February 29, 2012

Nutritional Biochemistry

Do calories matter?

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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  1. Read your post then saw this in the NY Times:https://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).

    • 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.

    • 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.

    • 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.

  2. 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.

  3. 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.

    • 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.

    • 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 . . . ;).

  4. Peter,

    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.

    • 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.

  5. 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!

  6. 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.

  7. 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

    • 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.

  8. 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.

    • Stan,
      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?

  9. 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.

    • 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]).

  10. Peter,
    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.

  11. 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.

    • 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.

  12. 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.

  13. Peter,

    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.

  14. 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.

  15. 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.

    • 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?!”

  16. 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.

  17. 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

  18. 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.

  19. 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.

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