Stephan Guyenet's critical examination of Gary Taubes' anti-carb book, Good Calories, Bad Calories

Stephan Guyenet, a neurobiologist who studies the neurobiology of body fat regulation, wrote a long, detailed critique of Gary Taubes' book, Good Calories, Bad Calories on his terrific blog, Whole Health Source.

A couple of weeks ago on Gweek, I reviewed Taubes' followup book, Why We Get Fat: And What to Do About It, which is a slimmed down, easier-to-grok version of Good Calories, Bad Calories. I hope Taubes responds to this interesting critique. But he hasn't posted to his blog since April.

What I want to discuss is a hypothesis.  It's the idea, championed by Gary Taubes, that carbohydrate (particularly refined carbohydrate) causes obesity by elevating insulin, thereby causing increased fat storage in fat cells.  To demonstrate that I'm representing this hypothesis accurately, here is a quote from his book Good Calories, Bad Calories:

This alternative hypothesis of obesity constitutes three distinct propositions.  First, as I've said, is the basic proposition that obesity is caused by a regulatory defect in fat metabolism, and so a defect in the distribution of energy rather than an imbalance of energy intake and expenditure.  The second is that insulin plays a primary role in this fattening process, and the compensatory behaviors of hunger and lethargy.  The third is that carbohydrates, and particularly refined carbohydrates-- and perhaps the fructose content as well, and thus perhaps the amount of sugars consumed-- are the prime suspects in the chronic elevation of insulin; hence, they are the ultimate cause of common obesity. 

There are three parts to this idea.  I'll discuss them each separately.  I know many people are expecting (hoping for?) a bitter takedown of Gary Taubes, but that's not what's going to happen.  I don't feel bitter, but I do think some scientific wrongs need to be righted, for the sake of the ancestral health community as a whole.  I also acknowledge that there is a lot of useful information in Taubes's books. 

Part I: A Defect of Fat Metabolism?

The first part of this hypothesis states that energy balance is not the ultimate cause of fat gain, it's the proximal cause.  That is, Taubes is not disagreeing with the first law of thermodynamics: he understands that fat accumulation depends on how much energy is entering the body vs. leaving it.  However, he feels that the entire industrialized world didn't just wake up one morning and decide to eat more calories, therefore something must be driving the increased calorie consumption.

He cited the research of Drs. Jules Hirsch and Rudy Leibel, various underfeeding and overfeeding studies, lipectomy studies, and evidence from genetically obese rodents, to demonstrate that body fatness is biologically regulated rather than being the passive result of voluntary food intake and exercise behaviors.  He then advances the idea that it's an alteration in this body fat regulatory system that is behind obesity.  This may sound familiar because I've written about it several times on this blog.  So far, so good.

This is where he should have mentioned leptin signaling, which would have taken the book [in] a scientifically accurate direction.  Leptin is the system that Drs. Jules Hirsch and Rudy Leibel have shown in carefully controlled human studies is responsible for the metabolic defect he's getting at (1).  It's also the system that is mutated in the genetically obese rodents he discusses (2, 3).  Yet it receives no mention in the book.  This is a fork in the road, where Taubes discards a plausible hypothesis in favor of an indefensible one.

The Carbohydrate Hypothesis of Obesity: a Critical Examination


  1. well, i’m one of those who won’t gain weight at any cost, and I mostly eat lots of carbohydrates. noone ever looks into the cases opposite of obesity for their theories of healthy food.

  2. I found I was eating for blood sugar levels rather than hunger, and staying pretty fat. Removing carbs fixed that in enlightening style. Now I only eat oaty stuff for breakfast.

  3. I’m a pretty big fan of Taubes, and we all owe him a debt of gratitude for debunking the diet-heart disease hypothesis in GCBC.   But Taubes’ carbohydrate theory of obesity has pretty much been debunked, yet he continues to cling to it.  

    Taubes disappointed many of us at last week’s Ancestral Health Symposium by confronting Guyenet (and arguably insulting him) during a Q&A session.  Guyenet’s posting is in response to that event at the AHS (look a couple of postings back in Guyenet’s blog).

    The current thinking (subject to change) is that the low-carb diet is effective not because of the low-carbs, per se, but because low carb diets go a long way in reducing the Neolithic Agents of Disease (NADs) that humans have been introducing into the diet since the advent of agriculture.

    Required reading:, hub of all things paleo , home of the Ancestral Health Symposium , Guyenet’s blog.  Very good reading , blog of Kurt Harris, M.D.  Excellent stuff here.

    Edit: I meant to note that I’ve been VLC for about 10 years, but I’ve recently overcome my carb phobia.

    1. Mike,

      Your body will make the sugar necessary for your brain.  So no your body doesn’t need carbs, though infants body does need fat for proper brain development.  That is why pediatricians recommend whole milk for children under two.

      Further, there are entire societies who subsist entirely on meat and thus ingest virtually all meats and no carbs and they are perfectly healthy.


      Joe Dokes

      1.  Further, there are entire societies who subsist entirely on meat and thus ingest virtually all meats and no carbs and they are perfectly healthy.

        Which societies are these? I am pretty sure that every society relies on grains and legues along with any meat they might eat.

          1. If that’s the example, then Joe Dokes’ comment is wrong on two parts. 
            1. There is one society not societIES
            2. It’s not “perfectly healthy” as their life expectancy is over a decade shorter than the average Canadian’s

            Diet may not be the only factor, but clearly that’s not a good example of humans thriving on a carb free diet, it’s a case of humans getting by on a carb free diet, but fairing relatively poorly

          2. But I think that’s what I’m getting at, the original claim that there are “perfectly healthy societies” eating almost exclusively meat, is untrue. It’s as untrue as saying that it’s “perfectly healthy to subsist on fast food.” Surviving and being perfectly healthy are two entirely different things. It may be possible for some individuals to eat only fast food, and also be healthy but there are not societies thriving that way, nor do there appear to be any societies that thrive eating only meat. The fact that societies that do so also tend to live places where agriculture isn’t an option, may suggest that there are factors other than diet at play but until we can control for those other factors, I wouldn’t use these cases as examples for why carbs are bad.

          3. The health of the Inuit nations has declined since adopting a Western diet, but explorers and medics living among them a century or so ago noted their robust health and their lack of “ordinary” diseases, especially cancer and heart disease. Sadly, like many other First Peoples, they are now among those who suffer the effects of the Western diet most heavily. 

            Other traditional peoples that ate a meat-heavy, nearly plant-free diet are several groups of Plains Indians, and the Maasai of Kenya, whose warriors refused all plant foods, except medicinal herbs. Here’s a brief introduction to historical/traditional low-carb ways of eating:

    2. I get all my carbs from fruits and vegetables, which also deliver fiber and micronutrients. The problem is getting your carbs from school paste – pasta, bread, etc.

  4. Sorry, I’m too critical of a reader.

    Flashing red stop signs: “alternative”,  “hypothesis”,  “perhaps” and “proposition” FOLLOWED UP BY:
    “are the ultimate cause”. My brain turns this into a math equation and it comes out total bunk. 

    I call the use of these types of “disclaimers” as ‘I guess” phrases. 

    This, I guess my guesses concering obesity constitutes three distinct guesses.  First, as I’ve said, are my basic guesses that obesity is caused by a regulatory defect in fat metabolism, and so a defect in the distribution of energy rather than an imbalance of energy intake and expenditure.  The second is that insulin plays a primary role in this fattening process, and the compensatory behaviors of hunger and lethargy.  The third is that carbohydrates, and particularly refined carbohydrates– and I guess the fructose content as well, and thus I guess the amount of sugars consumed– are the prime suspects in the chronic elevation of insulin; hence, they are the ultimate cause of common obesity.  

    All I have to do is consider  if the hypothesis or the author is defective. And the hypothesis didn’t write itself. 

  5. Effective dissection of Guyanet’s critique by Andreas Eenfeldt, MD here –

    Three main points which are: hyperinsulinemia results in leptin resistance, long term hyperinsulinemia increases fat storage and makes us eat more and there are lots of studies that show that low carb diets reduce insulin levels.

    1. I’m sure he makes a lot of great points but his first paragraph starts with a straw man argument…

      “Stephan Guyenet has posted on why he does not believe in refined carbohydrates as a cause of obesity”

      That is just. not. true.  sorry :-)

    2. Thanks for the link to Andreas Eenfeldt.  There was something fishy about Guyanet’s complicated arguments and she nails it.

      The interesting thing is it seems Taubes main argument is against what Guyanet says is unarguable.  Thermodynamics.  That weight has to be connected to energy in, energy out.  But you don’t have to be a scientist to realize the human body is more complicated than that (even ignoring how much food and what kinds of food simply pass through the body as waste).  Even a rocket ship burns different kinds of fuel with different efficiency.  That the crudest form of thermodynamic reasoning took over in the 1960’s as the key dietary advice seems to be the source of a lot of current problems with obesity.   Yet Guyanet just throws it out again as if anyone who questions the logic of it thinks the Earth is flat.

  6. Because, Ben, none of the science actually supports that and it’s only been conventional “wisdom” since the early 60’s.  Prior to that in most of recorded human history people understood that you get fat from eating sugary foods, starches, refined carbohydrates.

    It was self evident back then because those items were not the staple of the diet as they are now so you could clearly see that people that ate an unusual amount of those foods were obese and the rest weren’t in most cases unless they had a genetic pre-disposition to fatness.

    1. well people lead more sedentary life’s now, so they don’t need as much food, that doesn’t stop them from eating more than they need though.

      But umm can you tell me the difference between a refined carbohydrate and an unrefined one, do they have different energy content?
      why starch? people have been eating starch for a long time before obesity took off.

      1. Refined carbs are easier for the digestive system to break down and therefore they raise blood sugar more quickly/steeply. At least that’s how I understand it. I could be wrong.

  7. I do not want to go into long discussions about it, but would tell something from my experience of being fat and having a sedentary job.

    If I have access to decent salad bar, I’m eating 2-3 times less than usually and lose weight. (My base salad being: rucola, cut carrots, red beans, corn, tune fish and bit of olive oil.) I also need to eat only once or twice per day: I do not have random appetite spikes.

    I I do not have access to salad bar, I’m eating three times per day and sometimes evening snacks.

    What I’m trying to say here, from my own experience and experience of few other people, as long as body doesn’t get the doze of all nutritional elements it needs (acids, salts, vitamins, etc) it would feel hunger. Amount of calories in my experience is secondary. IOW, looking at the steak serving, it is not the steak which gets you through the day – it is the side dishes.

  8. I’ve never read Taubes… and, as far as carbs go, I only know how they effect my body. 

    I personally find that the more bad carbs that I eat (Chips, bread, sugary things, fries, etc..) the more my willpower to eat well diminishes. 
    If I keep carbs to a minimum, and eat them in whole grains, nuts, etc.. I find that I can maintain control over what I put into my body and feel zen about it. Carbs aren’t the enemy, yes… we need them. But personally, I have to take them in limited quantities. 

  9. I think the point is that no one ever went broke writing yet another FAT book that denies there’s a relationship between consumption and weight.
    The human body does not have a single clear cause for a given effect. The feedback loops and cascades quickly fill a whiteboard. “Simple answers” come from simple people.

  10. I used to be in the “Thermodynamics!” group, but recently I realized something. Weight loss does obviously depend on calories in being less than calories out. But while we have total control over calories in- no one is forcing food down our throats, and no matter what cravings our bodies throw at us we always have to make a conscious choice to eat any particular piece of food- we have only partial control over calories out. Our bodies control how much muscle tissue to maintain, how much fat is eliminated in stool, and how much energy to devote to a whole bunch of other metabolic activities, all outside our control.

    Next thought: the first question for any diet needs to be: does it provide adequate nutrition? There are essential amino acids, essential fats, essential vitamins and minerals, but no essential carbohydrates. So if you had a decent diet but were just eating too much, the portion that could be most easily reduced without affecting health would be your carbs.

    Also, I recently read some blog posts about a study showing even *after* you control for total calories consumed, people who eat more fruits and vegetables lose more weight. Starchy vegetables, white flour, and refined sugar were a contributing factor in weight gain.

  11. Hi Mark,

    Thanks for the link!  BoingBoing has been on my blog sidebar for three years.  It’s required reading for me.  Cheers,

    Stephan Guyenet

  12. By the way, there are several tribes in Africa whose entire tourist based economies require them to eat strange diets in order to lure western scientists to study them. 

  13. Folks, the problem is that our food has changed, primarily through breeding variants that deliver more weight-per-unit for the food industry.  Thus the wheat used to make your bread is not the same wheat we ate 50 years ago – the kernels are fatter and starchier. 

    The Chorleywood bread making process further introduces crap into the food chain. I can’t eat almost any bread produced in the UK anymore but when I do find *real* bread I munch it down in delight.

  14. What I find kind of disappointing about this post is that it seems to set up a boxing match between ideas. Any real scientist knows that all models are wrong but some are useful. I’m sure Taubes is wrong and I’m sure that this so-called “takedown” of him is wrong too. Promoting this as a boxing match does little to help us understand the domain and refine our models so they can be a bit more useful. 

    I think it’s flat out wrong to back Taubes into a corner and suggest that the other person is attacking him. This just increases his resistance and makes it harder for him to help us find the best answer. It’s not a boxing match.

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