds.

  • Sabrina Chase

    If you are looking for more topics to write about… 😉 I would like to know more about what kind of tests can tell me more about my body’s metabolism and condition, e.g. the insulin response test, and which you would suggest to get a good baseline on where the problems are or areas of improvement. Thanks for what you’ve written so far!

    • Ok, but probably not for a while. I may end up doing this through another website if I can even created the time to do so.

  • Mira

    Thank you for another excellent post!
    I am family physician and since I’ve started reading Gary Taubes and you I have changed the way I eat and also what I tell my patients to eat. Several of them have already thanked me and told me they feel much better, some of them also started losing weight. I must say that reading all this has completely changed my understanding of nutrition, obesity and my belief in “common wisdom” and “accepted medical practice”. It’s amazing what we have been taught for so long.
    I wanted to ask you about weight loss and a low carb diet. Let’s say someone removed all simple carbs from his diet – no sweets, no white sugar, no white flour, no rice, potatoes, pasta etc. He does eat a little whole grain bread, some fresh fruit and vegetables and the rest is cheese, fish, poultry, cream and milk. No Ketosis. Do you think that there is a need to limit the amounts eaten, or that it’s enough to eat according to appetite or hunger. We have learned for so many years that you cannot rely on hunger or appetite, that we all tend to eat much more than is good for us and that the only way to lose weight is to be extremely careful about how much we eat. If you say it’s usually not necessary to count the calories of the fatty foods going in, then where does the extra fat go? Excreted? Burned? It must be very easy to eat more cream or cheese than you really expend in daily living and excercise.

    Thanks again!

    • Mira, I wish more doctors could be as open-minded as you are and at least question what they have been taught. As a general rule, whether in ketosis or not, appetite is a good guide to returning our weight to our “programmed” state (which does not mean everyone is genetically programmed to have a BMI of 21), IF we consume foods that don’t aggressively promote fat storage. For about a third of folks this seems to result in more calories, the same calories, and less calories, respectively, but I don’t know exactly why?
      So, while it’s tempting to tell someone to eat as much as possible (as longs as they avoid carbs), this isn’t true, as it’s “forcing” the thermodynamic equation towards fat storage. Every case is different, given the complexity of the human body, so I try to avoid suggesting a one-size-fits-all “prescription.”
      I know this is frustrating, because you are looking at an ACTUAL person with all of their own genetic and metabolic nuances.
      It’s not actually clear to me that most people are overeating (beyond hunger) out of habit, for example. Certainly some do, but I think most people aren’t eating THAT many calories. They are eating too many of the calories that promote fat storage, which is a vicious cycle (the foods that promote fat storage tend to make you crave more of the same foods).

      • Mira

        I do think it’s very easy to eat to many calories even while avoiding carbs. I love cheese, cream, nuts etc. I could easily eat much more of these if I wouldn’t stop because I know I shouldn’t. I do think it’s easy to overeat because you like the taste of something. It doesn’t have to be carbs. I wonder what happens to these calories.
        I just wanted to say that even if you cut out most carbs (and all simple carbs), you still have to watch what you eat.
        I do have a BMI of 21, and this is the most I have had all my life. I could always eat whatever I wanted to, but in the last years I had to start watching what I eat, and if I don’t – I gain weight. I’m 52. For the last few months I tried to cut out most of the carbs and eat mostly fat and protein, but I didn’t lose the 2-3 pounds I had hoped to lose. I guess there is no way around it – if you want to lose weight you have to eat less…

      • Anthony

        I would like to share some of my experiences with dealing with carbs like cereals, breads, pasta etc. I found out I simply could not “limit” my above carbs intake. One bowl of cereal deserved another, 1 slice of fresh hot sourdough – forget it, you have to have 3 or 4 while its fresh. Point being I could not be trusted with these types of carbs, so the only way to deal with them was to elimiate them. I also found that off the carbs I no longer experienced the sudden drops in energy and raging hunger. I also found that I just wouldn’t overdo foods like cheese or cream. I never felt the urge or need to eat them like I would carbs. Since ditching carbs about 3 months back, I have not overeaten in the manner I would have if there was bread, cereal, rice or pasta involved. The desire, the urge or whatever it is, just isn’t there. For the record, I was not obese, and would only consider myself 10-15kg over a very lean weight. I don’t count calories or weigh my food, and the weight (body fat) has steadily come off. While on carbs I would at times be driven to anxiety over trying NOT to go back for more of the same. I can’t imagine how overweight & obese people cope like this.

        • Anthony, I share your experience with respect to carbs. It’s MUCH easier for me to limit them absolutely (as I do now) versus when I was just reducing them heavily and still intermittently eating them. But everyone is different.

    • Debbie

      I agree with you, Mira. I’m 56 and could happily eat cheese and nuts all day – and if I eat “too much” weight comes on. I really would love to hear from more women, especially older women, on this issue. I love that Peter Attia is telling us he doesn’t KNOW, that we’re all different, that the science isn’t there yet. How refreshing to be told the truth! But, the more experiential information we all share, the more we can learn.

  • Peter, thanks for the excellent article on CICO (calories in, calories out). However, you have one underlying assumption wrong, which is that the FIRST Law of Thermodynamics applies to humans. It doesn’t. The First Law applies to closed systems like car engines, which is definitely not us.

    It is the Second Law of Thermodynamics which fits your argument perfectly. For an explanation of this and a thorough debunking of CICO, see:

    There you will also read why your answer to Lal (#12) about what would happen if you ate enormous excess LOW CARB/HIGH FAT calories is incorrect. You wrote: “ASSUMING they can physically eat that amount of food… they almost certainly WILL gain weight.”

    Turns out, not so. You can read the actual data on the thread, but to summarize: “To prove how ridiculous CICO really is, two young, healthy male MagicBus members agree to eat excess thousands of high fat/low carb calories every day for a month, with no exercise. Their measured RMR was between 2300-2500 calories, so they agreed to try and eat double that amount, about 5000 calories a day. Eating that much is harder than it sounds; one of them (Jeff) resorted to drinking quarts of heavy cream daily to get there. Results after a month? One neither gained nor lost an ounce; the other lost weight.”

    Finally, in response to a comment you wrote: “In general …exercise per se does NOT seem to lend itself to sustained weight loss… However, people who exercise are often more careful about what they eat, and this confounding factor can create a bit of confusion around the process.”

    I believe the confusion actually stems from the LC community not understanding that how exercise affects individuals is no different than how sugar affects individuals with normal or insulin resistant metabolisms. It has nothing to do with being ‘more careful about what you eat” at all, but rather how your body processes what you eat, and how it processes *your* exercise.

    Healthy young men can exercise a lot and vigorously and as a result have their insulin sensitivity increase. Women with the insulin resistant variant of PCOS however, who are very sensitive to the insulin-suppressing effects of cortisol, only store more fat when they vigorously exercise. Once the PCOS is cured and insulin sensitivity is restored, they can exercise however they like to excellent effect. So I would say that exercise never *causes* weight loss (no matter how “carefully” you eat) but rather, in a healthy metabolism, it can help to maintain normal weight and fat levels.


    • Thanks for your great comments. While the First Law certainly DOES apply to car engines, it’s actually universally true for any closed system, including humans, assuming we define the closed system correctly. Same is true for the Second Law, as you point out.
      I’m not sure I agree, though, that EVERYONE who forces down, say, 3 times their energy requirement will NOT gain wait if they avoid carbs. It’s been true for me and about a third of people I’ve worked with (which, admittedly, is a modest number of people in absolute amounts), but I have seen more examples where this experiment results in weight gain. My point, I guess, is that this is complicated for reasons that extend past what I understand. I have observations, but I don’t yet have a unifying theory as to why some folks can do what I do and others cannot, with respect to eating seemingly unlimited fat calories.
      I think your point on exercise is interesting, but but I wonder if it’s even more nuanced than men v. women? I suspect type of exercise, genetic (beyond gender) differences, peri-exercise nutrition, and several other factors play a role. Great discussions, all around.

      • Hi, Peter. I’ve been busy with my own blog but really enjoy reading yours, and so I returned to read your reply to my comment. I fear I wasn’t entirely clear so let me try again:

        You wrote: “I’m not sure I agree that EVERYONE who forces down 3 times their energy requirement will NOT gain wait if they avoid carbs.”

        First, carbs aren’t the only issue. If you have the insulin resistant form of PCOS, then excess protein (even without ‘excess’ calories) will cause weight gain.

        Second, this is where most folks who claim that calories don’t matter (if composed of the correct nutrients for YOUR metabolism) fall into the double standard hole. Either a calorie is a calorie is a calorie — and the number of them you ingest matters. Or not. Because if not on the way up, it is not on the way down, either, no matter how many calories you eat if they are the right type. For you that is.

        And we have, in fact, proven this now many times over in the Protocol section of my blog. Once broken metabolisms are healed, calories do not matter if we eat the right kind of calories. I’ll talk about me in a moment, but want to say now that we have dozens of women who report daily (weight, meter readings, measurements) and who have done so for a year. The data is there for anyone to see. These women are ingesting, daily and over many, many months — an enormous amount of calories (a minimum of 1700 calories in FAT alone, not counting carbs and protein!) that is far above their BMR. Not only do they not regain any of the pounds or inches they lost, they continue to lose even more as they eat more over time.

        As for me, I am 5’4″. Five years ago I weighed 240 pounds, my measured body fat was 53% (that’s not a typo), my (then) undiagnosed blood pressure was 195/110, my leptin level was 35 and I wore a tight size 24 dress with a 51″ waist.
        At that time I was faithfully following my doctor’s advice by eating an extremely low calorie (1100 per day) low fat (10%) diet. And I got fatter and fatter. That’s right, on only 1100 low fat calories a day I was gaining weight. You would say “you were eating the wrong kind of calories” and of course you would be right.

        But the opposite must then also be true: if you do eat the right kind of calories for YOU, the number of them is immaterial because the body will simply burn off any excess it does not require. I don’t believe you can have it both ways: calories don’t count on the way up, but somehow do on the way down or when you’ve reached goal.

        Back to me. I created my Protocol and went on it. For the last three years I have weighed 145 pounds, body fat is 25%, my blood pressure without medication is 110/65, my leptin level is 8.5 and I wear a size 8/10. I am 64 years old, do not do strenuous ‘formal’ exercise of any kind, and I eat about 3500 calories a day, mostly fat, which is far in excess of my basal needs. I don’t gain any weight from year to year and I wear the same clothes which neither get tight nor loose. I’ve gone down 1.5″ around my neck, and lost 20″ from around my waist — all while eating enormous amounts of calories — the right calories for ME — every single day.

        My son, who is 6′ and who eats as I do, has a desk job and eats at least 4-5k calories a day, every day, certainly above his ‘needs’. He weighs 149 and his body fat is 6%. We sometimes laugh when we dine out and have a huge cheese plate for dessert after eating a huge meal, smearing butter on our brie and enjoying every bite. According to CICO, we say, we should be too fat to fit through the door of the restaurant! 🙂

        Needless to say our lipid profiles are great; his because he’s young, and mine, with TG’s of 42 and HDL of 97, because I;m eating the right type of calories for me and I know the number of them does not matter.

        You also wrote: “I think your point on exercise is interesting, but but I wonder if it’s even more nuanced than men v. women? ”

        I wasn’t actually talking about the difference in exercise between men v. women when it comes to PCOS, but that for men AND women who are insulin resistant, strenuous exercise that raises cortisol and depresses insulin raises blood sugars, and that means weight gain. I love to do heavy weight lifting but cannot, because within a few weeks of starting, I gain fat around the waist as my blood sugars increase. Hateful, but true. What I was saying about men v. women was simply that I believe the cause of, and treatment of obesity in them is very likely not the same. I believe research will show this to be true some day, and I hope that day is soon.

        Thank you for your excellent blog, and thank you for listening (even to ideas to which you might not agree). I do hope however, that you will come to sugarfreegoodies.wordpress.com and look at the data we’ve accumulated.


  • Garth

    I suspect you’ve addressed this somewhere, but I can’t find it.

    What do you think of the ability of certain foods – eggs, beef, etc. – to cause significant insulin secretion? Do you view this as less problematic than carb driven insulin secretion? Is there a good way to measure insulin levels distinct from blood sugar, and is there any point?

    • Protein certainly stimulates insulin secretion, though to a lesser degree than carbs. There is no reliable way to predict insulin levels (or ketones levels, for that matter) from glucose levels. I’ve tried several regression models from my own personal data and find them wholly unsatisfying.

  • DianaEdd

    Yes, insulin plays a major role in fat accumulation. I believe this and like your discussion so far. However, I just keep wondering… It seems that after eating a particularly fatty meal I am much warmer and also my digestion seems to change as well, so it would seem that other factors are playing a role here, unless one thinks all this mediated thru insulin.

    • Anu

      Just speculating here, but it’s quite possible that the lack of insulin is causing your body to partition more of the energy you’re consuming in the form of food into heat production, leading you to feel warmer. If insulin’s role is to increase the proportion of energy consumed that is stored as fat, that would make sense. Anyway, it’s an open question and I’m sure Peter will have more ideas, was just thinking out loud 🙂 Anecdotally, I too find that I am warmer on a ketogenic regime than otherwise (which is just lovely in the cold Northeast).

      • My guess would be increased thermogenesis. I.e., you body is “getting rid” of excess energy as heat production.

        • Paul

          While thermogenesis might be part of it, I would guess the first order effect is in the energy content of what we leave behind in the toilet (as well as what we exhale when in ketosis — ketones have significant energy content, similar to alcohols). This is part of the first law of thermodynamics as Peter mentions, but seems to be routinely ignored. It’s astounding to me that studies (apparently) have not been done to quantify this important dependent variable.

          • Great points, Paul. This is why we need to do extremely rigorous studies in metabolic wards with metabolic chambers. There are folks out there, like Kevin Hall at NIH, that are leading the way in this field.

  • Birgit

    Wow! Awesome blog and awesome, thoughtful responses! This is soooo much fun. 🙂
    I can’t wait for this info to hit critical mass. I know it will soon.
    I keep learning more about the influence of all hormones as time goes by but I have no doubt that insulin makes the biggest difference.

  • KevinF

    Tapping a few of the concepts mentioned above (exercise, dogma, basal expenditure), one bit of dogma I’ve often heard and read is that exercise — of one form or another depending on who’s proselytizing — ramps up your basal metabolism for some period of time after working out. Hence another advantage to exercising. Do you know if that’s true or is that an old wives’ tale?

    • Kevin, the so-called “after burn” effect is not a wives tale (assuming you do the “right” kind of exercise). The question is (or should be), how CLINICALLY relevant is it? In other words, if I get an “after burn” of increased expenditure of 125 calories per week out, but my appetite — either that day or more often the next — increased by that amount plus the amount of calories I expended during the workout (if not more), does it help?
      There is obviously more to this, but clinical evidence has shown us that on average this effect seems to not make a difference in weight.

  • Neil

    I’ve often wondered about a possible exception to the alternative hypothesis in terms of exercise and fat loss. Let’s say I eat 100g of carbohydrates a day, for the sake of argument. Then I decide I want to start exercising everyday, but only satisfy my hunger with additional protein and fat to match my expenditure, while keeping the carbohydrate amount the same. It seems like in this scenario exercise would/might lead to modest fat loss, as the exercise would mitigate the effects of the 100g of carbohydrates.

    • Certainly possible. In fact, Neil, you’ll want to tune in for next week’s post where I talk (peripherally) about an example very close to the one you’ve described – not for weight loss per se, but for maintaining ketosis.

  • Mike

    Thanks for the great blog post. This was a big question for which I’ve been looking for a well-formed answer. As a chemical engineer with plenty of biology/biochemistry coursework, I think you do a great job explaining the science. Sometimes things get dumbed down for mass-consumption to the point where alarms start ringing for my inner skeptic. You don’t do this. This is just a very well-written and intuitive explanation for low-carb weight-loss/gain mechanisms as distinguised from the conventional wisdom. Keep up the great work.

    • Thanks very much, Mike. As you, it’s an important balance. My “desire” is usually to err on the side of overly complex, but I want to make the information is helpful, too.

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  • tivoboy

    I really wonder if there is some formula that can be used to rebut or improve the laws of thermodynamics. As a case in point, myself, counting calories and measuring daily metabolic rate/burn and exercise output, I can tell you that the law can certainly be broken. As a more recent scientific test on myself, 90 days, calorie restriction, 1200 cals a day consumption of 90%+ proteins (1400 average with a measured weekly carb increase), and a BMR of 2500 (not including additional outputs) the math works out to a caloric deficit of OVER 100K over the 90 days not including any weekly exercise component. This should have been a long enough example of caloric restriction testing. And yet, while the math says the weight loss of any kind (it was literally ALL fat in this case from hydrostatic BF testing!!) should have been close to 30 LB, the actual total FAT loss (and overall weight loss) was 12LB. That would require a measurement error of over 100% which is simply not possible. can the body photosynthesize?

    How can the primary law be so wrong?

    • Cool experiment! Couple of things: 1) How did you calculate BMR and how often? It’s not static, so assuming it was calculated correctly in the first place, it was RAPIDLY declining with caloric restriction; 2) Hydrostatic testing is not particularly accurate, especially compared to DEXA, depending on body type. I once did a hydrostatic and DEXA on the same day and the difference was 4% (13% vs. 9%) — that’s a huge difference.

      • tivoboy

        I did BMR using the o2/co2 measurement devices, once a month. estimated BMR (so resting) remained within about 10%, going from 2490 to 2300 at the end, so I wouldn’t say it is crashing. BF testing was all Hydrostatic, don’t have a DEXA lab nearby and it’s quite a bit more $$. Regardless, prior to DEXA, Hydrostatic was the gold standard with error rates of 1-3%, that isn’t 1-3% BF measurement error but 1-3% as normal. It SHOULD be relatively good for measurement especially with same process (same day of week, same diet, same hhmm, output, no eating for eight hours prior, etc.) I’d like the think that the measured move from 30% BF to 24.5% is pretty close to the MOVE, if not the most accurate nominal values?

        But what about the thermodynamics of it all? Why can’t it be better calculated and analyzed?

        • It can be much better calculated, but you’d need to lock yourself in a metabolic ward, under a hood, with precise calorimetry 24/7.

    • KevinF

      The body is not a machine that can be so finely calibrated and expected to operate so consistently. I think Peter’s diagram above is very instructive, showing “Energy In vs Energy Out” variables.

      The laws of Thermodynamics rest assured are not wrong or being violated. What’s happening is that your energy-out variables are simply different than you expect them to be, and probabably changing radically during the course of your experiment. Perhaps shouldn’t be a surprise that your body would react somehow to a semi-starvation nearly all-protein diet by becoming more efficient in conserving energy.

      The body’s not a calculator, it’s a steamy bag of wet chemicals. This is complex biochemistry, not simple arithmetic.

  • Mark

    What happens to unused ingested fats? Is it unhealthy to eat too much fat?

    • Not sure I understand question. What do you mean by unused? If fat is not expended (by the 4 ways we expend ingested food), it is stored.

      • Mark

        So fat turns into fat if not used?

        • Yes, but be VERY careful you understand what is meant by “used.”

        • Mark

          For instance, you have turned me on to the heavy whipping cream latte and yesterday I had two of those. That is a lot of calories from fat. So, if ingested fat is not used as energy for the body it will be stored as fat and does not magically get eliminated from the body. The good thing about fat is that it does not trigger your body to create insulin, so it must become fat in your body by another mechanism?

          • Or it sufficiently satiates you and/or your body expends of it another way (remember all of the ways your body expends energy).

  • Alex Carvalho

    Thanks for another great post. I’ve been in ketosis for a month now, with ketones levels on my blood around 1 every time I check. Similarly to what some of the other commenters revealed, I too feel a bit disappointed about having lost only 7 lbs of weight so far, most of it during the first 10 days (my waist is also slimmer by 2 inches). I read about these spectacular weight loss rates that people seem to experience effortlessly, and maybe I just set my expectations too high. I keep wondering whether I’m doing everything right, though. My question to you is: what items should one check to “troubleshoot” a ketogenic diet and make sure everything is being done properly?

    • Too much for even a post, let alone a question. Best reference out there is the book I recommend by Phinney and Volek.

      • Alex Carvalho

        Thanks again. Following your tip I read an excerpt of the book and already ordered a copy. Looks promising.

    • Hi Alex – Sounds like we began ketosis about the same time.

      I have been restricting carbs since last summer – no sugar, no HFCS, no grains, just low glycemic veggies, but I was eating a lot of veggies and not in ketosis. 3 1/2 weeks ago I lowered my carbs to under 30 grams. I record my daily weights and daily body fat (by hand held Omron) on a spreadsheet, and calculate 7 day rolling averages, which smooths out the daily ups and downs. I keep a food log on fitbit, and have kept my protein in the 100-125 gram range. Based on the 7 day rolling averages, I am losing 1.6 lb per week total weight and 1.3 lb per week fat. I track my total calories eaten vs my calories burned (from fitbit) and watch my daily calorie surplus or deficit. I have found a strong correlation between the calorie deficit and my rate of weight loss. I compare my actual weight loss vs. calculated (from the calorie deficit) and find the actual weight loss exceeds the predicted, so maybe my basal metabolism is running a little higher than the estimate.

      We all respond differently. You might experiment with different amounts of calorie deficits, see how it affects you.

      • That’s the spirit, John. Well said. We all respond different. Best to do good (i.e., controlled and sufficiently long) self-experiments.

      • Alex Carvalho

        Thanks, John. I have been trying to keep things as simple as possible. Eat when I’m hungry. Measure my weight and waist line and check the ketones level on my blood once a week. Maybe I’m keeping things simpler than possible. I haven’t been keeping a food log. Perhaps it’s time to begin one.

    • Alex Carvalho

      Dr. Attia, thanks for pointing me to Phinney and Volek’s book. It’s a great read indeed. I’ve read it voraciously, troubleshooted my diet and I’m now shedding 2.4 lbs off my body per week. I followed John’s advice above, which is also stated in the book, and started to log everything I ate on fitday.com. As it happens, by just estimating what I’ve been ingesting (as I was doing before) I ended up eating too many carbs. Bringing the carbs back down to 20g per day did the trick. Interestingly enough, calories went down with the carbs (I know because fitday counts them automatically), as my appetite was more in control. I’m now as happy with my diet and energized as it gets!

  • Peter, love the blog. I’ve been eating very low carb for about 8 weeks, and ketogenic for roughly 3 weeks. I have a general question about insulin: If a eat a meal high in fats with (for argument’s sake) 0 carbs of any kind, should my insulin remain completely unchanged? I remember the concept (Tim Ferriss – 4 hour body) that if you simply eat a normal meal slower, you’ll lower your insulin response (the sugar hits the system slower). Is this irrelevant in a ketogenic diet? Can I eat as fast as I choose? When I wolf down a meal, i used to feel that plummet in energy, now I feel an incredible rush of energy. Am I getting a blood sugar spike from the fats without any insulin (to protect me)? Could this be dangerous?

    • Not really an issue if you’re fully in ketosis as, by definition, insulin levels are so low (if they were not, you’d quickly fall out of ketosis). Fat does not stimulate insulin. When in ketosis, the greatest driver of insulin levels is actually protein intake.

  • Phil

    Peter: great series of articles and looking forward to further clarity of thought from you. 

    I feel after nearly two years with a generally low carb approach to diet my metabolic system has attained a high degree of flexibility. Such that I have achieved a good body comp which I can maintain comfortably by cycling between high carb days and near ketotic days. In some of my earlier efforts I struggled to maintain body comp though, believing the mantra just eat real food, and carbs don’t matter. I have shown to myself that carbs do matter, in the context that my metabolic systems were not running optimally to the extent that I could maintain a slight negative energy balance and control appetite so as to achieve body comp goals.

    I would be interested in your view on the debate about the role of carbs that has resurfaced and is nicely laid out at Richard Nikoley’s blog http://freetheanimal.com/2012/02/synthesis-low-carb-and-food-rewardpalatability-and-why-calories-count.html. The essence being that a number of LC and VLC are finding health benefits in introducing carbs back into their diet. 

    My interest in your approach, given the accounts of you and others, is toward the claimed mental acuity brought on with being in nutritional ketosis. 

    • Phil, thanks for passing along. My biggest hesitation when deciding to write a blog was that people would assume everything is binary — black or white. While there are SOME thing in biology that behave this way (e.g., action potentials), many things are actually shades of grey. The way our bodies maintain thermodynamic order is perhaps one of the greatest example of this phenomenon. So the “calories” discussion is particularly vexing, as there is a SPECTRUM. I do not doubt the veracity of Mr. Nikoley, but I equally do not doubt the veracity of countless others (myself included) who actually INCREASE overall caloric intake or maintain caloric intake when removing carbs for months to years, and still reduce fat burden. How is this possible? Great question. How is possible that 100 people can smoke a pack of cigarettes every single day for 30 years only 17 will die of small cell lung cancer (a cancer almost exclusively linked to tobacco use)? Another great question! We’ve got to recognize that an infinite number of genetic polymorphisms probably account for the different susceptibilities and predispositions we have.
      I would like to take the “debate” to a state of hypothesis testing. Not mickey mouse self-experiments like I’ve been doing my whole life, but REAL metabolic controlled experiments where we test one variable at a time and start to parse out the nuances.

      • Michele

        You may label your experiments as “mickey mouse” in comparison with the real science you would like to achieve with NuSi, but please keep in mind that those experiments, no matter how “mickey mouse” they may seem, are helping all of the people commenting here – which is a lot!

      • Phil

        Thanks Peter, yes agreed re the shades of grey. And on reflection my points should be refocused toward what health/performance/life goals are wanting to be achieved. With LC or VLC, being but a pathway or mechanism toward an outcome, in this case combined with managed protein consumption, nutritional ketosis.

        I agree with you regarding the mickey mouse self-experiments in the context that a lot of this “science” is relatively immature, given just how much we dont know. I think the upside is that people do have to self experiment, and it will be interesting as to what rational information you will be able to produce to guide future generations in how to improve their health. Or will nature and individual variability continue to confound us. Interesting times!

      • Elton Wilson

        The real issue with Richard’s post and others is that they no longer think insulin is a major contributor to weight gain and ill health. I don’t always eat VLC, but I also don’t agree with the Food Reward theory.

        Peter: have you looked into this theory as valid? I know taubes has a great post countering this, just wondering what your opinion is?

        Another question Peter, since you are so great at responding. If someone stalls on a low carb diet, would you recommend lowering protein before increasing carbs?

        I have always recommended this, but it seems that people coming from the Atkins approach don’t think too much protein can cause any issues. Just a small example: both my wife and my brother had issues on a low carb diet until they controlled their protein intake. My brother, for example, was eating a ton of beef jerky, which is almost all protein and no fat. He was getting migraines and started blaming it on the LC diet. I recommended not eating so much protein and switch to higher fat snacks like Mac Nuts and Almonds. And my wife started cutting out the whites on just one of her two eggs and that made a big difference.

        I know that everyone is different, but it seems that the “paleo” community now recommends adding carbs instead of lowering your protein.

        Interested in your thoughts.

        • Elton, I have yet to be convinced that the food reward system is the FIRST ORDER term driving obesity. I don’t doubt, however, that it could play some role for some people. I just do not believe it is the primary driver to what is going on. Part of the problem (and we are ALL guilty of this – me included), is we tend to focus on the hypotheses we find most convincing, sometimes at the exclusion of giving equal consideration to others. It’s an inherent bias problem is science. The key is being open minded enough to at least ask questions.

          My response to the plateau problem is very individual. It varies by so many factors, I can’t really say definitively what the answer is. I do tend to experiment with protein reduction first, if intake is north of about 120-150 gm/day.

  • Eating in Orlando

    Great article, and thanks for responding to comments so diligently.

    On observation I have had, is that when we argue against the simplistic conventional wisdom “calories in/calories out” model, body temperature should be taken into account. We are not all at exactly 98.6 degrees all the time. Our bodies are not perfect Newtonian machines that obey a strict energy in / energy out balance. To say so is to ignore that our metabolism can and does adjust to different circumstances. We burn different fuels, at different rates, depending on a multitude of causes.

    Just an observation.

    • Certainly. Thermogenesis is part of the equation, as it drives a large part of our metabolic expenditure to maintain body temperature in such a narrow band.

  • Maryann

    Dear Peter,

    Thank you for all you do and for being so inspirational! There is so much great instruction in these posts; I wish I could find things easier; for instance, I read somewhere that I should increase salt and fat. I wanted to know how much to be consuming, but I have been pouring over all of the comments and articles, and I can’t find where I read it.

    I have just begun this way of eating, and I have a dilemna. As a practicing Catholic, I am stuck with no ideas for the many meatless days during Lent. Ordinarily, my husband and I would have a peanut butter and jelly or cheese sandwich for lunch and ravioli or pasta for dinner. I can’t cook/wouldn’t know what to buy/don’t like fish. I can’t think of anything but scrambled eggs or omelettes for protein. (I don’t think we are supposed to be eating a salad without a protein, is that correct?)(Doctor nixed canned tuna I used to give my husband because his mercury is high). I can’t find a low-carb protein bar that doesn’t knock me out of ketosis (according to ketosticks). Would you have any ideas to suggest for meatless days and do you know of a bar that is truly low-carb? Thank you so much 🙂 maryann

    • I think you would really benefit from reading the book by Volek and Phinney on my “books & tools” section.

      • Maryann

        Thank you Doctor, I will get this book. I have read WWGF and recently ordered GCBC. I appreciate all of your help, maryann

  • Viktoria

    Have you thought of perhaps not only providing this type of information to the public (thank you for that!!) but also perhaps developing material for the medical crowd? Perhaps something aimed at the family practitioner? Perhaps even the pediatric practitioner. Maybe give a talk at a conference or two…

    I see that you visit Tim Ferriss’ site, and it occurred to me this might be a relatively untapped specialized market.

    Even if they didn’t buy in to the insulin-hypothesis, if they realized how little real data backed up the low-fat recommendations, I’d like to think that many would be shocked.

  • Hey Peter, I was reading back through comment threads and came across e one where the guy was asking if maybe “heart healthy whole grains” would actually be worse as they keep you out of ketosis for longer and it got me to thinking and questioning things (aside from, “do you actually need to consume carbs immediately post workout to prevent catabolism”, which I think you answered admirably. Anyway, I know that everyone says that protein causes “some” insulin secretion, but do we know how much? I don’t know the chemistry myself but I’m sure that you, or one of your readers, you can do the math to get a ratio, i.e. 4.2 grams of proteins generates the same amount of insulin secretion as the consumption of 1 gram of carbs. The main reason I ask is because I was at the grocery store and they had a special on scallops so I probably just ate about a half of them knowing them to be carb free, but then I look at the label and find that they contain 20 grams of protein, naturally no carbs, but only a gram of fat, so, um, yeah, hopefully the utter I sautéed them in added a sufficient amount of fat 🙂

    • Chuck, insulin secretion varies a lot by protein and, of course, insulin sensitivity, just as it does with carbs (i.e., all carbs do cause the same insulin response). Don’t worry about an extra 20 gm of protein through some yummy scallops.

      • Haha, it was more like 75 grams…I had 3 3/4 “servings”, but, ok, if you say don’t worry, I won’t. I was just wondering if there was some kind of formula to be following, but I guess that, until I manage to get myself or do for myself a more individuated prescription, I’ll stick with “1-2gm./kilo of body mass a day”, but I’m definitely going to read up and see if I can’t find some measure to fine tune that.
        Thanks again.

  • Ilkka

    Hi, great blog. You inspired me to go all the way with carb restriction after a year of no sugar 🙂

    I have this one thing I’m confused about though. I see a lot of people making the assumption that “if I’m in ketosis, my insulin levels must be low”. Is it really always so? It’s my understanding that being in ketosis just means that your glucose levels are low, and body must break down fat to ketones to compensate. Where does the insulin come to the picture?

    Yes, low amounts of glucose usually cause insulin levels to drop, but is low insulin a requirement for entering ketosis?

    • This is a a very good question. Insulin suppresses ketone production, which is WHY you need to have low glucose (and modest protein, which also stimulates insulin) to generate and sustain ketones. So, if someone is in ketosis, it implies (though we don’t often measure it) that their circulating insulin levels are low.

  • Robert I


    I realise that mouse studies don’t add much to the topic, Peter, but have you ever wondered about a possible link between BPA and insulin resistance?

    Robert I

    • If a link exists, which is certainly possible, it’s probably a 10th order effect. Why? Because there are many cultures that have never seen BPA that are still full of obesity and IR. I’m dismissive, as you know, of extrapolating anything from mouse to human for the reasons I’ve previously discussed. Like I said, this does not say BPA is “good” or that it doesn’t contribute to the problem, but it’s an edge effect, at best, I suspect.

  • Samantha

    I’ve read a lot of these comments and they are all very interesting, especially wrt home experiments. I am wayyy too lazy to do my own home experiment, so I am thankful to those who do and report what they have found, even though it is only to a first order approximation. As of late I have been reading about leptin and its relationship to insulin resistance. I am so perplexed! I am a PhD in geochemistry/oceanography, I study all kinds of chemistry, but I am most fascinated and frustrated by my work with the marine nitrogen and carbon cycles. You have to tell the general public that x amount goes into the atmosphere from y sources and they end up in the oceans due to z processes .. but then you have this offset of like a million billion when you do the math, so everyone assumes you are wrong–but in effect you just skipped all of the biological complexities that still never fully mathematically explain the numbers modeled vs. measured. And even a small difference could be due to some genetic adaptation that changes a cycling source to a sinking source. So I am now reading about metabolic processes and the more I read, the less I feel I understand, and the more reading I need to do. And now, after finally completing my phd, I am seriously considering taking the MCAT and going to med school just to learn this stuff better, isn’t that nuts?!

    I like complicated systems. I love chemistry. I think that is why I like low carb–I feel like it is a big chemistry experiment using my body as the laboratory. That is why I didn’t have a brownie yesterday when I was at my friend’s house and they were repeatedly shoved into my face.

    • Samantha, you do NOT NOT NOT NOT need to go to medical school to learn this stuff!!!! Only go to medical school if you want to be a doctor. If anything, medical school will do wonders to help you UN-LEARN this stuff.

  • Debbie

    I have a question about nuts and omega-3s & 6s, and wasn’t sure where to ask it, so that you’ll include it when you get to that topic. I understand most nuts have a very high 6 – 3 ratio, which we know isn’t good, with the exception of macadamia nuts. I take fish oil – Krill and Cod Liver Oil – but of course I’m wondering which nuts are “best” to eat daily, how many, etc. Would eating 2 – 3 ounces of almonds and walnuts a day skew one’s omega 3 and 6 ratios in an unhealthy direction? Also, what about the acid alkaline aspects of these nuts?

    Thanks so much.

    • Unless you are eating large quantities, this is less of a concern than the actual carbohydrate content of the nuts. The real place to look out for too much n-6 is in plant oils.

  • Dave Nelsen

    Peter, really enjoy the blog. After doing LC off and on for the last few years, I know that is the way I need to eat to lose weight and not be tired all the time. My biggest thing to overcome is regressing and eating carbs as I’ve eaten them for a long time and the LC diet can be somewhat limiting at times. For a long time I felt LC would help lose weight but due to all the naysayers I felt it was unhealthy at some level. After reading Gary’s books I’ve changed that opinion. My wife and I have recently restarted going LC again and I’m convinced to keep on it long term now. One thing I’ve learned on your blog is that you can have too much protein on LC and I’ve been working on changing that going forward. I have one question with regards to fiber. For proper bowel movements I have to take Metamucil every night after dinner. I take the sugar free type, but am concerned that the sweetness of the Metamucil might be kicking me out of Ketosis. Do you have any insight into this? Thanks, Dave

    • Possible. What if you switch over to mineral oil and bouillon? Does much more for bowel irregularity without the harmful effects of supplemental fiber (lots of evidence this is actually harmful to the colon – I’ll write about this in a while).

  • Kim Carnes

    I’m peri menopausal at age 48. I’ve been on every eating plan. Nothing seems to work. I just found Gary Taubes articles and have decided to give low carb a try. I’m 5’1″ at now 155 lbs. I notice my weight is in middle of my body. I never had a problem loosing in past. I would love to go below 150lbs. Will eating for fat work for me. Peri menopause and hormone issues seem to be the problem. I’m desperate to get 25lbs off and feel normal not tired and sluggish.

  • Ted

    Great blog. One question keeps nagging at me. You read all kinds of material and met with Gary Taubes, but you still didn’t follow the guidelines for the new Atkins diet as far as bonking the first weeks?

    • Ted, I actually have not read the “new” Atkins.

  • Andrew Crews


    I saw one of the of your comments talking about thyroid issues and low carb dieting, I thought maybe i could help. It would seem there is a considerable amount of people who develop thyroid issues after low carb dieting. I personally had some anomalous thyroid level readings after the first year of low-carb dieting. After coming upon some information in “The Art and science of Low Carbohydrate Living” by Jeff S. Volek, PhD, RD. I think I came across a good hypothesis.


    essentially , The amount of carbohydrate restriction increases the need for salts. High carbohydrate diets make the kidneys retain salt, whereas a low carbohydrate intake increases sodium excretion by the kidney. My hypothesis is, with the mainstream media’s horribly generalized mantra of “eat less salt, or you’ll get high blood pressure. Many people decrease their carbohydrate but also end up drastically reducing their intake of salt. much of the low-carb diet information I see, comes attached with many warnings of about the dangers of processed food. Many people including my former self associated salt with processed food. The key to all of this is that iodized-salt intake is the thyroids main source of iodine in most diets, especially those lacking SEAfood (read, not “fish”., tilapia won’t cut it). Iodine is essential for the production of thyroid hormone which is in turn important to the regulation of the endocrine system. So I think a large source of these thyroid issues, are from the body experiencing a large increase in the amount of salt leaving the body and a large decrease in intake of salt and with it iodine balance.

    • Andrew, yes, I’m very familiar with the salt connection. One of the toughest lessons I learned (personally) on my journey into ketosis was the absolute importance of salt addition. I consume about 6 gm per day. The salt (NaCl) to iodine link makes a lot of sense. I think I still need to do a bit of work to figure out if there is anything else going on, but this is certainly a major issue I don’t thing everyone cutting carbs is aware of. Thanks for pointing out.

  • Bobby

    Peter: First, let me say that I love your blog. You are a smart fellow who writes well and your self experimentation has given you a well reasoned position on diet. I gather you are saying that your diet will work for some folks, but not everyone. How long does a person need to try a high fat diet to know if it is working for them, and how do they judge that?
    Thanks for any insight you can provide. Very sincerely, Bobby

    • Bobby, thanks for appreciating the art and science of this. My thesis is this: there is virtually no one who will NOT benefit from carbohydrate reduction. The extent to which you restrict is a function of 1) your genes, and 2) your goals.
      In my experience, it takes about 12 weeks to really adapt to a significant dietary change, ASSUMING you’re doing it correctly.

  • Dave

    So do you have any opinion about whether leptin plays a significant role in obesity or is it primarily just insulin?

    • Big questions, Dave, and beyond the scope of a quick response. Leptin certainly plays a role, but the overlap with insulin is significant. I will write about this in time.

  • Hi Gary, I’m a 53 year young Menopausal and facing the Cape Argus cycle, 106 I’m cycle race. Purely do these races for the enjoyment and goal for my gym work. I’ve followed Low cab diet for 7 wks now, lost 7 kg that I had battled to lose over the past 18months so feeling great @ present! Only concern is getting my mind around no carbo loading before race day and then what do I take on the bike?for energy during the ride? Sem to manage 2 hrs training on water but the ride could take me 5 hrs, help will water be enough? Would hate to bale out of the race because of lack of energy…I don’t need to break any records but want o feel good at the end of the race.any suggestions

    • Julie, I assume you’re asking me (Peter, not Gary)? Stay tuned for tonight’s post. It will address this exact question.

  • CS

    Thank you for this discussion.

    My ongoing experience is this: since much of my eating has always been compulsive, rather than hunger-driven (I am always amazed and saddened that what has been learned in Overeaters Anonymous never makes it into general discussions of diet and weight), allowing unrestricted calories even with very very low carbs doesn’t work for me.

    While it is true that eliminating carbs–especially sugar–reduces my cravings, I want to make up the carb deficit with more fat and protein: quite simply, I want to eat as much as I always did, just different stuff. I eat compulsively. As a result, in the past, on Atkins, I have lost no weight. I always found that confusing and disheartening.

    I am grateful that you, unlike some others in the field, acknowledge that unlimited non-carb eating might be OK for some but not for all. It seems in part to come down to what drives us to eat. If it is simply cellular hunger, then people like you and Gary Taubes, whose work I admire greatly, can rely on your appetites to be your guides. But for compulsive over-eaters like me, conscious control of amount (i.e. calories) is still necessary.

    That being said, no, in my experience a calorie is not a calorie, and sugar is not cabbage or hamburger. Thus this low carbohydrate approach, combined with a self-conscious moderation (I do have to count calories) has been what is working for me. I thank you for your support in this endeavor. For me, eating low carb is backed by compelling evidence, but the “eat lo carb and you can eat as much as you want” is a non-starter: my wants are endless. I know I am alone in this regard.

    • Glad you’re finding this helpful. Thanks for sharing your experience.

  • Razwell

    Anthony Colpo has been completely DISCREDITED by this article.

    Dr. Attia, Dr. Linda Bacon. Dr.Douglas Coleman – all of their SCIENCE articles discredit Colpo abd Richard Nikoley’s recent nonsense.
    Calorie labels are off by as much as 80 % !

  • Michael

    hi, have you seen this? they put a couple of gorillas on a low carb/low glycemic diet and they lost weight even though they ate more calories than before.

    Apes shed pounds while doubling calories, researcher finds


    quote: “Although they take in twice as many calories on the new diet, after a year, the big boys of the primate house have dropped nearly 65 pounds each and weigh in the range of their wild relatives.”

    the study:

    Adiposity in Zoo Gorillas (Gorilla Gorilla Gorilla): The Effects Of Diet And Behavior


    (I haven’t read the 100+ pages yet, too busy)

    • Yes, very interesting. When our cat died of cardiac disease last year we couldn’t help but think we accelerated her demise by feeding her so much junk (mostly carbs).

  • Anon

    Can you comment on the following article decrying red meat at The Daily Telegraph? http://www.telegraph.co.uk/health/healthnews/9138230/Red-meat-is-blamed-for-one-in-10-early-deaths.html

    • I will not comment on this study now, other than to say this is yet another TRAGIC example of how “nutrition science” has run so far amok in this country over the past 50 years. This type of “study” is in a category of junk science known as observational epidemiology. I promise, very soon, I will devote an entire post to this important discussion.

    • Brad

      There’s a pretty fair critique of observational epidemiology at http://www.scienceboard.net/community/perspectives.26.html. On the one hand, observational epidemiology stands as the main “proof” of a link between smoking and cancer, but even its practitioners acknowledge its many weaknesses. The new study by Pan et al. did at least make an effort to statistically remove confounding factors related to the fact that people who eat red meat are more likely to also smoke, be sedentary, and be overweight; after removing those factors the associations between red meat consumption, cancer, CVD, and total early mortality still held up. But they’re still just associations and I’m not sure even this study, with its more than 200,000 participants and 2.7 million person-hours, can demonstrate causation.

      • Guys, if there is no control group (i.e., a group that does EVERYTHING else the same, EXCEPT the treatment) *and* “treatment” (e.g., eating red meat) can’t be prospectively isolated from all other variables, what we have is not called science. At best it’s called correlation.

    • Brad

      Okay, but you may want to acknowledge that this is an extreme view, and your definition of “science” would throw out entire fields of inquiry, such as climatology, where controlled experiments are impossible. We couldn’t even prove Newton’s law of gravity until the 1960s when we were able to travel somewhere with no gravity and thus perform the control.

      In the field of climate change, which is where I’ve worked for the past 23 years, we only have one Earth, whose climate is affected by many variables, none of which can be controlled for. You can easily demonstrate in a controlled lab experiment that increasing CO2 content of air causes it to warm in the presence of sunlight, but out in the real world the situation is far more complex. Climatologists have been able to use isotopic ratios to demonstrate that the increased concentration of CO2 in the atmosphere comes from burning fossil fuels rather than natural sources, and they’ve been able to use measurements of outgoing radiation at the top of the atmosphere to demonstrate that CO2 is indeed absorbing longwave radiation. And they’ve been able to pull together multiple lines of evidence to show that the Earth’s average temperature is increasing, not only based on data from weather stations, satellites, and balloons, but also from changes in phenology, growing seasons, glacial and sea ice extent, permafrost, and other sources. But because the climate is naturally variable, we can only say that the warming of the past 50 years or so cannot be explained by natural causes as we currently understand them. And because we can’t do a controlled experiment on the climate, we can’t definitively isolate CO2 and other greenhouse gases from the other factors that influence climate. So you won’t see responsible scientists claiming that greenhouse gases are certainly causing the current observed changes in climate: the official line is that they are “very likely” to be the main culprit.

      I don’t call that “junk science,” I call it “doing the best we can to understand how the world works given our limitations.” Getting back to observational epidemiology, in most cases we can’t run perfectly controlled experiments on humans because it’s unethical. You can perform experiments on yourself, but you’re a sample size of one. So observational epidemiology can give us clues about relationships, and the more sophisticated ones with large sample sizes (including the Harvard study) can perform sensitivity analyses on different elements of the diet and statistically exclude confounding factors. No it’s not perfect, and no it’s not definitive. But instead of dismissing it as junk science maybe it’s worth trying to figure out if there’s a way to better design these studies so they can arrive at more robust conclusions.

      • Hi Brad, thanks very much for your thoughts, which make a lot of sense. I don’t know enough about climate science to have (an educated) point of view on the science and limitations, but your assertions seems reasonable — you do the best you can with observation because it’s all you have. Same for Newton and Galileo.
        However, I’m not willing to give nutrition-based observational epidemiology such an easy pass. Here’s why:
        1. We CAN do better. We can do controlled experiments that isolate variables and prospectively randomize subjects.
        2. It is not unethical to do such studies. We have informed consent and IRBs for exactly this reason.
        3. I completely agree with your point that obs epi is great for generating hypotheses. That is wonderful. But here is where I find it unethical: these hypotheses get pedaled as “science” by the folks doing the work and the science journalists who report on them.

        Brad, it’s this last point that CAN NOT be overemphasized enough. Clearly you are a smart enough person to read a NY Times article about how Harvard has “proved” red meat is bad and know the limitations of the work. But how many people have your luxury? Does the average American? Does the average policy maker? I posit that they do not. In fact, if you look at the dramatic changes in US food-policy from 1972 to 1980 it is clear that virtually all of it was based on flawed science — observational epidemiology — just like this study.

        We are gambling with people’s lives because we confuse something that is NOT science with science. Perhaps I’m being too harsh calling it “junk.” I’ll accept that criticism. However, I stand firmly committed to making sure people understand why this sort of work is NOT science, why we CAN do better, and why it is unethical to to continue propagating this information as “science.”

  • Andrew Smith

    Your talk of “Ingested calories – digestion, exercise, daily activity and basil expenditure” seems like it may be seriously incomplete.

    How about waste material? Do urine, feces and sweat have zero calories? I’ve never read anything one way or another but it would seem to me that it’s certainly possible that many people’s bodies simply discard calories they don’t need and that they may discard more, even if calorie intake doesn’t vary, based upon the types of foods they eat.

    Has anyone examined this? If not, why the presumption that no calories are just thrown away?

    • You’ve failed to read the full paragraph… “Digestion” includes waste (i.e., undigested material). Quote:

      Now let’s be even more specific on the “expend” part of the equation. We expend energy in four ways: Digestion (all the energy we require to break down food, plus the undigested portions that leave our body); Exercise (everyone knows what this is, but I tend to separate it from daily activity since people really like to focus on exercise); Daily activity (the non-exercise activity we carry out); Basal expenditure (the energy we expend “underlying” any activity – e.g., when you are resting).

    • Andrew Smith

      Sorry to have missed that phrase, but even that doesn’t explain it enough for me.

      How much leaves with waste? Does it vary a lot by person?

      Most importantly, do people who are thin but eat reasonably high calorie diets simply excrete more of it, whether their bodies say, “I don’t need this energy so I will discard it.”

      If there’s any research on this issue, I haven’t read it and it seems to me (a total layman) the most likely explanation for why some people take in a ton of calories, don’t exercise so much that they obviously burn a ton of calories and yet still stay thin.

      • Andrew, these four “sinks” vary enormously by person, diet, and (obviously) activity level.

  • Mark Deevy


    Excellent Blog(s), in nk 8 months and have found the whole experience life changing.Just a couple of queries on Sodium:

    One can get sodium in different ways, sodium chloride, sodium selenite, is one a better way than an other?

    Can you get sodium on its own?

    Has chloride (too much) a negative effect on the body?

    Any thoughts would be greatly appreciated.

    Keep up the excellent work!


    • Mark, sodium is available in a number of ways. I prefer sodium chloride, because (I’m oversimplifying a bit) my body needs sodium and chloride in similar amounts. I can’t say, however, that I’m an expert on sodium, so I’ll probably need to spend some time getting buff on the nuances and data surrounding each option.

  • Showing recent comments and providing a link is a great idea. But I’m finding that the links do not take me to the specific comment, they take me to the beginning of that particular post, leaving me to sort through as many as 173 comments. I hope your webmaster can improve this link function.

    • I’m working on it, but there does not appear to be a “solution” that fixes every issue. I hope folks can be patient and realize this is just a hobby for me.

    • Travis Koger

      John, there is an issue with the comment link. I find that it works sometimes and others it doesn’t. However I just search for the text in the comment using the Ctrl-F or Cmd-F (Macs) in Chrome and it gets me pretty quickly to the one I am looking for.

      Keep up the good work Peter, don’t spend too much time fixing bugs in the blog and I for one would much prefer you to be spending your time answering the great questions here with equally great answers.


      • Thanks, Travis. I’m clearly an amateur-hour blogger at this point, but I would prefer to focus the limited time I have to blog on content. Appreciate the understanding.

  • Sharon

    Read your post then saw this in the NY Times:http://well.blogs.nytimes.com/2012/03/19/calories-are-everywhere-yet-hard-to-track/?ref=health

    My head is spinning from the contradictions! As a big fan to Mr. Taubes, I’m sticking with your analysis.

    I’m sure you have something to say about this statement: “They found scant evidence to support the popular notion that any one nutrient is responsible for our obesity, or that a low-carbohydrate diet is everyone’s secret to success.”

    • Hopefully this week’s post (while not on this topic) will start to arm you with the tools to discern this sort of stuff. You don’t need an MD or PhD, just careful attention and an understanding of what science is (or is supposed to be).

    • Brad

      There’s actually an entire chapter in “Why Calories Count” (the new book by Marion Nestle and Malden Nesheim) devoted to debunking Gary Taubes, citing the famous Twinkie diet among others, and noting that most of the studies cited by Taubes suffered the same shortcomings as observational epidemiology studies in that they relied on self-reporting and rarely collected information about calorie intake. The book cites studies done with doubly labeled water that “make it clear that heavier people eat more calories than their lean counterparts but tend to underreport their caloric intake to a greater extent.”

      Basically their thesis is that obesity is complex problem that cannot be boiled down to a single cause, and they strongly contest Taubes’s assertion that the kind of calories consumed matters more than the amount.

      • Hmmm. Sounds a bit confused to me, Brad. Doubly labelled water is a (very elegant) technique for measuring energy expenditure, not intake. Furthermore, the Alternative Hypothesis that Gary and I find compelling does not imply that overweight people eat less than or the same as lean people (though some do). It says the balance of calories is not the driver of weight gain, it’s the result.

    • KevinF

      Sharon, I don’t see much in that article to oppose what Taubes or our Dr. Attia say, aside from the gratuitous zingers at the end dismissing low-carb diets. (And as I’ve learned, Jane Brody is notoriously on the wrong side of the carb issue.)

      Please note that every single super-high-calorie example Jane Brody gives is in fact a high-carb treat. Pizza, bagels, cookies, soft drinks, dessert.

      The problem of grazing all day at Staples and Bed, Bath & Beyond — yes that’s what people do in response to carbs and blood glucose swings and insulin. I’m 3 weeks into severe lo-carbing and I’ve been shocked to find I have no desire for carbs. I even refused birthday cake last week. And it wasn’t an act of discipline — I simply had no interest. You might as well have been waving cardboard under my nose. Maybe there’s something to this…

      I haven’t read the Nestle and Neishem book (Nestle? That’s irony!), and it looks like it’s not going to be a low-carb manifesto. But I’m wondering if they ever get clued into how carbs make you eat more and how lo-carbing suppresses hunger.

      Towards the end:

      “The long-term effectiveness of low-carb diets for a vast majority of people who try them has yet to be assessed.”

      Logically this is something that can never be assessed, since obviously the vast majority of people who try low-carb diets are not doing it as part of a formal medical research project. Think about hwo empty that sentence is.

      Further, most of the medical establishment doesn’t seem to want to “assess” this issue. How is that possible? What the heck ARE they doing? It’s as if they’re afraid of what they’ll find out.

    • Brad

      By the way I didn’t mean to imply that I think they successfully debunked Taubes, only that this appeared to be the goal of that chapter in the book. It might be worth taking a look at what they wrote at some point for a rebuttal, although it may be that all the counter-arguments they offer have been published and addressed previously elsewhere. As I’ve said before I’m an agnostic on all this.

      Also for KevinF’s benefit: note that Marion Nestle’s surname is pronounce “nestle” as in “the cat nestled among the pillows,” not “Nest-lee” in the giant candy-bar company.

  • tim

    great stuff Peter. So, 1st we had the Harvard observational study. Now a new study shows that white rice causes type II diabetes. Ok, science, which is it, red meat is bad, rice is bad too? I work in the diabetes field and I can tell you what causes weight gain and it isn’t a big fat steak! It’s insulin, endogenous or exogenous.

    I’ve started cutting out my carbs slowly the past week and adding in natural high fat meats, cheeses, etc. What I’m finding is, no surprise, that I feel a heck of a lot better after the low carb meals. And I’ve restarted jogging and found that my energy is not crashing midway into the run, 3 hours after a low carb meal, whereas I used to crash 20 minutes in after “carb loading”.

    Anyways, glad I discovered your site. You are changing minds, one person at a time.

    • All of these studies are observational. Stay tuned for another 24 hours and you’ll get all the answers you need with respect to interpreting these studies.

  • Scott B

    Hi Peter – I’m not sure I follow all of what you’re saying about calories. If I understand correctly, I think the following principles are true:

    • If you have gained weight, you’ve overeaten to do it (where overeating refers to positive energy balance).
    • If you undereat, you will lose weight regardless of your diet composition. Call this the “desert island” effect. Once rescued from the island, you will gain it all back plus some.
    • Eating carbs encourages you to overeat, because of the blood sugar rollercoaster.
    • Eating carbs drives fat storage through the effect of insulin on your fat stores.
    • Eating carbs drains you of energy, encouraging you to be sedentary.

    So if the above is right, here’s my question(s):

    1) If you overeat on a low carb, high fat diet, will you gain weight?
    2) If you are in energy balance on a LCHF diet, will you lose weight?
    3) Do you have to undereat to lose weight regardless of your diet? Is is just easier to do so on a LCHF diet?

    • I think you’ve almost got it. The other thing, for many people, that occurs with high-carb eating is a variable reduction in metabolic expenditure. I used the word “variable” for a reason, as it seems to vary from person to person.
      To your questions:

      1. Depends how much, and in my experience, most people will eventually gain weight if they go out of their way to eat as much fat and protein as possible. However, it seems about a third of people who cut carbs end up INCREASING total caloric intake, while improving energy balance. I do not know why, though.
      2. By definition, if you are in energy balance (i.e., energy in = energy expended via the 4 methods of expenditure), you will maintain weight (fat weight, at least).
      3. Semantics make this tough…technically, YES, you need to under-consume nutrients relative to your total expenditure (ALL 4 means of expenditure), but this does NOT always mean eating less than before or eating less than presumed/measurable “activity.” That said, in my experience, about 2/3 of folks who give up carbs just seem to eat the same or fewer calories overall compared to when they were carbivores.

    • Debbie

      I’d like to invite readers of this site to check out The New York Times magazine. Go to the Times online, and click on Sunday Magazine in the left hand column. They are sponsoring an essay writing contest: Why It’s Ethical to Eat Meat in 600 words or less. And the 800 comments following the contest invitation – oh boy.

    • Scott B

      Thanks Peter. I think with my questions I started to slip back into the “Calories In, Calories Out” nonsense that has caused so much trouble. I think you’re saying that it’s true (generally) that if you eat more calories than you burn you’ll gain weight. But this is really an empty statement, a distraction, one that begs the real question, which is “Why do we overeat?”. Answering this question is the key to understanding why we get fat. Worse, “Calories In, Calories Out” misleads us into thinking what we need to do is eat less and exercise more, without accounting for the fact that these are dependent variables. We can’t eat less long term because of the scourge of hunger. And we can’t work out more without stimulating our appetite. So the game is all about eating less of the things that make us fat – carbs and more of the stuff that makes us feel full – fat. I think I get it now . . . ;).

      • Nice work. It’s worth taking the time to struggle with theses ideas. I’m glad you did and I hope others will do so, also.

  • Dave


    I appreciate all of your writings here (especially those relating to exercise physiology as they directly relate to what I’m trying to do), but I’m still skeptical that insulin is truly the culprit in unwanted weight gain. First I will say that I agree 100% that being overweight/obese is driven by the body through hormones, and not a psychological disorder or a matter of willpower. I also agree that Cals In/Out is an accounting model just showing what happens to energy in the body, but that’s about it. Anyways Stephan Guyenet, James Krieger, Lyle McDonald, and others seem to think insulin plays almost no role as a causal factor in obesity. It simply does what it is supposed to do based on the energy inputs fed into the body. So I’m not sure whether to believe that insulin causes obesity, or whether leptin, grehlin, the brain (hypothalamus), and food reward cause obesity at this point.

    Anyways I am similar to you in that I am an endurance athlete who couldn’t seem to lose the gut no matter how much I exercised as long as I was eating a high-carb diet. The question I have is whether you measured your insulin levels during this diet change process to verify that you did in fact have elevated insulin levels that would make it difficult to lose weight.

    I ask the question why aren’t there studies that take people like us (with very moderate metabolic defects, but otherwise healthy) and monitor our insulin levels when going from high-carb to low-carb, and again going from low-carb back to high-carb? That seems to me it would be a smoking gun in proving that insulin does cause obesity.

    • Dave, Stay skeptical, my friend. Just make sure you are uniformly skeptical until you gather information. I’m quite familiar with the food reward ideas, and I think they are valid, I just don’t believe they are the “first order terms.” I think, for most people, that insulin is the first-order term, but this does not diminish the importance of other factors, of which food reward may be another.

      Yes, I did measure insulin levels and insulin responses (to OGTT, for example). You can see this in my personal journey, section 3, I believe. And I’ve seen it over and over again in everyone I work with. When the carbs go away, the insulin levels (both fed and fasting) go down, the fat goes away. This fact alone does NOT *prove* insulin is the causative agent to being fat, but when coupled with a lot of other information and data paints the most compelling story I see out there.

      The good news is we can study this and we will. This is one of many questions to be tested by NuSI.

    • Dave

      Thanks for pointing me back to your journey writings. I read them early on, but I think at that point I didn’t have the understanding of what I was reading. This really helps reinforce the idea that insulin does matter. Especially for someone who isn’t morbidly obese or have any obvious symptoms besides carrying some extra weight.

  • Diane

    I realize I am late to this topic but I wanted to share that I spent 3 months backpacking in the wilderness traveling about 20-30 miles per day. I did this twice. Both times I lost weight in the first few weeks then slowly began to gain it back. The 2nd time the gain was worse despite the fact that I was hiking more miles per day than the first time. Both times I ate mostly carbohydrates for food, with some fat. My diet was basically cookies, crackers, candy and pasta with a small amount of cheese and tuna. I was always ravenously hungry. This experience ruined my metabolism and left me insulin resistant. I gained weight at an alarming rate upon return to civilization. I had to go low carb to stop the weight gain and restore my appetite to a measure of sanity. I learned that calories in/out is too simplistic. Next time (if there ever is one) I will bring more meat and fat and way fewer carbs and hopefully be able to maintain my health during and after. I’ve found doing experiments with shorter backpacking trips that my appetite and energy are far better when I can use ketones for energy rather than dietary carbohydrate. Thank you for your informative blog!

    • Thanks for sharing your experience with us. This is a pretty common scenario.

  • Stanley Frank Young

    Unbelievable… Marvelous in the extreme…
    Peter… Your succinct … thoughtful… clear…
    I have hungered for so long for You and Gary and all the rest… near and far… ages past and present… to actually get down to the real science behind all of this.

    I am convinced that the 168 million tons of Sugar production worldwide… will quietly find its way into fewer and fewer mouths.

  • Annette

    Thanks for all this very useful info..
    My question– so what happens when/ if one is on a low carb diet and goes overboard with the Fat intake ? Surely this will also lead to weight gain ? This speaks to my always doubting any fat loss strategy that ostensibly relies on the ‘eat as much as you want’ paradigm

    Cheers very much

    • KevinF

      I can partially answer on behalf of those of is who DON’T eat 4,000 calories a day. People don’t understand the implication of “eat as much as you want”. What very low carb dieters often find — and I certainly have — is that your hunger diminishes to a degree you’d never imagine. Between the high satiety of fat & protein foods and avoiding carb-induced spikes and plunges in blood sugar, you just don’t need or want to eat much.

      I’d always envisioned Atkins dieters (for example) tucking into a 6-inch stack of hamburger steaks covered in cheese sauce. But fact is you just don’t eat like that because you don’t have any desire to. For me, eating as much as I want typically means 300 – 500 calorie meals and little or no snacking.

      I’ve quite naturally settled into a daily calorie range of about 1600 – 1700 cals a day (I’m a 220 lb guy) without trying. Except on weekends, when I usually don’t bother to eat “breakfast” until 3 pm and so, and I end up eating one or two meals that day. And I’m pretty sure it would be easy to eat less if I wanted to, but I don’t want to stunt my metabolism.

      And unlike all my co-workers I skip the leftover pizzas and baked goods people constantly leave in the break room next to my cubicle. It’s not an exercise in willpower. That stuff just doesn’t seem like food to me any more than the boxes they come in. From what I’ve seen on blogs etc I’m pretty sure my experience is typical, though athletes like Peter often eat more.

  • Stan

    What I don’t get is why does the process of weight loss stop before you have lost all the fat that you want to lose? I started at 200lbs and 35+% body fat. I effortlessly lost 40 lbs, and then hit a plateau. Can’t seem to get below 160 lbs and 23-25% body fat. My insulin levels were low enough to lose all that fat; nothing changed, so why doesn’t the fat continue to fall? After all, as Taubes points out, Type I diabetics without exogenous insulin become emaciated. I should be ripped by now, with a 6-pack. I don’t understand how my body can defend such a high percent body fat while eating a low carb regime.

    Also, I don’t understand the evolutionary basis for the alternate hypothesis. Acording to the paleo folks,we evolved to do well on high fat, moderate protein diets. Yet the ability to store fat during periods of abundance is essential to survive in a world where food supply was irregular and uncertain. So why would it be difficult to gain fat on that normal high fat, moderate protein diet?

    • Stan, no one knows the answer to this obviously vexing problem. A T1D literally has ZERO insulin. Conversely, a non-T1D still has insulin and therefore is still metaphysically able to carry about anabolic functions (e.g., build muscle, store glycogen, store fat). As much as I believe insulin the “general” in the fat army, there are other soldiers, too. You should obviously have your insulin resistance checked (HOMA-IR, LP-IR), but you may also be leptin resistant. I don’t know (or want to know) how old you are, but it’s likely that your endocrine system has a set point for fat metabolism that could take years to reverse or re-set. I have noticed this extensively in my practice. Someone who has been 25-50% body fat for much of their life has a harder time losing the fat than someone who was, say, 15-20%.
      To your second question, don’t confusing storing a healthy amount of fat, say 15% of body weight, with what we do today. There is no evolutionary advantage to be insulin resistant with 35% body fat. It makes other aspects of primal living difficult and promotes little evolutionary fitness.

    • JLMA

      Your comment is from 13 months ago and I wonder if during all this time you managed to go below 23% body fat?
      And, if so, what did you do to continue losing fat?

  • Lisa

    Hi, I have been low carb for about 3 months with no change in weight. I feel great, but how do I know what fat/protein/carb ratio will work for me? I’ve heard 60/35/15% and I feel I need to be at 1200 cal a day to lose, which is a challenge.
    I’m 5’3″ 157 lbs. 50 yrs old female.

    Is there a formula?

    Thanks, lisa

    • No formula, unfortunately. Everyone is different and the requirements depending on so many factors, especially where the calories come from.

    • Ellen Urciola

      Hi Lisa,
      Here is my two cents (for what it is worth). I am a 54 yr. female who currently weighs 223 (down from 227 just 6 days ago).
      I too have struggled with this fat to protein issue. Carbs are not an issue since I have been 98% carb free (and loving it) for 18 months now. I initially went from 237 to 220. Then I tried adding back “healthy carbs” (Greek yogurt, nuts). I promptly gained 7 lbs. in 3 months.

      I have just recently begun to lose weight again still sticking to a very, very low carb, high fat diet. With me there is a certain amount of hunger involved (probably because I am in panic mode since my doctor increased, instead of decreased my Lisipril. I am resolved to get off my HBP medication). When these “guys” say, stop when you are full, I literally took it to mean I could eat six hamburgers (a slight exageration of course). Now, (after numerous post readings, I have come to interpret it to mean when you “just get full.” With me, I cannot yet indulge in venti latte’s (a future goal), but I do have my coffee with steamed heavy cream first thing in the morning. I have found that I have to limit the amount of heavy cream I intake. I get my fat mostly from olive oil and butter (but again, I had to stop eating pads of butter and learn to recognize when I was “Just Full”)
      Currently, I am following the Duke University suggested plan that Gary Taubes published in hie “Why We Get Fat” book. I am not suggesting this will work for you, it is just how I am proceeding. Good Luck. (Also, check out Dr. Mary Vernon, her tip for snacking (that works great for me) is to carry hard boiled eggs [allowed in unlimited quantity in the Duke plan]).

  • Kathy

    I’d be very interested to hear your take on this study. This is just a report of the study. One of the points I find interesting is that they claim low-carb diets cause inflamation.
    No matter, at least they’re making the point that not all calories are created equal.

    ScienceDaily (June 26, 2012) — A new study published June 26 in the Journal of American Medical Association challenges the notion that “a calorie is a calorie.” The study, led by Cara Ebbeling, PhD, associate director and David Ludwig, MD, director of the New Balance Foundation Obesity Prevention Center Boston Children’s Hospital, finds diets that reduce the surge in blood sugar after a meal–either low-glycemic index or very-low carbohydrate-may be preferable to a low-fat diet for those trying to achieve lasting weight loss. Furthermore, the study finds that the low-glycemic index diet had similar metabolic benefits to the very low-carb diet without negative effects of stress and inflammation as seen by participants consuming the very low-carb diet.

    • Already addressed briefly in other comments today. Longer follow up at a later date.

  • Kathy

    oh, shoot, I missed it – I find it hard to keep up with all the different threads. Is there an easy way to keep track of the most recent posts without visiting all the different topics? Sorry, I don’t spend a great deal of time on these kinds of sites, so I’m not terribly fluent at the mechanics. If the answer is an RSS feed, I can’t do that, so maybe I’m out of luck.

    • Bob West

      Hi Kathy,
      You can use the excellent “Recent Comments” list that appears on the right side of every page, part way down. That’s how I keep up (that’s how I found your comment 🙂 ), and it saves a lot of time.

  • Kathy

    Thank you! I knew I must be missing something obvious….

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  • Bill Berry

    Okay…I read “Do Calories Matter” three times…and I’ve gotten the gist of the article but let’s shed the science for a moment and talk common sense; you cannot eat an unrestricted number of calories regardless of whether we have the discipline to eat zero carbohydrates day in and day out; true? There is a number that implies that an individual can gain weight if enough calories are consumed; yes?

    • Certainly, one could have force down an unrestricted amount of fat and not gain weight. To do so, one would have to believe that your body would need to “figure out” a way to dispose of the, say, 20,000 kcal per day you ingested. Realistically, I can’t imagine the body could increase TEF and REE enough to do this. That said, in my experience, about a third of people LOSING weight on a low carb diet *actually* find themselves taking in more calories than they were taking in on a high carb diet, by as much as 30%. The implication, according to the First Law, is that in these folks — at least for some period of time, TEF and REE have increased.

  • Leez


    About six weeks ago, I turned the light on to keep the CW/SAD monsters under my bed from nipping at my heels while I made a slow transition to an LC way of eating. Stumbled upon your website last week; needless to say, I can’t put this ‘page turner’ down. I appreciate the need to read before posting; however, when I enter my issue in the search field, there are a couple of hits, but I can’t seem to find an answer to my experience regarding bowel movements and LC.

    I did find where you mentioned that BMs on an LC regimen are more healthy for you personally now than pre-LC (I don’t remember your exact phrase). My distress is that my pre-LC BMs were consistent and substantial 2-3x/day; but during the last month, that function is once every other day and puny at best. 🙂 Intuitively I think it is due to the lack of fiber in my diet, yet I don’t know where to find the fiber without consuming veggies/fruits. Is it just a matter of time while my body is adapting?

    Also, in one post you were asked about carbs vs net carbs. I believe you responded to the effect that you logged the gross (I don’t know what label to give them!) carb figure when doing your intake calculations instead of the net carb figure because…? it was good to know that you had a buffer? This has my chain wrapped around the tree because my gross carb figure sometimes pushes my intake to >50g, while the net figure keeps me <50g/day. I'm living/working in the middle east and haven't yet come across any marketplace vendors hawking Ketostix, hence my obsession with wanting my numbers to be 'right' since right now they are my only standard of measure for that haloed ketosis state. While I'm peddling as fast as I can, I'm not yet at a place where I can get much lower than the 50g/day mark. I suppose I just have to have patience on that account as well.

    Well there ya have it. I've probably answered both of my issues in a word: PATIENCE. Otherwise, I am glad for any insight. Thank you for your time!


    • Leez, the whole “50 gm/day” thing ONLY matters if you’re trying to be in ketosis. Many people do exceptionally at higher levels of carb intake. If you want to be in ketosis, the best thing to do is just measure it. Otherwise, don’t stress about it all. As you said, a little patience…enjoy the journey.

  • Leez

    I was thinking that to be in ketosis (keto-adapted?) was the prefered state. I’m trying to keep up with the big dogs without being house-trained. Time to throttle back so I can enjoy the journey; thanks.

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  • Fiona

    Hi Peter

    Thank you so much for your wonderful site and all your hard work!

    I have just started studying Nutritional Medicine and all of my standard texts push the low fat, calories in / calories out line. A tad depressing but I am plunging onwards nevertheless!

    I *think* I fully understand your explanation above, but I just want to query how your explanation differs from Zoe Harcombe (whose work I have also been enjoying immensley). She appears to explain that the Laws of Thermodynamics do not apply to the human body due to us not being a closed system, and you appear to be explaining that we can equate the various ways we have energy expenditure ( (exercise, basal expenditure, digestion etc) into an overall energy-in, energy-out equation.

    Sorry if I didn’t explain this properly! I am just seeking some clarification – do I invoke the 1st Law in my essay or not?!! lol. I am sure I am missing something simple – I would be most appreciative if either yourself or one of your learned readers could set me straight!

    Many thanks!!

    • The First Law *only* applies to closed systems. A system being “closed” is a function of where we draw the boundary conditions. When you include all the energy entering a system and leaving a system — even one as complex as the human body — it’s closed, and therefore the First Law applies.

    • Fiona

      Thank you so much for your quick reply! Most appreciated.

      As an aside – I have been reading your experiences of being in ketosis with great interest. My young son suffers from a very severe and complex seizure disorder and has been on the ketogenic diet for over 2 years. The diet reduced his seizures by 90%. The hardest part of the diet for young children is getting them to keep weight on – and this for a severely disabled child who is not running around or moving much at all! I always laugh when people ask about his diet (he is on a 4:1 ratio) and they say “gosh! How can he be so little when he eats so much fat?!”

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  • Ellen Urciola

    Hi Dr. Attia,

    Thank you so much for the chance to “give back.” Two comments and a question sir.
    I have finally managed to find my optimal fat/protein percentage and it is thanks to one pivitol comment you made to a reader above. A kind of “duh” moment for me. in essence you commented to a reader that if you were to consume more fat than your body could burn, it would get stored as fat. Armed with that I started meticulously recording calories, protein, and fat until I started burning stored fat (I should clarify, the calorie count was necessary to calculate the fat,protein not to restrict calories). Now that I have dropped under 220 I would like to start exercising, but am afraid it might be too early, plus I have low back problems. My question is, can you recommend a website or book/DVD to strengthen lower back? I do love to exercise.

    • Thanks so much, Ellen, for your support. Check out the work of Brian Dorfman (www.briandorfman.com). Brian is one of the most talented kinesiologist I’ve ever met and he and his team are an integral part of my training. Most people don’t know this, but I had a debilitating back injury in 2000 that left me unable to walk for months and required a year of intensive rehab just to move properly again. Today, I can do just about anything, but it’s required a profoundly deliberate change in how I move and treat my back.

  • Ellen Urciola

    Wow, that makes what you do even more amazing. Thanks for the website lead, I went with the lower back basics. I talked to Nicole Dorfman. She was very helpful and even asked me to call back if I had any questions about the exercises. You do not get that kind of support in today’s world.
    Thank You

    • They are best in class, to put it mildly.

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  • Mark Hoheisel

    Great blog! This seems like an extraordinarily important topic for something so little discussed.

    Gary Taubes footnotes make it pretty clear how this current dogma is used as a foundation for the mainstream position. Hey if calories are calories then the fact that fat has a lot more calories per gram makes it the prime suspect in obesity…which is clearly correlated with all those diseases of civilization that are breaking the medical system and threatening the whole economy.

    It does seem like a perfect set-up though for simple robust repeatable experiments with unambiguous results.

    If calories are calories, then for most any human participants in a random assignment experiment…overfeeding should have the same results regardless of the nutritional proportions.

    If you have a low/fat high carb group, a high fat/low carb ketogenic group, and a “balanced” group…and you establish individual baselines for calorie levels at a stable weight for all three groups…you can expect that if you bump the calories up to 150% or 200% of baseline everygroup should put on fat at roughly same rate overall. Participants in Ketosis at 6000 calories per day should put on fat about like a Particpants drinking pepsi and eating plates of spagetti at 6000 calories per day ….

    I’d bet on some pretty low probability scores for that with just about any particpants even for small groups. The individuals will of course vary quite a lot but ya think those groups will look the same? Intuitively it seems an easier experimental intervention to look at fattening rather than the traditional reducing diets. As far as trashing the hypothesis they ought to be the same.

    • Mark, our first NuSI-funded experiment will test this very question.

  • John G.

    Dr. Attia,

    Was wondering if you could answer a question for me? I’m at about 13-14ish bodyfat % and am having a heck of a time going lower. It seems that when I drop my kcal levels my metabolism actually slows down, and even though I’m eating LESS, the fat doesn’t budge. Also, I try to keep my carbs <50g daily. My exercise is as follows: Resistance training 3 X per week (heavy, compound lifts only) and approx 20 min of running or sometimes sprint intervals, maybe twice a week. Any advice? Btw, I'm 40! 🙂 Should I drop the kcal and do more cardio?? More aerobic? Longer duration, more frequently? I don't want to look like a marathon runner. Sprinter look is good! Trying to preserve lean muscle while cutting fat. ANY thoughts shared would be greatly appreciated. I find your site to be quite informative and very easy to read.


    John G.

    • John, it’s really impossible for me to troubleshoot these things in this format. Far too many questions I’d need to ask to provide any meaningful information.

  • Steve

    Excellent blog. May I first apologise if you’ve already covered my points – there are a lot of responses here.
    When I started exercising properly, after months of doing very little, I found that initially my weight actually increased. People kept telling me that it was because I must be eating more, but I know this wasn’t true. I almost felt (and you can correct me) that my body had gone into a different state, hoarding more of what I ate and drank. After several days I did start to lose some weight but not much. Then I stopped for a few days and the weight fell off.
    So there’s definitely more to it than the common perception.

    I’ve also got 2 daughters. One is more athletically built than the other. It’s just the way they came out. She also happens to be the one that likes vegetables and lean meat and doesn’t like cake. I’ve always wondered what the relationship between the natural athleticism and dietary habits was. I’m pretty sure the diet didn’t come first.

  • Nutrition science

    Just to correct an error in the section “Key concept 1”, kcal and calorie are not the same, and no one who knows better uses these interchangeably. If you notice on a food label that calorie is capitalized “Calorie” that is the important thing. Capital “c” Calorie and kcal are the same. So 1000 calories equals 1 Calorie equals 1 kcal. This is day 1 basic nutrition science (and no I won’t use quotes- sorry!).

    • Yes, you are correct. Thanks for pointing this out, though I’m not sure how this changes the point of the post. Was your sarcasm supposed to undermine the point of the post, or did you just feel like adding gratuitous value?

  • Nutrition science

    Just making a joke- sorry it fell flat. Although I’ll admit its a bit disappointing when basic concepts are presented in error from an expert.

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  • Adam

    Dr. Attia,
    I first wanted to say thank you for helping me achieve a new quality of life after adopting a low-carb lifestyle. I’ve struggled with this my entire life, and it’s great to know that my problem of carbohydrate-intolerance is diagnosable and treatable.
    I had initially dropped ~35 lbs. by just cutting calories and running, but eventually the weight-loss stopped. I still had to eat constantly because I was always hungry even though I was eating fruit, oatmeal, etc. It was still too many carbs for me ( looking in hindsight ) even though most were “good” carbs. After switching to a plan similar to yours, and using alot of the guidance from the book “The Art and Science of Low Carbs for Performance”, I managed to continue weight loss ( another 15 lbs. and counting ). For the first time in my life I’ve achieved a 10% body fat level.
    I went to see a nutritionist to get a second-opinion about what I was doing to make sure I wasn’t doing anything harmful or missing anything in my diet, and fortunately I was able to find a Low-Carb knowledgable nutritionist. She said that I was the healthiest person she’d examined in a while, but she did warn me about letting my body fat % getting to low.
    So I guess my question is, how low is too low? I still seem to be dropping lbs, and I do keep pretty satiated throughout the day ( so I’m not starving ). Will my body naturally plateau at a safe level; do I have to increase calories?
    Thanks again, and keep up the great work!

    • Congratulations, Adam. The “how low is too low” question depends on many factors, including age, sex, and activity level. For a very fit and active male, 7-8% is probably safe. Much below that, and you may (though I know folks who walk around lower without any issues) have trouble.

  • Peter

    This may be a bit late but this post seems the one most related to my question.

    It maybe naive but I have trouble with the relevance of the First Law to weight loss. It is an approach used throughout the nutrition industry but one that, as a physicist, I have a basic issue with. Fundamentally – A Calorie is not a measure of mass. There may be a correlation between energy balance and body weight but, to me, the connection is non-trivial despite everything (literally) that I have read blurring the line between them. Indeed, the way I read this post and others in your blog, it appears that that is also your point – all calories are not equal.

    I would have thought that a more appropriate starting point would be conservation of mass, not conservation of energy. Of course, then you need to consdier solid, liquid and gas intake and outflow taking the discussion to an entirely different level.
    Hence there is a simpification here – equating the energy difference to stored fat. It allows you to ignore temporary fluctuations due to liquid or gas exchange – which swamp body mass studies in short time scales. But it also ignores the bio-chemical processes involved in converting various nutrients into fat – or the involvement of other tissue types. And the removal of metabolic by-products is not as simple as ‘energy’ being ‘burnt’.
    As you point out, there is a dependency between input and output which is commonly skipped over.

    In short I would be interested in your view, or any studies you know of, that verify that the simplification is valid and that significant factors are not being missed because the physics is being blurred.
    If nothing else it seems to me that this would back up your argument that calories are not the important point, but rather the way the body deals with specific nutrients.

    • Read Richard Feinman’s (not Feynman) piece on the Second Law.

    • Peter

      I assume you mean the 2004 paper in NutrJ?
      Interesting – and the argument about the 2nd Law is plausible. But it, and everything else I have read make implicit assumtions about how the 1st Law applies.
      That is *does* apply is certain and the equation “E(stored) = E(in) – E(out)” is a fair representation. But the next step in the chain of thought appears to a “lie to children” – a useful approximation for beginners until a deeper understanding is achieved. In this regard I would have thought it would be abandoned at the deeper biochemical discussions.
      The implicit step I am referring to is the mapping of the above variables to aspects of nutrition.
      * E(in) = energy consumed seems correct on the face of it (which, as a scientist, means it needs to be treated with suspicion). I can understand that there is little energy extractable from water or oxygen and so food can be considered the only source.
      * E(stored) = fat seems to me to be useful as a first approximation since my understanding is that other storage mechanism (e.g. glycogen levels) have limited capacity and are usually full.
      * E(out) = energy expended is the most unlikely bit but I am not enough of a biochemist to be certain. Is there no potential energy passing out of the system unused? Lipids in feaces or sugar in urine etc. I have seen no talk about the energy content of metabolic by-products.
      All three of the above are skipped over in everything I have seen and I wonder if there is something in the gaps which might be useful in understanding.
      As I said – conservation of mass, at least to me, seems much more applicable than conservation of energy and more useful as a starting point.

      Apologies if this has drifted somewhat. I am still trying to work this out in my own mind and you appear to be much more deeply involved in the relevant issues than anyone else I have contact with 🙂

      • E(in), as you said is all accounted for by food intake. E(stored) is all stored energy, which includes fat (the most abundant), but also muscle and glycogen. E(out), or TEE, is composed of REE and TEF, along with deliberate work. My post on “good science, bad interpretation” explains this in detail. TEF is what you’re talking about. This includes the energy cost of digestion and also includes energy that leaves the body (methane, fecal fat, and urinary and breath ketones when appropriate).

    • Peter

      Okay, I understand the connection but I am going to have to think about the implications in bit more depth.
      I still find the conservation of mass view easier to understand conceptually, but mostly I think because of the short cuts taken in describing the conservation of energy view. The latter is certainly a much more common approach.

      To explain where I am coming from: both energy balance and mass balance provide (different) holistic views of the human body as a system – with biochemistry and physiology providing the ‘zoom-in’ detail.
      What I am trying to do is meld them all into a consistent mental model – at least for myself.

      I appreciate your help in explaining

      • Energy is the better way think about it, but another person worth reading is Andrew Lyon, professor of chemistry at Georgia Tech. He writes here: http://lyongroup.net/
        Andrew is exceptional and is working on a piece addressing this very point. I don’t think it’s up yet, but I’ve seen drafts.

  • Catherine

    I really beg you to try eating 100% alkaline for just at least 5 days and see if you only lose body fat. I feel so strongly that this is the answer to fat loss. I have really come to believe like you that fat is NOT a calorie problem. However, you think it stops at insulin resistance. I think it goes a step further because an insulin spike is a result of having acid in the body. Sugar is acidic to the body and when the body has too many acidic foods, it stores fat to protect the organs from the acidty. It’s not just trying to say “I’m going to make you fat because you ate sugar and are a greedy pig”. It’s saying “There is too much acidity in the body and i need to protect these organs”. You could eat as many calories in alkaline food as you liekd and still lose weight. Fruit is not alkaline, green vegetables are. Helathy fats are. Meat,Dairy,Refined Carbs, Grains, water without lemon or apple cider vinigar can be acidic to the body. Please just try it for five days. I think hemp protein is alkaline if you need protein for your workouts. Find an alkaline off robert young’s website because he has the most accurate one. Other people tend to let fruit, some nuts, and carrots, sweet poatoes go on the alkaline list when they are acidic. I know you think this is crazy but you have to be open minded and try it just to see if it works and not be ignorant.

    • What are the most convincing data on this topic? I am not familiar with RCT’s testing this.

  • andy tubbesing

    You can’t win. You can’t tie. You can’t get out of the game. If more folks understood thermodynamics we’d be better off. Thanks for another great article.

    But I get a little nervous when I read, “Obesity is a growth disorder.” Not because I think you’re wrong, but because, especially in our current entitlement society, it gives an excuse. I know a lot of people who already blame their obesity on ANYTHING other than their personal choices. They’d gobble up a “growth disorder” soundbite.

    Keep up the good work, and thanks again.

    • Donna

      I would like to add something to what Andy said about using ‘growth disorder’ as an excuse for remaining obese (not just overweight).

      I have been morbidly obese since I turned eleven and that was nearly fifty years ago. I was a normal weight child until the onset of puberty. Yes, I came from a family that had problems with obesity. Because of this we had (and still have) issues with portion control as it is currently called. They slimmed down. I’m the only one whos still has the weight issue. All my life I have tried to find an answer to why. I tried various diets, exercise, combinations and would always lose a modest amount of weight. I read enough nutrition books to qualify for a degree in the subject. Unfortunately I could maintain such losses for only a year or two. Invariably I would gain more. No one except another obese individual could understand the amount of frustration, self criticism and even hate that goes on inside.

      I understand that some people use any excuse as a reason not to try. I don’t consider myself ‘entitled’ to use any excuse. I try and try again. I look for answers. Do I get help from the medical community? Not really. I have had my share of condemnation for being obese from doctors, nurses. Have I run across a few who truly want to help? Yes and they are a godsend because they hear the hurt going on inside me. Do I eat too much? Soemtimes. Not enough? Sometimes. Do I eat a diet where I should be losing weight? Yes and it doesn’t happen unless I restrict my carbs to almost nothing. Is that doable? Yes and no.

      Would I like to be a normal sized person? YES. But I get frustrated and angry and hurt and to the outside world I appear to give up or want to be this way. I don’t want to be obese but it seems my physiology and hormonal structure are working against me. I haven’t given up. I don’t want to give up. But sometimes I need a little breathing room before I work at it again.

      Please before thinking that the person thinks ‘growth disorder’ is an excuse, think that maybe they are grasping at anything trying to make sense or give themselves some comfort in a socety that can be extraordinarily cruel to an obese person.

      • Donna, thanks so much for sharing your very important perspective with everyone.

  • Peter – one of your readers alerted me to the fact that you referred to my thermodynamics article in the comments section here. I did write something up on this – it is exceedingly simplistic and does not consider any of the detailed hormonal (mis)regulation that is likely the root cause of obesity. The simplicity of the article is largely due to the audience it was aimed at – folks who read my soccer website. Hopefully there is a little something in there that is useful, although I don’t think it really adds much to what you have written above. Anyway, I provide the link here in case anyone is still reading the comments section of your post. – Andrew


    • Thanks, Andrew. For those not familiar with Andrew, his work is really stellar stuff.

  • JohnK

    Just out in the NY Times – I guess we’re getting closer to the truth:

    Diabetes Study Ends Early With a Surprising Result
    Published: October 19, 2012

    A large federal study of whether diet and weight loss can prevent heart attacks and strokes in overweight and obese people with Type 2 diabetes has ended two years ahead of schedule because the intensive program did not help.

    “I was surprised,” said Rena Wing, the study’s chairwoman and a professor of psychiatry and human behavior at Brown University’s medical school.

    Like many, she had assumed diet and exercise would help, in part because short-term studies had found that those strategies lowered blood sugar levels, blood pressure and cholesterol levels.

    But, Dr. Wing added, “You do a study because you don’t know the answer.”

    Still, medical experts said there were many benefits to diet and exercise even if they did not reduce cardiovascular disease in people with diabetes.

    About 25 million Americans have Type 2 diabetes. Many are overweight or obese. On average, the disease increases heart disease risk by 2 to 2 ½ times, said Dr. Ronald Kahn, chief academic officer at the Joslin Diabetes Center in Boston.

    It seemed logical that diet and exercise would help reduce that risk. An earlier federal study found that an intense diet and exercise program helped prevent overweight or obese people with elevated blood sugar levels from crossing the line into diabetes. The hope was that a similar program could also protect people from heart disease.

    The study randomly assigned 5,145 overweight or obese people with Type 2 diabetes to either a rigorous diet and exercise regimen or to sessions in which they got general health information. The diet involved 1,200 to 1,500 calories a day for those weighing less than 250 pounds and 1,500 to 1,800 calories a day for those weighing more. The exercise program was at least 175 minutes a week of moderate exercise.

    But 11 years after the study began, researchers concluded it was futile to continue — the two groups had nearly identical rates of heart attacks, strokes and cardiovascular deaths.

    The investigators are analyzing their data and will be publishing them in research papers.

    But the outcome is clear, said Dr. David Nathan, a principal investigator and director of the Diabetes Center at Massachusetts General Hospital. “We have to have an adult conversation about this,” he said. “This was a negative result.”

    The study participants assigned to the intensive exercise and diet program did lose about 5 percent of their weight and managed to keep it off during the study. That was enough to reduce cardiovascular risk factors.

    “We showed that meaningful weight loss — let’s put ‘meaningful’ in quotes — could be established and maintained,” Dr. Nathan said. “To me that means we did a good experiment. We had a fair test of this hypothesis.”

    Some, like Dr. John Buse, director of the University of North Carolina’s diabetes center, said the study confirmed what they would have expected. Dr. Buse, a former president of the American Diabetes Association, said treatments including smoking cessation, statins to reduce cholesterol and blood pressure medications are so powerful that they could swamp the modest effects of weight loss or exercise on cardiovascular risk.

    Other medical experts said they were waiting for release of the detailed data collected by the researchers before interpreting the study.

    “It is hard to tell anything without the details of the study,” said Dr. Irl Hirsch, medical director of the Diabetes Care Center at the University of Washington.

    Dr. Nathan, though, said the results meant that people with diabetes might have a choice. The group assigned to diet and exercise ended up with about the same levels of cholesterol, blood pressure and blood sugar as those in the control group, but the dieters used fewer medications.

    “That may be the choice we are highlighting,” Dr. Nathan said. “You can take more medications — and more, I should say, expensive medications — or you can chose a lifestyle intervention and use fewer drugs and come to the same cardiovascular disease risk.”

    He is not going to say which is better, Dr. Nathan added. That is up to the individual. But, he said, “those are real choices.”

  • Ellen Urciola

    Hi Dr. Attia
    First, I just want to thank you for the long tireless hours you put into this blog. I know you would much rather be talking sports training , but I need some advice from you and your readers. I have been at 211 for nearly 30 days now consuming on average 20-30% protien and 60-65% percent fat and about 12-15% carbs. Just recently I tried upping my fat intake to 75% after noticing I had briefly dropped to 209 literally overnight at this consumption rate. The problem is I gained 4 pounds in four days! But my keto sticks show I am in ketosis (trace to small). I am so upset, literally at wits end. I struggled for 22months to find the right combination . At first I thought it was water gain because my ankle swells at night and I tend to gain 2-3 pounds during the day. All on less than 1000 calories a day, with no cravings or hunger pains. Is there some resource where I can find out about water retention. I am so upset, I feel like crying.

    • Ellen, I am very sorry to hear your struggles. As you can imagine, it’s really hard for me to try to diagnose the problem without spending a lot of time understanding everything. It might literally take me a few hours to even begin to understand what’s going on. Perhaps others can weigh in, but I’m so sorry that I can’t offer much at this time.

  • Ellen Urciola

    Hi Dr. Attia,
    I do want to thank you for your kind words. I was having a very bad day and I am afraid I took it out in my email.I panicked because I had just talked my doctor into cutting my BP medication and thought I was finally on my way! I have since regrouped and decided to go back to my original proportions.
    I know I am losing fat because my cloths continue to get baggy. I can fully understand what DONNA, in an earlier post, is going through. What I really want to know is if there have been any reliable studies done involving weight loss and water retention in women. Is water retention only a temporary condition? Are there any norms for how long water retention lasts? Does only fat loss cause water retention or are there certain foods that also cause it?
    I know if I keep reading your amazing blog that I will figure it out. After all, 17 pounds in three and one half months
    is pretty good. Thanks again. Ellen

    • Ellen, to put in perspective, for women to lose more than about 4 pounds per month is pretty remarkable, based on literature. So 17 pounds in ~14 weeks is really good!

  • Terry

    I enjoyed your podcast with Jimmy Moore yetserday on finding the right diet for your body. My question is regarding some adverse effects of a ketogenic diet containing less than 20 net carbs daily.

    I lost 40 pounds on a low calorie diet (from 2007 to 2009) then decided to find a diet to lower my pre-diabetic fasting blood sugar (fasting blood sugar of 98 to 110). I have been eating low carb (less than 40 net carbs daily) wheat/gluten/grain free for the past three years with weight maintenance. I am a 60 year old, 215 pound sedentary female and have been on a well formulated ketogenic diet (as described by Drs. Volek & Phinney’s Performance book) for the past 4 months in order to break my weight loss stall. Even on a diet composed of 1254 calories; 29 grams total carbs (9%); 68 grams protein (21%); 99 grams fat (70%), I have had no significant weight loss. Adding 30 minutes of daily exercise has not helped.

    I check my blood ketones twice daily and have had several episodes of facial flushing/chest pressure/tachycardia when my blood ketones are higher than 1.5. I have had a negative cardiac work-up (cardiac enzymes all normal)and a normal Stress test. Several other women have told me that they also experienced similar symptoms of such a “cortisol effect”. All of my lab results have been normal except for an elevated CRP (34.0).

    Is it possible that carb restriction below a specific level can trigger a cortisol response?

    • It is, but of course, the question is how do you interpret that cortisol response? Is it a normal adaptation or a pathological response? Same sort of question with TSH. So the challenge, in addition to figuring out which combination of macronutrients work best, is understanding the context of the changes in blood work.

  • Rosemary Tolentino

    You’re extremely inspirational. Is there a way I can personally contact you?

  • Hemming

    Hi Peter,

    I came across this study http://carlcam.co.kr/2006/ECS/sub05/pdf/9_10-10.pdf . I’m puzzled by figure 2 as I would have expected a line with a positive slope so that a greater reduction in serum insulin levels over the 6 weeks would have resulted in the greatest fat mass loss and change in body fat %. The authors also state “Inhibition of lipolysis occurs at relatively low concentrations of insulin with a half-maximal effect occurring at a concentration of 12 pmol  L-1 and a maximal effect at a concentration of about 200 to 300 pmol L-1.10 The significant reduction in insulin from 23.7 to 15.6 pmol  L-1 may have been permissive to mobilization of body fat on the carbohydrate-restricted diet.” Which seems contradictory to the figure.
    Am I misinterpreting the figure or what is going?

    Keep up all the good work you’re doing! Yuo have no idea how much it means to us, even those of us who struggle with the problem of underweight (especially after going low-carb and now ketosis).

    • Sorry, Hemming, I can’t see the figure you’re referencing.

    • Hemming
    • Hemming

      I would have expected that those who had the biggest drop in serum insulin also lost the most fat. But that doesn’t seem to be the case. For instance there is one who had a 50% drop in serum insulin but still gained ~0.5kg of fat.

      • These are pretty good correlations, actually, for a “biological system.” Doesn’t prove cause, of course (i.e., the reduction in serum insulin caused the loss in fat). To get at that you’d need to look at other experiments. But it does certainly support the role of insulin in regulating fat accumulation vs. lipolysis. There will always be outliers to every multifactorial biological hypothesis. Most overweight people also have elevated leptin…but not all of them. You get the idea. This is a good paper.

    • Hemming

      I still dont understand the slope of the line. As it is shown in fig. 2 it would indicate that a higher insulin level would induce the biggest loss of fat mass.

      • Isn’t it showing the greater the reduction in insulin, the greater the reduction in fat mass? That’s my read.

    • Hemming

      The text clearly suggests that hypothesis (which I would also have expected). But when I look at fig. 2, I still can’t can’t get my head around the axes. Those with the lowest decrease in insulin are showing the biggest fat loss. There is one who lost ~5kg of fat with an ~8% reduction in insulin level. Comparing that to the other one I mentioned it seems like insulin is a good thing for fat loss.
      I’m pretty sure this is a sign issue which is confusing me. Anyway, I just wanted to hear how you read the figure.

      Thank you.

      • Hemming, I went back and looked a second time. You were right (and, by extension, I was wrong!). I was puzzled by this, so I shot Jeff Volek an email. His response:

        “In this context the guys were young and normal weight and had relatively low insulin at the start and so even small changes translated into relatively large percent decreases. Going back to those original data it is clear that there is no correlation when the absolute change in insulin is plotted against fat loss.
        In contrast, in our studies with obese subjects, there is a significant correlation between decrease in insulin (pmol/L) and fat loss.”

    • Hemming

      Ok, thank you contacting Volek. Then it makes sense 🙂

      Given the curvature of the (in)famous insulin/lipolysis curve even small absolute changes can make a difference – at least just from looking at it in one of your other posts. I have no background in medicine though so I dont know how closely it generally fits the individual.

      In any case, mystery solved.

  • sharif

    Hi Peter, great work! my question for you is – In your opinion is it more important to be in a high level of nutritional ketosis (over 1.5mmol) Or, if one should be more concerned about keeping overall calorie intake low when trying to lose the last few kilos.
    I ask because I’ve been stuck at 18% body fat 6 months now so have decided to count calories (I noticed I’d been overconsuming calories) to achieve my goal of 10% body fat. While restricting calories, I do find it very hard to get my ketone levels over 1 mmol even while eating 70 – 80% fat, 15% protein and 5% carbs.
    Would you recommend increasing fat to get into higher levels of ketosis or to disregard ketone levels and concentrate more on restricting calories?

    • I’ll address this in the remainder of the ketosis series.

  • Hemming

    Hi again Peter,

    Sorry for bringing up all these studies but I think this one http://ajcn.nutrition.org/content/26/2/197.full.pdf is more interesting than the first one (perhaps you’re already familiar with it).
    It shows that even an intake of 600g fat/day did not induce weight gain. That is interesting in itself. What I was more surprised to see was that the correlation between fat intake and weight gain was less pronounced for corn oil than olive oil. The researchers contribute this to the higher LA content in corn oil. Do you have an explanation for this as I would have thought that reducing omega-6 would be more beneficial? Could it be because corn oil (per g) is higher in essential fatty acids?

    • This was one of the 84 studies or so we reviewed at NuSI (http://nusi.org/the-science/review-of-the-literature/#.UOBlKm9Pyg4). Main takeaway is that the study was too poorly done and reported to draw much conclusion.

    • Hemming

      Interesting. I had not seen that list before, its very useful to have as a reference when going through papers. Will it continuously be expanded?

      I do think that the idea of the study is interesting as I’ve seen other n=1 experiments which also consisted of a very high fat intakes that did not result in weight gains.

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  • Hi, Dr. Attia

    Most people who promote calorie counting don’t realize that :

    Calorie labels are wildly and enormously inaccurate. This is to the tune of 10 % to as much as 80 % off as Dr. Jeffrey Friedman points out.

    And even if there were accurate nobody could consciously match expenditure to intake with the many millions we consume over a decade. Calore counting is a completely false illusion.

    Take care,


  • Jeff Johnson

    Dear Raz –

    1. Wrong – “Calorie labels are wildly and enormously inaccurate. This is to the tune of 10 % to as much as 80 % off as Dr. Jeffrey Friedman points out”

    You expect me to believe this crap ? To indulge yourself in some insane form of anti-calorie counting is interesting only in the aspect of how one idiot sheep is more than willing to follow a leader idiot sheep –

    Frankly – I’m tired of this nonsense being parroted as it causes a gret deal of harm – it hurts people – it solves nothing –

    2. Anyone – can test this for themselves – eat as much fat as you like – stay in ketosis – and watch the pounds melt away –

    What F————- nonsense – it’s a game you can’t win – if those fat calories equal or exceed your bodies needs

    • Jeff, maybe I’m wrong, but I though Raz was making the point that calorie labels may be far enough from accurate measurements, that even if you wanted to could them this way, it might be tough to balance.

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  • Joseph

    Hi Dr. Attia,
    Your blog and research is brilliant combination of scientific evidence and anecdotal support, and your journey toward health, heretical as it is, is inspiring. Thank you.
    I believe you noted in one of your lectures that after taking on the first few step of a low-carb diet, you tested insulin response to glucose and found that it was a much more modest insulin response than on your previous high-carb diet. Very interesting. A question regarding insulin sensitivity: I’ve heard that that long-term exposure of cells to ketones retard insulin-induced activation of the insulin surface receptor, thereby making a ketogenic dieter more sensitive to carbs once added back into the diet. What’s your take on this, Dr. Attia? Thank you

    • Very good question, and one we don’t know the answer to. “IR” is a broad term. Do we mean liver, brain, muscle, fat cell? All have different responses, but crude measures like HOMA-IR just average them all together.

  • Elyse

    Hi Dr. Attia,

    I have struggled with my weight my entire life. I lost about 50 pounds in 2012 and have kept it off now for about 9 months (with about a 5 pound swing). I also started weight training in 2012 and have significantly increased my lean mass (in addition to the significant fat loss). The weight loss is attributable principally to significant carb reduction (although I still eat about 100 grams of carbs a day- mostly vegetables, occaisional berries, and carbs from dairy and nuts- I have cut all grains and legumes from my diet) and to “Leangains” style intermittent fasting. I weight train 3 times a week and do indoor cycling (spinning or computraining) once a week. I have not done a DEXA scan, but based on caliper testing my body fat is now at about 21%. I would like to get a little leaner and have tried reducing carbs further but I find that I am ravenously hungry when I limit carbs to below 50 grams and proteing to 150 grams- somehow I can’t seem to fill up enough on fat without hitting insane calorie intake (upwards of 4000 calories). When I eat to satisfy my appettite I end up gaining weight (because I end up eating loads of cheese and high fat meats). I have put tremendous effort into being mindful about when I am truly hungry (eating slowly, paying close attention to hunger cues, etc) and honestly believe that I am only eating when I am hungry (and not eating emotionally, solely for pleasure, or for sport). Are there some people who simply cannot rely on appetite as their cue for how many calories to consume? If so, what could account for this and are there any solutions that you can offer? Many thanks.

  • Jessica

    I’ve been trying to navigate through your blogs to find this answer, so I apologize for these possibly dumb questions:

    1. Is there a continuum of benefits (of any kind: insulin sensitivity, weight loss, trig reduction, etc) seen from a continuum of CHO reduction?

    2. Does the source of CHO matter? I saw your graphs from your ‘personal journey’ blog (how you gradually reduced CHO and your bloodwork associated with each stage). But while I’m getting that you say a calorie is NOT a calorie, is a carb NOT a carb? Or is a carb is a carb is a carb?

    3. I also saw a response in one of your question and answer sections: Q:”Is ketosis for everyone?”. And you said something like “definitely not”. How does one know if they should try it? It seems like quite a challenge for most people.

    Thanks for your work on these topics.

    • Perry

      Hopefully Peter will jump in with his thoughts. Here are some of mine: First, remember that individuals vary a great deal.
      1.I don’t see a ‘continuum’ of benefit from reduced carbs, but more like ‘steps/stages’ which can provide benefit. For example, cutting out sugar; cutting out grains and other starchy foods ( low carb); ketogenic (very low carb).

      2.If the person has any signs of insulin resistance/ carb intolerance/ blood sugar fluctuations, then I think the source of carbs matters (as well as the quantity). Rapidly absorbed carbs (sugar/ corn syrup, etc) have a negative impact compared to the carbs in something like broccoli/cauliflower/cabbage.

      3. For many people getting into and staying in ketosis is harder than low carb; so whether you should try it really depends on your personal situation…what do you want to improve? Do the benefits that people report match your goals?

      I’ve been doing low carb for almost two years. I started out gradually, using “Life Without Bread” as my initial guide. I did a lot of reading. I gradually moved my carb count down; using “The New Atkins for a new You” , “The Art and Science of Low Carbohydrate Living”, and “Primal Body Primal Mind” as guides.

      I’ve lost 60#, going from 230# to 170#, and have observed a number of health benefits.

      I’ve tried and gotten into ketosis (barely) twice before now; blood ketones generally in the 0.5 to 1.0 range, but occasionally dropping below 0.5. The first time I stopped because I like to do multi-day hiking/pack trips. I had not figured out how to stay ketogenic using dehydrated foods. The second time was traveling and again having trouble with not having the right foods on hand.

      I don’t have it all figured out yet, but I’m finding that I need to not only eat very low carb, < 20 grams of net carbs, but also moderate protein, < about 80 grams, with only a small part of that coming from dairy protein, and not too much of the daily protein allotment at any one meal.

      I’ve been on a ketogenic diet again the last two weeks. I’m having more success this time…primarily by getting my fat intake up. This has moderated my appetite, so it’s fairly easy to keep the protein down. What I’ve changed about my fat intake is adding a cup, or two, of ‘fat’ coffee/decaf a day (with a generous amount of coconut oil & heavy cream). I’m also putting more butter on vegetables, pouring the ‘drippings’ from cooking meat, over the meat when I serve it, and things like that.

      In comments under Dr Attia’s blog “Ketosis – advantaged or misunderstood state? (Part I)”, there was a comment about using a ketogenic adjunct such as coconut oil, MCT oil, or AAKG (Arginine alphaketoglutarate). I had not heard of AAGK before…so googled it. There’s not a lot of info available…much of it is related to AAKG being sold as a supplement for strength training and fitness. I found enough bits & pieces to decide to buy some AAKG and give it a try. I’ve been using it in a ‘keto broth’…broth with coconut oil, heavy cream, and 1 scoop (2 grams) of AAKG. I’ve been drinking it 3 times a day. To me, it has a somewhat tangy/ lemony flavor…I like it. It seems to boost my ketones 0.5 to 1.0 above what they would otherwise be. I think this has also helped me get into ketosis…with ketone readings in the 2.0 to 2.5 range, where 1.0 was as high as I’d gotten before.

      It has been a challenge, but for me it’s been worth it. I’m sleeping better, and have noticeably more energy. And, the minimal hunger has made it relatively easy to stay with the diet, once I figured out what to eat/drink.

  • Joseph

    Is carb resistance the same as inulin resistance?

    • No, but they are related. IR is a very complex state and involves many organs. One can have IR at the levels of different cells (liver, fat, muscle, neuron).

  • Joseph

    Do you use carb resistance and insulin resistance interchangeably? People who insulin sensitive aren’t prone to weight gain, but I saw in a comment that you said that someone who couldn’t gain weight was carb resistant. Is it that people who are deemed insulin sensitive are actually insulin sensitive on their muscles cells but not their fat cells?

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  • Razwell

    Hi Dr. Attia

    I fully support you and your efforts. I wanted to tell you that most poeple are applying a closed system equilibrium thermodynamic approach to humans . I have spoken to some of the very best biophysics professors from Oxford, Caltech and Cambridge and what they told me is this:

    *The human body is an open system

    *The human body is a non- equilibrium system
    And because of these two facts, this makes the situation hellishly complex to the maximum. If we could evben come up with some equation- it would not be singular. It would be many equations. None of the scientists I talked to could even give me a rough idea of what this might look like and admitted as much. These are top minds too.

    We have to consider free energy ( which includes entropy) rather than energy. This area of thermodynamics is extremely subtle.

    Nobody mentions the sun either. or skin temperature, or the fact we excrete energy.

    I have it on top authority that fat and muscle gain and loss have to do with extremely complex physiological and biochemical processes- it’s not a basic thermodynamics problem. These were the words of the scientists.

    Best Wishes,


    • Thanks, Raz. All of these can be measured in sum (though not necessarily in isolation), via indirect calorimetery or even doubly labeled water. So I don’t disagree with your point, but it doesn’t change my argument. My point is that something other than *only* caloric balance can drive fat accumulation, *and* this does not violate the First Law. I could not agree more that the First Law is a meaningless way to think about physiology. It’s obvious, and it adds no value.

  • Peter –

    You said: “Similarly, genetically identical twins can eat different macronutrient diets (i.e., differing amounts of fat, protein, carbohydrates) of the same number of calories, while doing a constant amount of exercise, and accumulate different amounts of fat.”

    Are you speculating here or are there controlled studies that support this?

    • I don’t think this exact experiment has been done, though slightly less interesting variants have. It would be a very elegant experiment, and we have discussed it in great detail.

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  • JLMA


    I have been following the VERY low-carb approach for a while now. I feel good, the circumference of my waist definitely went down and my blood markers are excellent.

    My question; although my fat deposits appear to have gone down a lot, I still have fat around my abdomen that I’d like to lose.

    My nutrition is mostly ONLY FAT and PROTEIN (except for some sauerkraut here and there). Reading your blog I realize my problem may be I am intaking TOO MUCH PROTEIN.

    I wonder if I may also be intaking TO MUCH FAT, and thus my body is not burning abdomen fat?

    In order TO BE LEANER while on a FAT-&-PROTEIN-ONLY diet, how does one know if it is PROTEIN ONLY or FAT ONLY (and by HOW MUCH) that needs to be cut out?

    I guess I mean, WHEN IT COMES TO BEING LEAN, is it not only a matter of LOW CARB BUT ALSO CONTROLLED CALORIES (meaning does the amount of calories matter when it comes to being lean)?

    Thanks a lot for a lot for the effort to share the information in this blog.

  • JLMA

    I continued to think about my previous question and I realized I need to split my question into two (related) ones:
    (1) what are the PROPORTIONS or MAX AMOUNTS of FAT and PROT that will allow me to BECOME lean?
    (2) what are the PROPORTIONS or MAX AMOUNTS of FAT and PROT that will allow me to STAY lean?

    I understand this probably are different from person to person (based on gender, age, level and type of activity, etc), but is there a rule-of-thumb kind of guidelines I could start off with?

    I already follow a very low carb diet but still not lean as I’d like (still abdomen fat deposits), so I assume my PROPORTIONS and/or AMOUNTS of FAT and PROT are what I need to adjust. Any guidelines to follow?


    • Adam

      I can tell you from my experience, after losing weight in ketosis, I also had another 5-10 lbs I wanted to lose. A few strategies that helped me:
      1.) 2, 24 hour periods of intermittent fasting per week combined with training in my MAF zone ( see Maffetone Method http://www.philmaffetone.com/whatisthemaffetonemethod.cfm ).

      2.) Replacing some of my high dairy or moderate protein meals with “bulletproof” coffee ( strong expresso, 2 tbsp coconut oil and 2 tbsp grass fed butter in a blender ). This stuff is amazing, delicious and satiates for very long periods of time.

      3.) Saving most of daily carb intake for right after my high intensity anaerobic workouts.

      I was able to lose a significant amount of stubborn abdomen fat with this so far.


  • JLMA


    Thank you for your input. Help me start implementing your input by letting me know how these three tips rank in burning-stubborn-fat-effectiveness (which one is the best of the three tips? second?).

    Once you reach your goal, do you plan on quitting these strategies?

    Where do I find good coconut oil?

    Thanks again,

    • Adam

      Although I don’t have any blood testing gear to measure precisely, I think for me, the combination of replacing some dairy and protein with more fat made the biggest difference. I kind of did these 2 at the same time so I can’t rank one over the other.

      I have more recently cut back on the fasting because I started cycling to work. That combined with my lunch time workouts left me pretty obliterated while trying to fast. I’m not saying it’s not possible to adapt to this as Dr. Attia has attested to with long bike rides, but I haven’t worked up to that yet and currently don’t plan to. If I have an easy workout or rest day, I might still fast until dinner.

      I used to get my coconut oil from Trader Joe’s until my wife started liking it. She now cooks with all the time, and we started running out quick. So I actually found some at Costco that comes in 3 quart buckets. The brand is Nutiva, and it’s organic as well. -Adam

  • JLMA

    I am new to coconut oil. I have always (only) used extra-virgin olive oil. Would you say these two oils are interchangeable? Would one be a better choice than the other when the recipe calls for raw oil? and when the recipe involves heating the oil up?

    (I thought that by entering my email I’d be getting comment updates, but I am not)

    • Healthygal

      I am new to coconut oil also. I understand it’s best used for cooking, since it will not burn at higher temps. like olive oil would. I’ve been using it for baking and stove top cooking, but still use olive oil for salad dressings and sauces (low temp. cooking).

  • A.C. Rubey

    Hi, Peter. Thanks for such detailed information. I have a question — how do you square what you are saying with the assertions of the Calorie Restriction folks and the studies by Dr. Roy Walford (and others) who put the focus on eating a primarily vegetable diet (the only way to their way of thinking that you can get your calories low enough to contribute to life extension). I really can’t reconcile what Walford/ Ornish/ Barnard etc. are saying with what you and Gary have contributed (I talk about my struggle some in my new blog: http://foodchoicecity.blogspot.com/). Lots of folks with good credentials/intentions with wildly differing opinions. Yikes!

    Can you help me understand this? The more books I read, the more my head spins. I really don’t know what to eat anymore.

  • Desiree

    Hi Peter, thanks for a great website. I’m new to low carb eating and have one question. Do I still need to eat during workouts? I’m a cyclist and I do rides of about 2-4 hours 3 times per week. I rode for 2 hours the other day and felt fine with just water, but my husband is concerned that I’ll pass out or something. I should mention that I’m trying to lose weight (and at 27% fat I think my body should burn it’s own fat for energy) I read that you take cream and nuts during training, but I don’t train anywhere as much as you. What do you think?

    • See posts on interplay of exercise and ketosis. I can’t really know if you need to eat, but hopefully these posts will help you think about it in your case.

  • Hemming

    Hi Peter,

    I came across this BBC documentary http://news.bbc.co.uk/2/hi/uk_news/magazine/7838668.stm (the show can be streamed here http://www.dr.dk/tv/program/hvorfor-er-tynde-mennesker-ikke-fede on a Danish site for free). The idea is that a group of people overeat for one month on crappy food and gain weight. The interesting is then that they, more or less, lose all of it again in one month without any special effort but just by living like they use to. The conclusion is that we all have a genetic weight set point. They only tested weight, body fat and measurements and not how the diet affected blood markers etc. They also do an experiment to show that some people are genetically disposed to eat even though they feel full.

    For what it’s worth, I wanted to share the documentary.

    Good luck on your current work.


    • Thanks, Hemming. The question I have from this is what accounts for the average rise and individual rise in the majority of people?

    • Hemming

      Do you mean in terms of it’s the calories or the food choices? Or whether which factor (be it gene, activity level etc.) that affected their weight gain the most? I would also have liked to see the macronutrient breakdown of the diet. What I found particularly interesting is how some people ‘can’t’ overeat. This is also something I’ve noticed with myself in that I find it easier to eat less than more – something that made it very easy for me to lose too much weight and currently really difficult to gain anything.

      I agree that there are a lot of open questions to this experiment. I assume BBC just paid for it to make a show and not a scientific study.

      • I don’t agree with the notion (or, more specifically, the implication) that there has been a genetic shift in our set point to be more obese. Certainly a set point plays a role, but I’m not sure it’s pre-determined. I’m guessing it’s more epigenetic than genetic, when it comes to movement.

  • arris

    good morning doctor i would like to know how to stop diarrhea in a high fat diet.
    iam 6foot for 250bl how much fat to i need. iam struggling with those 2question if you can please help thank you

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  • Alison

    I just discovered your site today, and have spent many hours reading through posts and comments. So much great material!

    I would like to ask … what about those of us who do not get into ketosis? In my case, I get fasting (even 12hr+) BG results of, say, 400. Current HbA1c = 11.1%. Have had raging diabetes, not just IR, since age 35 (21 years), and under today’s standards probably would have been warned between the ages of 17-21. Multi-century history of this type of thing on the side of the family I resemble. My diet is carb-limited (no rice, pasta, bread, soda, added sugar, other junkfood) but not truly low-carb at the moment. Reading your site may inspire me to try yet again.

    Metabolic complications include iodine hypersensitivity and low body temperature, with reverse fevers. Have failed on all diabetes drugs (severe side effects), and current ~30 units/day of Levemir doesn’t seem to do anything. I’m terrified of increasing the dose and just gaining more weight, staying on the same hamster wheel. I realize you can only make general statements here, but have you seen results absent ketosis?

    • In short, yes. I understand your concern, though, and I’m glad you’re considering a dietary change.

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  • Rebecca Hernández

    Dr. Attia, thank you so much for this website. I sent an email through NUSI, but I’ll post here as well.

    I am an RD from Costa Rica, I found your site after listening to your TED talk.

    First congratulations, and thank you for making the infomation so accesible. As I understood insulin’s role in biochemistry , I questioned the “conventional dietary advice” they were telling me to give. Good thing I have learned not to apply it!

    I want to share this blog with my patients, and request permission to share the key concepts you point out in Spanish, all cited obviously. I think it will be of great value, specially this article since a lot patients insist on counting calories!

    Thank you !

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  • Jim Keen

    Hi Peter! I’ve been reading this blog since you started it and have deep gratitude for your willingness to share all of this with us free of charge. Generous doesn’t even begin to describe it, and although it’s a “labor of love,” that still means there’s lots of labor involved! So thank you.

    Dig this quick bit of housekeeping (and I only bring this up because your pristine writing tells me that you place a high value on this sort of thing): Under “Key Concept #3- Current Dogma,” you write:

    “…but the possibility remains that another factor led to you to overeat.” I think there might be an extra “to” in there. Maybe it should read, “…that another factor led to your overeating” or “…that another factor led you to overeat.”

    Super trivial, but I hate when I make little typos on my own blog and I love it when people let me know about it.

    Again, thanks so much for your work. You have maintained a standard of quality in your writing, your public speeches, and your demeanor in interviews that lends some much-needed legitimacy and professionalism to this movement.

    • Thanks Jim. I’ll try to remember and fix.

  • Christian

    Hi Peter,

    first of all awesome website I have to say… Quite interested in the nutrition stuff because all my doctors are still on quite the old dogma to eat about 60% carbs and “JUST” reduce the kcl intake. Which I do about 5 years and nothing is happening… Enough said 😉

    I just started about one and a half week ago with Atkins phase 1 and it is working quite well for me right now (lost 5 kg)… What I am still unsure of is, how much kcl I should intake? With “help” of the doctors I just comsumed about 1800kcl per day. So my metabolism might me quite down :/

    With 3 different calorie/bmi calculators I came up with ~2200kcl basal metabolism and ~2900kcl total turnover. And I am sticking with about ~2500kcl.
    Do I need to adjust this? Cause I am already hitting a plateau :/
    What did you consume/count!?!?

    Thanks a lot!

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  • Kenneth Chiu

    Ultimately, it seems that you are saying that what we eat affects our hunger/appetite, and that in turn affects how much we eat. Is this a reasonable summary?

    Also, could you clarify a little what you referring to when you write “Conventional Dogma”? Do you mean the scientific consensus, or something else?

    • Correct. And by conventional wisdom or dogma I mean the adage that fat balance is DETERMINED by the number of calories ingested (rather than, say, the number of calories ingested is determined by something else, such as hormones and enzymes in our body that regulate fuel partitioning).

  • Kenneth Chiu

    So as someone not in the field (my field is computer science), it doesn’t seem surprising to me that hunger/appetite is affected by diet composition. In fact, the exact opposite, that diet composition had NO effect on hunger/appetite, would actually seem to be more surprising.

    I’m somewhat surprised (or perhaps “dismayed” is the more accurate word) that the science has not been settled on this decades ago. One study that might be interesting would be to simply put one group of people (who were trying to lose weight) on a high-fat diet, the other group on a high-carb diet, and let them eat as they wished. The tricky part would be how to maintain the diet composition without imposing any other restrictions that might bias the results. (Or maybe such a study has been done?)

    As an aside, I’ve found your personal site to be quite informative. I’ve recently been trying to go from 145 to 130 lbs., and have been looking for a site that provided in-depth analysis of the science. On a personal note, I’m currently collaborating on a project looking for epistatic effects between the mitochondrial genome and the nuclear genome in yeast. I wouldn’t be surprised if somewhere down the road we discover that epistatic (and epigenetic) interactions between the mitochondrial DNA and the nuclear DNA are in part responsible for obesity.

    • Kenneth, I hear you. Perhaps my math/engineering background is why I’ve come to the same conclusion over time.

  • tosha

    I was thinking about this as an idea, “Is it possible to hack your body to burn fat, while feasting on low carb whole foods”? I decided to take the idea of the bulletproof diet, and the idea of keto that allows me to think of making a combined plan, Not totally paleo(bulletproof diet) because It would still rely on a lower amount of carbs like 20 or less, and include diary fat, and no refeeding. I was thinking about this from one person that told me about a plate, If your plate is 80%+ fat and rest is from protein and few carbs like less then 9grams an hour but as long as your eating a huge amount of fat you will never have the possibility of that food to ever turn to fat on the body. Almost like a soldier defending your body from getting fat. Then I was thinking about how true it is that if your body is eating a lot of food, which some make it seem hard to do. but oddly I find fat not filling so I can eat alot.. Any ways, I mean like enough over 2000 or more that your body will never be in starvation mode and begin to drop those fat pounds cause it wouldn’t have to think about holding on to anything your eating since your never in starvation mode. Your body will be thinking.. I guess I am being fed I’ll always have energy so I can keep working and not hold on to anything new that comes in from the mouth. Then your body will be using all the food and excess from your body as well, while perserving the muscles from the protein intake being enough to keep and maintain them. which will also lead to weight loss.

    I was wondering with your thoughts… if you had any thoughts to the idea if your body is running on unlimited amounts of fats, from 75-90% like would they really be able to lose a way lot more easier then eating a typical low carb plan?

    I knew of the guy who did the 5000 or so calories a day and was put on youtube
    he did a high fat low carb plan for 21 days ended up only gaining only think like barely nothing when he should gained a load of weight… but instead he only gained a few pounds like 3 i think or something and lost inches

    which was a surprise then he recently did 5000 and was eating all carbs and junky foods. each day in 21 days he gained 15lbs i think it was and got heavier around the waist

    So in some way I was wondering if you might have any idea if its true, that one person to eat a load of fat.. ( no calorie restriction) keeping metabolism high and never running out of energy or thinking about starving. that you won’t ever gain and maybe allow a chance the body to adjust that you begin to lose the weight you need cause your body will be more energized and using all the fat on and what your put in your body, without thinking about saving any… Do you think is this a possible thought?

    thank you

    • tosha

      I ment to put for a female very much low in the weight department, been testing the idea and ahve been at 2600-3000 calories a day.. and been pretty good .

      from 1600-1700 was able to lose 2 lbs in 3 days then moved up to 2000-2200 and soon lost another pound
      so now eating 2600-3000 and no weight loss yet but only been well today is day 9 so in a week lost 3 lbs and starting week two.

      I just found it hard that i’m oddly hungrier during the day cause i’m eating a lot less food even tho i eat 5 times a day every 3hours. but I notice my appetite is high cause fat don’t really fill me,

      so my other question I ment to ask is, Do I keep my protein the same and just add in loads more fat.

      a typical meal is like half an avocado,( have usually with every meal) and tblspoon grass fed butter with either if pork loin boneless pastured 4oz size or a fattier amount of meat with grass fed beef 85% lean

      doesn’t keep me full for long, but tastes good tho if i could i’d love to have more but wasn’t sure how to approach it. I do want to see if more = will boost weight loss or even cause maintain since at a no need to lose, at a low weight allready.. or if its a bad idea, to go pass the ( old saying 3500 calories= 1lb) when typically its what your eating..

      what do you think?

      sorry for so much questions.

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  • Crystal

    Hi Peter. Thanks for the great site. I have been on a ketogenic diet for 5 months and I have lost 70 lbs (although I have about 140 more to go – I started at 345 lb). When I first started, I was eating around 1800 calories a day, with the number of daily calories steadily declining to where I now struggle to eat 1000 calories per day and some days 800. Throughout, no matter the number of calories I consume, I always end up with a macro ratio of 65-70% fat, 25-30% protein, and 2-5% carbs. My concern right now is that I am not eating enough calories, although I do manage to keep my protein to within 70-90 g. Since I am in ketosis, where I have access to my own body fat to burn for fuel, do I need to worry about eating a certain number of calories (i.e. at least 1200) to keep my metabolism ticking along, or does this only apply to carb-burners? Do I need to try to force myself to eat more, or just eat when I am hungry (in which case I will probably eat around 1000 cals)? Who knew that not eating enough and rarely being hungry would ever be a “problem” that I would have to worry about 🙂

    • Crystal, as crazy as this sounds, you are eating more than you know. If you’ve lost 70 pounds in 5 months, and assuming about 10 pounds of that was water, it means you’re averaging about 180 gm/day of fat loss (net). This is much more than most. Average is about 65 gm/day and up to about 130 gm/day. What this means, of course, is that your body is “eating” itself to the tune of about 1,600 kcal/day. So with your intake at 1,000 kcal/day, this suggests your body is requiring about 2,600 kcal/day per day: 1,000 from what you eat, and 1,600 from your own fat stores.

  • Maia

    Hi Peter,

    First, I think this post and your blog are absolutely brilliant. I’ve read some of Gary Taubes’ work as well, and it totally rocked my world.

    Anyway, I was wondering if you could help me work out a little mystery.

    I am 24 years old, female, 5′ 4” and for most of my teenage/adult life, I tended to be chubby. I never ‘exercised’ exactly (though I wasn’t totally sedentary either– I would walk to classes and around town w/ friends, etc) and I ate whatever I felt like, which included a lot of fast food, junk, and carbs. My weight pretty much stuck between 130-145. Once, it even went all the way up to 158 (perhaps due to a change in medications).

    About two and half years ago, I got sick of feeling chubby, and finally, for the first time, tried to seriously diet. I did the south beach thing, and started working out, doing about an hour of yoga a day and speed walking for 30 minutes. I was eating around 1500 calories, and I lost a ton of weight. It all sort of spiraled into what I recognize now as an eating disorder (I was going through a lot of other emotional issues at the time). I was down to 106 pounds, calorie counting obsessively, and had intense anxiety over food and exercise. Eventually I realized I was no longer well, and tried to pull myself together and eat normally again. Luckily, because I had never suffered from these issues before, and because I had a supportive fiance, I was able to ‘snap out of it.’ It took a while for my anxieties to disappear, but I was able to start eating normally (probably even over-eating) relatively easily, because my body had been hungry for so long, I was craving food anyway.

    That brings us to today. For a year or so, I have been consciously, purposefully eating as much as I want of whatever I want– which is to say, probably poorly. I am back to eating sweets and carbs– which have always been my weakness. I am, perhaps, a little more active than I used to be, but I am back to exercising infrequently– sometimes I will go weeks without doing anything more strenuous than just walking around. And the calorie-counter in me KNOWS that I must be consistently eating more than I expend– I counted calories neurotically for a year, so I can’t help but have a pretty good idea of how many calories I eat, even when I try not to think about it. And many of those calories are carbs.

    And yet, (and here is the mystery), I have stabilized at about 115 pounds. It has been over a year now of near-inactivity and eating junk, and my weight has not fluctuated at all. A base weight of 115 is way thinner than I ever used to be, when I was eating the same number of calories, eating the same carbs, at the same general activity level. So what’s the deal here? The science doesn’t seem to add up– whether you subscribe to the calories in=calories out OR the carbs vs low carbs theories.

    Did my eating disorder somehow reset my metabolism (instead of messing it up like everyone warned it would)? Must I just be hallucinating and eating less/excising more than I realize? Did I fix my bodies response to carbs? Does it have to do with getting older?

    I’d be interested to hear any theory you might have– I have been really perplexed for a while!

    • Maia, there is so much I’d like to say (and speculate) about this, but I don’t know how to do so in short order. I will say this, at some point I will definitely address this in the context the relationship between obesity and anorexia (I’m not saying you have the latter, but you’ll understand why I’m making this point when I get to it). The issue is one of too much or too little fat storage vs. what most would say is a behavioral issue.

    • Donna

      I know you are an extremely busy man with so many topics you want to explore but I would be very interested on your take on obesity and anorexia versus behavioral issues. I’ve come to the conclusion that chemistry, biology , physiology trumps behavioral this time. I’ve gone the behavioral therapy route and it is not a solution or fix.
      Of course try to explain that to the current believers in that and well.it doesn’t get one very far or gets one any real help.

      • I definitely look forward to addressing this. I believe anorexia may be as misunderstood as obesity.

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  • MsMaar

    Hi Peter!
    Love your blog! Got a question, is there a minimal daily caloric intake an individual (lets take me for example 5ft7, 68kg girl, 20yrs old) has to meet to reach ketosis? The reason I’m asking this is because I often find it hard to get in more than 1500kcals a day and I had underactive thyroid issues in the past on a vegan diet and the last thing i wanna do here is to put my body in a starvation mode again which is what you do when not eating enough.However I find keto diet to be very satiating and often forget to eat and when I do I eat less (smaller meals that is) however I do keep it at 3 meals a day to boost my caloric intake…My macros are 70 to 80 percent fat, around 20 percent protein and less than 10 percent carbs…Moderate activity level, 30 to 45 min workout daily or every second day (mostly squats, lunges, leg raises, kb swings, etc)…So to make long story short is it only about getting the right macros or there is a calorie minimum one should satisfy to enter ketosis in first place? Also in that case how to differentiate keto adaptation weakness and fatigue from being too low in calories, any advice would be much appreciated! Much love!
    MsMaar 🙂

    • No, in fact the fewer calories (e.g., starvation), the easier it typically is.

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  • Phil

    Hi Peter,

    I first saw you on a very emotional video about metabolic syndrome – I’m sure you know the one. Very inspirational stuff, loved it!

    Anyhow, bit of a nerdy question for you here…

    I can see you are an advocate of the ketogenic method to body fat reduction…had you ever tried using a diet primarily made up of carbohydrates (small amounts) to use a pre-curser for gluconeogensis (& lipolysis) via the krebs/citric acid cycle as glucose—>pyruvic acid —>(fatty acids)—> Acetyl co-a —> ATP?

    An alternative method which although supported by our biochemistry – is rarely seen practiced to my knowledge. Wondered if you had tried to reduce body fat consciously this way??


    • Phil, for pyruvate to go to acetyl CoA to FA, requires a lot of carbohydrate. This is called de novo lipogenesis. See the post on fat flux for a greater explanation.

    • Phil

      Thanks for the reply Peter.

      As I understand, carbohydrate will not really suffer lipogenesis unless glycogen levels are at the maximum level right? And as far as there is glycolysis available, gluconeogenesis isn’t needed as a route to ATP, hence the key in the method above would be keeping glycogen levels very low – just enough to provode the pre curser for fat to enter the krebs cycle.

      It’s a good discussion point for me – I used the method above to go from 28% to 10% in 5months wothout exercise and my diet consisted of 80% carbohydrate (most kinds), very little fat & very little protein. Essentially, the opposite of what you did for your transformation.

  • Vicente

    Hi Peter,
    I am a 42 years old guy from Spain that has lost 55lbs in the last year. Moreover I feel better than ever (specially about my former NAFLD, high iron levels and hiatus hernia). I owe that to you and to Gary Taubes, because it were your videos on youtube what really helped me a few months ago.

    Today I created a small document trying to put some of the ideas from your article in a more visual form. I am an engineer so please forgive any mistake in the document. I just wanted to test if it was a good idea to explain things more visually. I hope you like it.


    Your sincerely,

  • Vicente

    Let’s say I have a business: I sell only one model of car and the benefits I get every year can
    be calculated as:


    where N are the number of cars I sell in a year, P is the selling price of one car,
    C is their unitary cost and E are my other expenses. If I ask a nutritionist how can I earn more money he/she could say “to earn more money you have to earn more money”. True, isn’t it? But useless, so I ask another one and he/she says:

    “It’s very simple, you have to:
    1) Raise the price of the cars
    2) Sell more of them”

    So, isn’t it true that you will earn more money if you sell more cars at a higher price?
    Of course it is. Who can deny that?

    But the questions are, a) can you really do that and b) do it without changing other terms of the equation,
    short term or in the long run?

    Can you really raise the price without reducing your sells?
    Are you really going to sell more cars just because you have decided to? Even if you achieve to sell more
    cars at a higher price, is it sustainable? How will your expenses change if you sell more cars? (can you sell
    more without increasing the staff?) The answer is simple: an equation doesn’t give you the clues
    to have a succesful business. You need to understand how the market works.

    “Eat less and exercise more” is as useless as “sell more at a higher price”.

    • Very nice analogy, Vicente.

      • Barry Fisher

        Yea…nice, clean, concise, simple. We Keto-Gypsies need stuff like that. I’m just enjoying reading these posts. Swift.

  • Vicente

    Hi Peter,
    you wrote elsewhere in the blog that explanations on this topic are much longer than the “calories in, calories out” falacy. As you said, that is a handicap when trying to explain things.

    I believe the following counterexample may be interesting:

    For 3 weeks a guy eats 5700 Cals/day mainly FAT and his weight goes up 1Kg. His CVD risk factors get better.
    For another 3 weeks the same guy eats 5700 Cals/day mainly CARBS and his weight goes up 7Kg. His CVD risk factors get worse.
    How can the weight gain be completely different if he eats the same Cals/day in both experiments? How can it all be about the total calories you eat? Are all calories the same when talking about health if certain kinds of food make you sick and others don’t?

    NOTE: This is not a thought experiment. The guy’s name is Sam Feltham and here you can find a complete report

    • I’m aware of Seth. I can’t speak to the accuracy of his calorie counting, “ins” and “outs,” etc. My point is that glycerol shortage may not be the reason L>R-E (see nomenclature from fat flux post), which is is the necessary condition to enable this.

  • Vicente

    Hi Peter,
    you are right. It is a wise stance not to trust data unless there is a minimum warranty. That could be a false step.
    I just liked the idea that it was simple to refute the “a calorie is a calorie” idea without too long explanations.

    Apart from that, even if you in the future decided to stop publishing in your blog, you should know that what you already have done has been really important at least for me. You have provided a lot of people with the information needed to change our diets. When I told my wife I was going to have bacon for breakfast she got really really mad at me. When my friends knew I was eating atkins-style, they thought I was doing a stupid thing and asked me to visit a nutritionist. We need good info to resist all that social pressure. Moreover I didn’t know if I was able to exercise without carbs until I saw you on youtube saying you didn’t eat carbs when the duration of the exercise was less than 3 hours (if I don’t remember wrong). May be in the future NuSI can help change things for a lot of people, but you have already helped a few of us. I thank you for the time you invested writing your posts.

    PD: now my wife also eats low-carb

  • Jilly

    This is a bit off the thread but I suspect it’s mostly about calorie restriction/starvation so I’m going to pop it in here. I was wondering if you had any thoughts on the juice detox craze, juicing and juicing fasts. I’m squarely with low carb myself and anything that involves that much fruit seems like it would necessarily be high in carbs, but the juicing proponents have a lot of claims about huge weight loss, improving health numbers and phytonutrients and micronutrients and the dangers of animal fat. They’ve got pretty good PR and well, they just make it all sound so healthful! I haven’t been able to find a low-carb counterpoint to the juicing claims. Just wondering if you had any thoughts on it. Thanks so much.

  • Tony

    Hi Peter, love your work! Quick question. How can I optimize weight loss with my low/no carb plan that I just started 9 days ago?

    Thanks very much from beautiful Vancouver BC Canada!!

    Thanks very much,

    Tony 🙂

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  • Steven

    I am not trained in medicine or biology, but everything I read about ketosis suggest a that a lot of stored eery is Elim ate via urination. Of ke tones are fact eliminated in this way, than shouldn’t they be included in your first law equation?

    • Steve


      Now that I am on a computer with a real keyboard instead of my smartphone, I will try to ask my question again.

      Like I was trying to say in my first post, the research that I have done suggests that when a person is in a ketosis metabolic state a lot of stored energy in the form of ketones are excreted from your body through urine and breath. So should not this term be included in your first law equation? I know Dr Atkin’s book is fairly old, but his claim was that fat loss via his diet occurred because that a significant portion of the ketones formed from the breakdown of fat stores were peed away. Seems to work for me. I just finished reading Grain Brain by Dr. Perlmutter, which advocates a diet very similar to what Dr Atkins advocated. So last month I gave it a second try and so far have lost 30 pounds. So the results makes me a real believer. Eliminating the GLUTEN has reversed the arthritic pain that I had in my knees and fingers too. My stomach problem have also gone away.

    • Bob West

      Hi Steve,

      I’m not Peter, and obviously I’m not in a position to answer for him.

      However, somewhere on this blog, in a reply to a comment (I can’t find it now), I recall that he said that he had measured the amount of acetoacetone (“AcAc”), the principal ketone that is excreted in the urine, that he had excreted over a 24-hour period, and found it to be very small: I seem to recall, just a few calories’ worth, essentially meaningless. Basically, ketones are being used for energy (principally beta-hydroxybutyrate, “BHB”), not lost in the urine.

      If you think about it, biologically the point of ketosis is to keep us alive by using the energy of our fat stores, not to waste that energy so we can lose weight :).

      I remember the Atkins books, too, and for many years they provided my main understanding of ketosis. However, it looks like our present understanding has gone beyond what he was relying on. Peter and others have updated my information, and, frankly it makes more sense now.

      I agree with you that ketosis is a good way to lose weight, and I have had positive experiences with it too. It just looks like the explanation is different, and perhaps more complex. (I’ll take results any day, with or without explanations….)


      • Correct, it was less than 1 g in 24 hours, so only a few calories. That said, AcAc is not very stable, so it’s possible I excreted more, but only a small amount was measured. Second, because I was in ketosis for so long, it’s possible my body was much more efficient at using ketones, rather than excreting them, ergo, someone just entering ketosis may excrete more.

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  • Brian G.

    Dear Dr. Attia –

    I believe wholeheartedly in the alternative hypothesis that you and Gary Taubes write about so persuasively. And I truly believe that the two of you (particularly through NuSI) will be changing medicine for the better to an extent that is unrivaled by anything I have seen in my lifetime. I feel seriously honored to be able to communicate with you.

    But despite that suck-up intro, I have a bone to pick. Or maybe I’m missing the boat on something crucial here.

    While I know the calories-in/calories-out hypothesis of weight gain is nonsense, it seems to me that there is a danger in going to far in the other extreme by suggesting that a calorie deficit isn’t important when trying to lose weight.

    In other words, assuming an overweight person (me) is functioning well in ketosis for many weeks (which I have been for some time as shown by my O-OHB levels averaging 1.5-2.9 each day), isn’t it obvious that I will lose weight far more quickly/effectively if I take steps to ensure a caloric deficit?

    I have been doing this by tracking my food intake on the Weight Watchers app. (As you know, the WW Points system is glorified calorie counting.) And the weight loss has been coming off quite quickly with zero hunger and cravings.

    I lost nearly 40 pounds (almost all the weight I wanted) two years ago by following WW. But of course, since my nutrient composition didn’t put me in ketosis, this semi-starvation was difficult to follow. The weight came off too slowly for my taste. And of course I had yet another diet failure once I approached my goal. I could not have lived like that for any length of time.

    My experience now is 180 degrees different. I am losing weight far more quickly than before, it is easy to stay within the prescribed amount of points, and I feel great. And I know for sure the only difference is the macronutrient composition of that I’m eating — which as I said keeps me “deeply” in nutritional ketosis.

    I am not trying to endorse WW here. I know there are countless means of tracking caloric intake to ensure a caloric deficit.

    I suppose some could argue that I would naturally eat the same number of calories that I am now so long as I remain in ketosis, but I don’t think so. I suspect I would eat enough to maintain my weight but not lose the average of 2.3 pounds that I have for the past month or two.

    I believe that people who are seeking to lose weight via a LCHF diet/WOL/whatever would succeed much more frequently if they limited their calories too in a sensible manner rather than eat ad libitum. Imagine what the A TO Z study would have shown if the Atkins group also lowered their calorie intake.

    Shouldn’t the message that one shouldn’t be counting calories (see intro to your post) be eliminated — at least as it relates to those trying to lose weight? (I suspect calorie counting will be entirely unnecessary for me once I’m at my goal weight, provided that I remain in ketosis.)

    Or do you feel that my current weight loss rate would be identical even if I were eating ad libitum and consuming 500 more calories per day?

    Thank you!

    • Brian G.

      I should have said that I was losing a WEEKLY average of 2.3 pounds per week for the past month when following WW. This compares to about 1.0 pounds per week last time I was following WW.

    • Barry Fisher

      ATTIA is a super guy in my never to be humble opinion. I’ve admired him for several years now. I just wanted to compliment you on your style re:….”despite that suck-up intro….” He has to dig it. In fact, with your tacit approval I’m going to use it myself someplace someday if you don’t mind. Very cool. Thanks. Take care.

  • Ibrom Evanston

    I have just found out about the low carb diet proposed on your website, The Eating Academy. Although I am trying to follow the diet, I must admit to a certain amount of confusion when it comes to calorie intake.
    It’s easy to see, under your model of metabolism, why a body would not create new fat reserves even when consuming calories beyond it’s needs. Since there is so little insulin to drive that process, fat cells do not take up any excess. But what happens to the excesss? Is it simply excreted?
    Further, if one’s intention is to lose weight, I fail to see how consuming calories in excess of the body’s need will allow this to occur. According to your model, no new fat will be deposited. But what mechanism would prompt the body to preferentially use fat reserves while sufficient, or even excess calories are presently being consumed? I have to be able to understand this.
    Ibrom Evanston

    • Ibrom Evanston

      I would also like to add: Thank you for putting this together. This is a great resource. You do a very great good here.

    • Ibrom Evanston

      I don’t understand why Taubes, et al feel they need to be so cagey about this issue. Never a straight answer to this question. Still, after a ton of sleuthing, here is the answer. YOU MUST BE IN A CALORIE DEFICIT TO LOSE WEIGHT. There, that wasn’t so hard, was it? Yes, it matters tremendously if you are in ketosis. But even if you are in ketosis, you will not lose weight if you ingest calories surplus to what you expend.

      • Not sure what you mean about being cagey. I’ve never met a serious thinker on this topic who suggests weight loss doesn’t imply a caloric deficit. That’s a wonderfully descriptive fact that provides little explanation.

    • Ibrom Evanston

      Peter, thank you for the courtesy of your reply. I am not trying to be simply argumentative here. Indeed, it is only due to Gary Taubes writing, and your website here that I have been able to take the first few steps in the long journey that is reclaiming my health and fitness. Still, when you state in the above article, “Should I be counting calories?” In a word, no.”, this confuses me. Because in order to metabolise my body’s stored fat, I do indeed need to be aware of how many calories my body is expending and how many calories I am consuming.
      Thanks to you and Gary Taubes, I now have a much more fully nuanced understanding of how the food I eat affects my body, and this is crucial. But if the goal is reducing stored body fat, it seems like we come back around full circle to ‘calories in/calories out,” but with a greater depth of understanding of how differing macronutrients have different effects on the body.

    • Paul Arena

      Hey Ibrom,
      When going Low Carb or Ketogenic after an adaptation period, your physiology changes to REDUCE hunger thus making it easier to eat less calories (negative caloric balance). So, ingestion of less calories is an EFFECT of the improved macronutrient profile. When eating a “balance” diet high in carbs it will tend to drive hunger up due to blood sugar and insulin fluctuations. If you believe the causal arrow goes in the other direction than you will be perpetually trying to cut calories below a certain level and most likely will be fighting against hunger, which is doomed to failure in the long run. There is no violation of the Laws of Thermodynamics. Its all about what direction you believe the CAUSAL arrow is pointing in the equation.

  • Magnus

    This is a very interesting article. I particularly like how you turn the tables on the static version of calories in vs. calories out and the [correct] dynamic nature of the thermodynamics.
    However, with the high level material you present in your posts, I seriously invite you to consider that you are wrong about the concept of bond energies as a “storage of energy” in molecules. This is really 101 of Chemistry! Breaking bonds always involves input of energy; there is no energy in the bond that can be “liberated”. It is the sum of
    1) breaking bonds (consumes energy)
    2) forming new bonds (makes energy available)

    that decides if reactions are exothermic or endothermic. If 1) is larger than 2) the reactions are endothermic and if 2) is larger than 1) it is exothermic. Please, have a look at the following passages and compare them with any textbook or even wikipedia on chemical bond energies:

    “[If you’re wondering why fats contain more heat energy than carbohydrates or proteins, it has to do with the number of high energy bonds they contain. Fats are primarily made up of carbon-hydrogen and carbon-carbon bonds, which have the most stored energy. Carbs and proteins have these bonds also but “dilute” their heat energy with less energy-dense bonds involving oxygen and nitrogen.]”
    ”Not to bore everyone with a lesson on organic chemistry, but it’s the actual bonds between these atoms that are responsible for their energy densities. When you “liberate” (i.e., break) the bond between an atom of carbon and hydrogen, for example, you release an enormous amount of stored chemical energy. This table tells you exactly how much energy you would release if you were to break the bonds in these molecules, but that’s all it tells you.”

    It simply does not work that way!!! No energy is ”released” when breaking bonds, you have to put energy in. Hopefully, you have energy available in the system from bonds being formed, otherwise you will have to add heat or sometimes radiation.

    • Nikolas

      Hey Magnus – I think this is where Dr. Attia was going with that statement about bond breaking.

      As long as you accept that the oxidation of carbon fuels is a primary source of energy, and that energy is ultimately used to regenerate ATP from ADP and Pi (inorganic phosphate), it’s like this: the more reduced a carbon atom is, the more free energy is released upon its oxidation.

      A free energy of oxidation (delta G) comparison of a single carbon compound will show this… Methane (-820 kJ/mol) vs. Methanol (-703 kJ/mol) vs. Formaledhyde (-523 kJ/mol) vs. Formic Acid (-285 kJ/mol) vs. Carbon dioxide (0 kJ/mol).

      TL;DR: Carbons in fats are better sources of fuel than glucose because their carbons are more reduced (less oxidized). Just count the number of oxygens in a molecule of glucose and compare that to a fatty acid and my previous statement should make sense.

  • Magnus

    I agree with your explanation of less oxidized carbons in pure hydrocarbon chains vs. partly oxidized CHO being the reason for differences in enthalpies of combustion.
    Already formed C-O, C=O bonds means less energy available when forming new bonds.
    The problem, however, is that I cannot make Peters wording fit with that.
    Bonds are not energy storages! They are sinks. C-C are not as deep sinks as C-O. Still sinks, though!

    For example this: “When you “liberate” (i.e., break) the bond between an atom of carbon and hydrogen, for example, you release an enormous amount of stored chemical energy.”

    No energy is released at this step, on the contrary! The fact that you get energy from oxidizing H and C to water and CO2 at a later reaction step does not change this fact!

    • Nikolas

      Hey Magnus:

      I’d have to say that chemical bonds are indeed stores of energy, or sinks if you will. When you disrupt a chemical bond in the case of oxidizing our fuels (glucose or lipid) we are liberating/freeing the energy that was stored in that bond. Particularly, oxidation will allow H+ (hydrogen cations, protons) to create a Proton Motive Force (PMF) in the inner mitochondrial membrane where the Electron Transport Chain (ETC) passes electrons down their reduction potentials though cytochrome proteins to indeed synthesize ATP.

      So I would say that, yes, energy is released in this series of steps that starts with a reduced fuel (hopefully lipid!) and ends with water and carbon dioxide. Energy input is required to make bonds and energy is given off when breaking them (think, positive or negative enthalpy… in relation to exothermic or endothermic reactions). Weaker bonds are broken to create stronger ones. Inspecting that Gibbs Free Energy (delta G) and Enthalpy (delta H) of the overall reactions of cellular respiration indeed should indicate to us that energy has been liberated from a broken chemical bond.

      Dr. Attia, feel free to chime in if I am misunderstanding your wording. Likewise let me know if we’re still not in agreement, Magnus. 😀

  • Mike

    Thanks for all the time and effort you put into these posts Peter. I have a question I’ve been wanting to ask and I think this is the correct place for it. In your “How I l Lost Weight” post you say “Two things jump out at you, I’m sure: I eat virtually all of my calories in the form of fat and my total caloric intake has actually gone up by about 50%. Let me reiterate, I don’t exercise any more today than I did 2 years ago. In fact, if anything, I probably exercise a bit less (i.e., down from 3-4 hours per day to 2 to 2.5 hours per day).” Aren’t you saying here that your energy expenditure went down, your energy intake went up, and during that time you lost weight? Sorry if I am misunderstanding this and thank you in advance if you can find the time to reply.

    • It appears in me that my non-deliberate EE went up. In my experience this effect is highly variable in people, and may also be transient.

    • Nikolas

      After speaking with and interviewing Dr. Dominic D’Agostino I learned that energy expenditure does go up on a ketogenic diet. Some of the mechanisms he touched on included: activation of uncoupling proteins (thermogenin) in the mitochondria and sympathetic nervous system activation (catecholamines) which directly affect heart rate, blood pressure and body temperature.

      Hope you find that as interesting as I did.

  • Seth

    Peter, for those individuals who are insulin resistant (but not yet diabetic) or who for whatever reason are unable to lose weight despite restricting carbohydrates (and unable to reach ketosis without starving) for over two years, what options do they have other than to experiment with different caloric intake levels? Too few calories means slowing metabolism, too many calories means greater fat storage? I must confess that as I absorb your messages, I am left with a sense of despair because it seems impossible for me to create an environment where my body will achieve a negative fat balance, despite my best efforts to do so. This seems like a needle that can’t be threaded…

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  • Ron

    It’s slow going, but the shift is starting… albeit an odd piece for the Weather Channel.


  • K

    My friends and I are having this debate about the logic behind the 3500 calorie deficiency diet theory… Or whatever you want to call it. Anyways, the easiest basic explanation that I could figure out to explain why calories are not all created equal is to think in terms of a square and a rectangle. For example, to say that because 3500 calories equals 1lb of body fat then to create a 3500 calorie deficit means that you would lose 1 lb. is like saying that because all squares are rectangles means that all rectangles are squares. One truth does not always mean that the “opposite” is true as well. This article is a great explanation of what I am trying to get them to grasp and explains the concept very well.

  • Razwell

    Hi Dr. Attia,

    To quote Richard Feynman on this topic from his book “The Character Of Physical Law” :

    “When you hear of calories, you are NOT eating something called calories, that is simply the amount of heat energy that is in the food.”

    This is in sharp contrast to the “fitness gurus” who always talk about “eating calories.” We eat no such thing.

    These gurus do not realize that the human body derives its energy from the energy in the chemical bonds of the food we digest. This energy is then converted into heat and kinetic energy ( and thought) To write down any precise equation for the total energy balance of something as complicated as the human body would be extremely difficult

    It is worthy to note calorie labels are wildly inaccurate- to the tune of 10 % to as much as 85% off ! – as Dr. Jeffrey M. Friedman ( from Rockefeller University) notes during his lectures. 🙂

    Top biophysicists and physicists gave me some info 🙂

    Best wishes,

  • jo

    Brilliant – I was smiling at the end.
    I have always done a decent amount of exercise. Having put on a stone over the past year, yes I know to increased calories, although with the increase of cycling, up to 200 miles a week…. still the fat gain.
    Having lost weight before on low carb regimes, they do work, but I have always noticed I seem to get more energy and less lethargy from fats; ie Avocado… suggesting this to people, brings you back to ‘oh that’s really fattening’…. Hmmmm I can honestly say I’m looking forward to this little food intake change and to see what happens over the coming months !
    Although…. what do I do on the cycle club run cake stop ?!

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  • Tim Lewis


    I find your postings, blogs, writings, etc, fascinating. I know nothing about most of it. I’m just a 52 year old chauffeur with chronic lower back pain that happened upon your site in search of a connection between diet, my back problems and anti-inflammation. A little weight loss wouldn’t hurt either. As I have concluded after reading a lot on the subjects over the last several months, the low-carb or now the very low-carb diet seems to be garnering more authenticity. What makes your work so interesting is the technical, actually very technical, explanations. I look forward to reading more from you in regards to eating for overall good health! Oh, and your children are adorable.

    Thanks again,


    • Thank you, Tim. Hope your back is on the mend.

  • willam reichert

    I agree with every thing you say but I cannot for the life of me figure out why my girl friend who I love dearly eats a very high fat low carb diet and remains 45 pounds over weight .

    • Very frustrating for her, I’m sure, but unfortunately not that uncommon. More so in women than men. I think about this phenomenon more than most others, but commenting on it thoughtfully is beyond the scope of a comment/response.

    • Sherry

      I just found this site and am hoping to find some answers for the same issue. I’ve tried paleo, keto, AIP and others and still am having a heck of a time keeping the weight off. Maintaining is a very careful balance and some days it works and some days it doesn’t. I cannot figure out what is keeping me about 25 over my goal weight either! 🙁

  • Joanne

    Just completing 22 months on a very low carb diet (aiming for 20 gm a day). Initially lost 20 pounds in the first 2 months, then stalled, treading water around 211 pounds for 20 months. As you say, very frustrating. Early on I was using the inexpensive urine strips that never (maybe once) showed any ketosis at all. Very frustrating. Two months ago I got a Ketonix breathalyzer from Sweden. It shows I am everyday in the red (high) or in the yellow (medium) range of measured acetone in my breath. Everyday. Surprising. If the Ketonix is accurate, I’m in ketosis every day since I started using it 60 days ago. Wow. But, no budge on the weight.

    I first became obese at age 6 way back in 1954 after a bout of Scarlet Fever. Consequently, I’ve spent 60 years dieting, often very successfully, but still the life long pattern is gain, lose, gain more. I was at a lifetime high when I started this latest iteration of dieting. About 6 years ago I had tried the low-carb diet and in about 4 months lost 60 pounds, which is why I went back to low-carb this time, but as I said, this time very different at only 20 pounds lost in 22 months. Very frustrating.

    My hope is that the other benefits of low-carb are still happening even without weight loss. At 67, my blood measurements are good, and I don’t take any prescription meds. So, that alone is encouraging me to stay low-carb. My family is riddled with diabetes (from way back, long before it became epidemic). All four grandparents, one parent, and now my younger brother developed (old-age) diabetes. So far, I’ve no signs of it. My GP scolds me for asking about it at every visit. But at my age, weight, and family history, I don’t see why diabetes won’t suddenly develop.

    In 2005, I developed symptoms of a blood disease that causes lymphocytes to over-produce a protein, that then thickens the blood. I’ve been treated with monoclonal antibody infusions for the past 4 years, and eating low-carb for the past, as I say, 22 months. At every visit, I remind my hematologist that I’m eating low-carb. He nods and notes that my blood measures, other than the viscosity, are good. I am hopeful, from my readings, that low carb is better for proliferative diseases, than high carb would be, even if only marginally. What is it they say, feed a fever, starve a cold?

    In the last 9 months, my nose-bleeding episodes have stopped (holding breath, as it could be just a pause). Nice, and now if I could just lose some weight, it would be so nice.

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  • JohnK

    Hi Peter –

    I have recently changed the way I exercise, and was looking for information on how weight training can affect Resting Energy Expenditure. I came across this article which makes the case that high-intensity interval resistance training (weights) results in higher REE than traditional weight training. Evidence from my N=1 experiments seem to confirm this work.

    Best regards.


    Cite this article as:
    et al.
    High-Intensity Interval Resistance Training
    (HIRT) influences resting energy expenditure and respiratory ratio in
    non-dieting individuals.
    Journal of Translational Medicine

    • Michael

      Hey John K

      Are you using the Doug McGuff Method of HIT ? If not , which one? I am in the process of changing my workout routine also. How long are you going between HIT workouts? Do you do split sessions? ( Arms one day , leg another ,etc) Do you engage in other sports or lighter workouts in between HIT?
      I am especially interested b/c I am a primary doc. The more I can confirm the value of HIT the more I can recommend to others. I reviewed the Paoli paper and as a scientist I can tell you it looked weak and full of holes to me.

  • James

    @AstroSamantha tweeting about leaving the milk unopened in space made me wonder: Is there not precise nutritional intake/body compositional results available from NASA? Weightlessness may confound things but surely they are worth a look at, no?

  • RichardH

    Hi Peter,

    I have been following you from a month or so ago and I can definitely say you have impacted my life, thanks a lot for the work you have been doing.

    I want to share what I’ve been doing the last month which seems to fit perfectly that diagram of (what we eat – Digestion, exercise, daily activity and basal expenditure) WITH the arrows.

    First of all a little background, I have lost 50lbs in the last year and a half by the conventional method of exercising and “eating better”, by accident that “eating better” was actually a gradual reduction of carbohydrates (but still avoiding fats so I was consuming lots of protein and my carbs were coming from fruits). My transition was very similar to yours and that’s why in the last month when I started nutritional ketosis, it did not affect me that much (didn’t get the “keto flu” symptoms)

    Now here is the interesting part. From 40% body fat (aprox) I have reached 23% (before nutritional ketosis). In the last 3 full weeks of me being in ketosis, I have maintained my routine of lifting weights and playing tennis (notice that all my activities are very anaerobic) During those 3 weeks, I lost 5lbs in the first week (water retention) and then I just got stuck and did not see any fat loss. I was eating whenever I was hungry and was not restricting my calories purposely. During that time I was consuming approximately 2,600kcal per day which means I was eating at maintenance.

    Here is where it gets more interesting. I thought that maybe even though I was in ketosis, my body was not using ketones that much (due to me doing mostly anaerobic exercises) so the only thing that I changed was include a daily fast walk before my first meal of the day for 40 mins. Not really sure if I was at the sweetspot of where my body would love ketones, but I may have been pretty close.

    To my surprise, the last couple of days of me including these fast paced walks, I can go longer without eating, I am simply not hungry for a longer time. Does this mean that I needed to do these walks to teach my body to use the ketones? Maybe for the previous weeks I was in ketosis but my body was not using them at all? (or very little)

    It’s amazing how your depiction of the arrows came into play here… included a more aerobic exercise and now I want to eat differently than before. My hunger was suppressed for so long that I couldn’t even hit my minimum protein target per day to avoid muscle mass and that is the only thing I am going to be very careful about from now on with this change. I am excited to see what will happen in the next few weeks. I will keep doing this walks and keep my anaerobic exercises as well and make sure I am getting at least 1.5g of protein per kg of body mass.

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  • Michael

    I violate thermodynamics all the time. I am eating between 3000-4500 food calories per day with a macronutrient split pretty close to 50% carbs 30% protein 20% lipids and I only weigh about 140 lbs with a 5 foot 9 inch frame. I can see my abs no problem.
    Exercise? 10 minutes of low intensity stairs to warm up, then five sets of five squats, five sets of five deadlifts, and that’s about it. The rest of the day I sit on my fat–I mean I sit on my skinny ass. I’m actually trying to gain weight though. I make sure to top off my blood amino acid levels every 2 hours with 20-25g protein and eat a salad every day with the rest of my meals for more micronutrients (especially folic acid since it’s required for cell division). I’m an om-nom-nomnivore who enjoys meat, fish, rice, potatoes, vegetables, and milk. I kinda like beans but they digest too slowly for me to realistically get enough calories in my day, even in spite of all the fiber they’ve got in them.

    All of which brings me to a question that I wonder if you can answer: how much of a calorie-sink is it to grow facial and bodily hair? If I were to destroy a bunch of hair roots (e.g. electrolysis) how much closer would I get to positive energy balance, and what are the physiological and social consequences of doing so?

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  • Lori

    Great information. My question was not answered though and I’m hoping it’s a simple one to answer…most of my life I have been overweight…after marriage, 3 children and age hit me, I became clinically obese. After embarking on Isagenix, I have lost 25 lbs and a ton of inches. However, the plan is a stickler for 1200 calories per day, mostly protein, and I am having a very tough time getting 1200 calories in. I have always been the type of person that can go a whole day without eating and still feel ok. Maybe that’s why I have always been overweight. I am told if I do not consume at least 1200 calories a day my body will store, store, store fat. I’ve found that I’ve plateaued in my weight loss after a month and a half and I still have more to lose. So, my question is this, if I put something in my mouth every 2 hours or so, ie: rice cake with hummus, 1 slice of Ezekiel bread with almond butter, will my body still see it as being fed and continue to metabolize or do I have to stick to at least 1200 calories a day?

    Thanks for the advice!!


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  • Mike

    Dr. Attia,

    Does consuming BCAA supplements kick you out of ketosis by gluconeogensis?


    Mike J.

    • Typically not since they are consumed in small amounts.

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  • Bob Lamb

    Discovered your site reading about UCAN. Very informative! I’ve got my head chopped off making some similar statements you have made on myfitnesspal including breaking laws of thermo and believing in unicorns. I appreciate the complexity you go into. I have a B.S.M.E. and a M.S.E.E in cotrol theory and am very familiar with dynamic systems, feedback loops, and non-linearities. I don’t know physiology though and you site helps.

    One thing I haven’t seen you discuss yet is effects of saturation and rate limiting of the processes you describe. All real systems have these limitations. If you eat big meals, you absorb less than if divided up into smaller meals. That is the hypothesis.

    I’m on a 21:3 IF diet and have lost 38 lbs in 23 weeks (more like 21 weeks since I relaxed diet over Christmas holidays). I want to get a keytone meter to see how much keytones I’m producing. Trying to get back to running (ex 800m track guy in college). Age 54, sw 252, cw 214.


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  • Bob Lamb

    Seems like your saying that:

    A calorie surplus is a necessary condition for fat storage but is not a sufficient condition.

    A calorie deficit is a sufficient condition for fat burning but may not be a necessary condition. As time progresses,, the body will adjust and a person will not be able to continuously keep a calorie deficit to lose weight.

    Did I get it right!? Thanks.

  • Peter Dove

    For me personally, if I don’t get 2500 or more kcals per day, then I start to feel it. Seemingly it doesn’t matter how active I am, any less than that and I’ll start to feel really exhausted. Mind you I’m currently suffering from some level of adrenal burnout, probably phase 3, so I’m sure my required calorie intake is affected a lot by this!

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  • Autumn

    My husband has the opposite problem as me! He is currently trying to gain weight and bulk up by upping the calories, protein, and weight lifting. It doesn’t seem to help, however. Do you have any reliable resources you could point me to to learn more about what kinds of foods and eating ha bits will help with this? I love the article. It makes clear that simply counting calories t is not an effective way to gain or lose weight!! And personal experience attests to this.

  • Michael

    Excellent blog, Dr. A. I’ve been on a ketogenic diet now for about a month and a half. I have quite a considerable amount of weight to lose and so far I love the keto lifestyle. As I never was necessarily a great lover of sweets and other carbs (although I could certainly destroy a nice warm homemade sourdough bread) it hasn’t been particularly difficult for me to maintain an extremely low level of carb intake, generally less than 10 grams per day. The carbs that I do ingest come from leafy greens and some cruciferous vegetables. I do have a couple inquiries if you could indulge me. I have never had to take blood glucose levels as I’m not diabetic. My brother, however, is. I happened to be present last week when he took his glucose level and I asked him if he wouldn’t mind if I tried it. I had been fasting at that point for approximately 12 hours. To my consternation and amazement my blood glucose level was 35mg/dl. I was in such disbelief that I used a control test sample to make sure the meter was calibrated properly. Tested again at 37. Went out and bought my own meter to keep tabs. I felt absolutely no ill effects whatsoever. In fact, I felt quite well. In the following days my glucose level resolved slowly and now hovers around 70-75 fasting, a tad higher after a meal. Any hypotheses on what caused the abnormally low levels? I thought perhaps an insulinoma, but my insulin levels came back as quite low (can’t recall the exact value at the moment). Another question, because of my ultra low carb intake, many days zero, do you think that a higher protein to fat ratio would be prudent, to allow for slightly higher gluconeogenesis in the absence of carbs? Thanks for the great service that you provide in disseminating knowledge of a field that can be maddeningly convoluted, complex and seemingly ever-changing.

  • Jadzia Woods

    This was very informative and I have taken away that genetic makeup can also effect a person’s weight, because of the way their body deals with fats, or that Current Dogma doesn’t even worry about what it is that you eat but that is all about the calories. I also never knew in order to be considered a calorie it has to raise a gram of water one whole degree. I always though for something to be considered as a calorie it just had to have energy.

  • America Trejo

    hi peter, I am a student from cod.
    The 3 main take away that I read from your article are how when someone says a gram of fat has 9 calories, they actually mean 9 kcals. I didn’t know that it was very interesting thing to read.
    the second main take away is about the twins, how they eat the same thing but have different calories. Its really mind blowing. The 3rd main take away is Fats are primarily made up of carbon-hydrogen and carbon-carbon bonds. very interesting thing to read.

  • Cretsinger Veronica

    Hi Peter,
    I’m a student at COD. the 3 main points I got from this article are that your body can expend only so much and if you eat more calories than your body can expend, you end up gaining weight. The second thing is that what you eat actually changes how you expend energy. The third thing is that every one accumulates different amounts of fat, and is very interesting to see that this can also happen to identical twins.( who are technically the same person)

  • Jalen Gilmer

    Hello, my name is Jalen Gilmer. I am a student at COD, going for a fitness certificate and trying to be a personal trainer. The main 3 things I learned are if I’m going to be always exercising, I shouldn’t eat less because I have a fast metabolism. I also learned that if I have a bad diet, all the exercising and activities I do will go to waste. I also learned that people with large frames trying to maintain a healthy weight should eat a lot of calories, healthy ones though. Thank you for the advice, I will use this as a tool in my journey.

  • Matej K. Kokot

    Hi Peter!
    I’m posting a question here, because I can’t find the direct e-mail, i do apologise… As a working m.d., that was thought the dogmatic “low fat, long life” principle, and I’m slowly chewing through the twists and turns in the medical literature in the last 5-10 years concerning metabolic syndrome, fructose, exercise, cholesterol and obesity. And frankly I’m amazed how could all those poorly conducted or so heavily biased studies ever be a baseline for medical recommendations pre 1980s. The main reason I posting here is because I can’t find any relevant data to answer my questions, and I’m wondering do you, as a master in this field, have any in your sleeve. I would die to know:
    1. Do people on a high calorie (but sucrose or HFCS free) diets still get liver fat accumulation or fatty liver disease?
    2. Do people on a high fat, high calorie diet increase their subcutaneous fat, (if eating more that their RDI, or eating until not hungry any more).?
    2. If the answer to previous 2 is no – is it possible that high fat diet is self limiting (calorie-wise) on the visceral transporter – is there any data to support that?
    3. One thing I’m sure about cholesterol (and/or lypoproteins) is that I don’t have any clue anymore what the exact role and transport mechanisms of all branches of cholesterol carrying vehicles are…:-) The exercise is known to raise HDL – which mechanism do you think is most likely behind this?
    4. As an extreme case – do you think it’s possible to reverse the effects of metabolic dysfunction just with the diet alone, with no physical exercise, or in extreme cases with keeping a sedentary lifestyle (<1,5 MET)? (don't get me wrong, I work on an "exercise prescription for health" project, but since I'm throwing away a lot of learned stuff, why not challenge my on field too.
    4. You've reduced your amount of body fat significantly – the common preaching is that the amount of fat cells you gain during your fat years could never be reduced, supposedly we just shrink their size – have you any ideas how did it go with you on a ketogenic diet – did you get less fat or less fat cells?
    5. what's the most practical method to assess insulin resistance?
    6. I can't seem to loose the bad feeling that we're doing the same with sodium in hypertension as we did with cholesterol (daily fat intake) and CHD – the problem I see, but can't find any studies, on it is a cascade reaction to other minerals…Do you have any studies backing up sodium cascade? Maybe the majority of the hypertensive effect comes from fructose toxicity after all as suggested by prof. Lustig…
    7. prof. Ron Moughan did a great presentation on the history of low carb vs high carb diets in physically active people, and the story goes remarkably back (pre 1900). There seem to be some sort of consensus that a HCHD requires lower oxygen cost than a HFD. But your ketogenic diet, or better BHB experiment suggests that the oxygen cost is even lower than that of HCHD? with 1l we get 4,7 kcal when burning fat or protein but 5.1 kcal when burning CH – what's the number then for BHB?

    Thank you for your answers, your time, your openmindness and self experiment data sharing. Greeting from Slovenia.

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