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. 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.

  2. 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?

  3. 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.

  4. 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.

  5. 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.

    • 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).

    • 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: https://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.

  6. 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.

  7. 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.

    • 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.

  8. 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


  9. 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.”

  10. 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.

  11. 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!

  12. 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.

  13. Hi Peter,

    I came across this study https://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).

    • 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.

    • 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.

    • 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.”

    • 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.

  14. 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?

  15. Hi again Peter,

    Sorry for bringing up all these studies but I think this one https://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?

  16. 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,


  17. 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.

  18. 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.

  19. 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.

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