Professor Ludwig vs. Stephan Guyenet on insulin vs. calories

Is our weight mostly controlled by hormones or by the brain? Is it about normalizing our fat-storing hormones (mainly insulin) or is it just about deciding not to overeat?

The second answer has been the most commonly believed one, and it’s been a giant failure. We need new ideas that actually work. So we need to find the truth.

The old arguments in this interminable debate are nicely packaged by the formerly popular blogger Stephan Guyenet, PhD, at Whole Health Source: Always Hungry? It’s Probably Not Your Insulin

As a reply Professor David Ludwig just published this: Ludwig Responds to Whole Health Source Article

Who wins?

So who wins? The way I see it they are both wrong, but Professor Ludwig is much less wrong. 

Insulin levels and future weight gain

The argument from Guyenet that “High insulin levels do not predict future weight gain” and calling it “a basic prediction of the hypothesis” is simply based on a misunderstanding. Of course it does not. High insulin levels just predict (very accurately) already being obese.

I don’t think Ludwig answers this quite right. This argument from Guyenet is silly and needs no high science to answer.

If high insulin levels predicted future weight gain then obese people (who almost always have high insulin) would blow up like balloons. They would never stop gaining. In fact they would gain weight faster and faster until they exploded á la Monty Python.

Conversely, if low insulin levels predicted weight loss then thin people (who almost always have low insulin) would continue losing weight forever, until they disappeared.

Of course, neither of these ludicrous predictions are ever going to happen. Instead the body quickly reaches an equilibrium, where a certain average insulin level corresponds to a given fatness level. This is why obese people often maintain about the same body fatness over years or decades.

So: High insulin does not predict future weight gain, it predicts already being obese.

Weight Control – A Question of Calories or Insulin? – Dr. Andreas Eenfeldt
This correction also invalidates Guyenet’s following argument, about a there not being a “positive feedback” when losing weight. Again, of course not.

I discuss these misconceptions in more detail in a 2015 presentation (click image to the right).

Where Ludwig may be wrong

I think Professor Ludwig (as well as Taubes in GCBC) over-simplify the idea of “internal starvation” as a driver of weight gain. As Guyenet rightly points out, blood levels of fat and glucose on average tend to be higher in people with obesity.

Professor Ludwig does not have a fully satisfactory answer here, even if he correctly points out that episodes of low blood sugar is common some time after consuming high GI carbohydrates.

Probably a more correct way to look at this is to not only consider absolute levels of fat and glucose, but also changes in these nutrients. I.e. rapidly falling levels of nutrients in the blood may trigger hunger. Even if they are only falling lower than what is normal in the obese individual, not necessarily lower than what is normal in thin people. The body only knows itself.

Bottom Line: What works?

While it’s highly exciting to watch scientists disagree and quote studies, there is something more important: What actually works? How do you eat to lose weight?

People have been losing weight for hundreds of years using low carb. Conversely people have been gaining unprecedented amounts of weight for decades, just trying to eat less.

At least 20 high-quality weight loss studies back this up: low carb simply works better. More weight loss – with no need for hunger or calorie restriction.

It just works.

Try it for free

Low Carb for Beginners

Take the 2-Week Low-Carb Challenge

Do you want MORE science stuff?

How to Lose Weight – the “Magic” vs. the Insulin Way

Always Hungry? Here’s the Book for You


  1. George Henderson (@puddleg)
    In my understanding, "internal starvation" can also be a matter of substrate cycling. For example, in diabetes glucose is taken up by the liver, independent of insulin, due to its elevated concentration, undergoes glycolysis, is converted to acetyl-CoA and oxaloacetate, then merely used to make more glucose, because glucagon dominates. Fatty acids are similarly cycled to other fatty acids. These cycles waste most of the energy they produce. So starvation is relative. Diabetes is an extreme example, but it''s likely that similar things happen whenever the metabolic hormones, especially insulin and glucagon, are over-supplied and out of balance, and whenever substrate is excessive, as it will be during weight gain or steady-state obesity.
  2. Mathieu
    When I read GCBC I remember having a very different understanding of "internal starvation". My impression was that this starvation was at the cellular (non-adipocite) level and caused by a defect in fuel partitioning, which ends up manifesting itself as psychological hunger.

    I remember him citing examples of mice studies where the hormonally "broken" mice would even waste organ tissue to the point where they died of starvation with a significant amount of remaining body fat. The idea is that fuel partitioning can be altered with low-carb in a way that there is less of this cellular starvation which would manifest itself as lower psychological hunger, and would be one reason why hunger auto-regulates on low-carb.

    This might be totally false, and if its true the actual mechanisms are definitely not worked out, but that is what I took Taubes to mean. Was my impression way off?

  3. Nate
    Well, as T1D, I can say that i have experienced Dr. Eenfeldt's theory that hunger could be dependent on the speed of blood sugar lowering. While I was eating a high carb diet, a mistake in balancing my food intake and insulin doses could cause a rapid lowering of blood glucose and thus intense hunger. Trying to only eat a small amount of glucose to bring me back to a normal blood sugar level took a lot of discipline, which most often rapidly decreased also. LCHF has reduced that intense hunger a lot. Hunger is truly a relative thing.
    Reply: #6
  4. Mike
    I like how Andreas refers to Guyenet as "the formerly popular blogger".
  5. Ian
    Most of the stuff in GCBC comes from Gary Taubes's interviews and exhaustive (he jokes "exhausting") research pertaining to work done over 50 years ago. It seems to me insulin must be a major culprit in metabolic syndrome, possibly synonymous with it, and failure to burn ketones will probably prove to be the key. But Taubes hasn't stopped there. His non-industry funded organization, NuSi, is putting their money where their mouth is, and testing these claims.
    Fructose and leptin are clearly also involved, as are undoubtedly many other hormones and enzymes, but I like what Richard Feinman says, 'Lower GI or lower fructose? How to do both without saying “low-carbohydrate” out loud? This tangled web is woven out of the failure to face scientific fact…'
    I seem to remember Gary Taubes saying something to the effect, 'A lot of science needs to be done yet, but in the meantime I'm probably going low carb.'
  6. chris c
    Also works in Type 2. I have probably never had a proper Phase 1 insulin response to food but can seemingly produce endless Phase 2 insulin, just not at a high rate. Also I used to have high IR yet without being overweight (not uncommon).

    My BG would shoot up on eating an appreciable quantity of carbs, then drop precipitously two to four hours later when the insulin failed to shut down properly. This causes carb cravings which are not only quantitatively but qualitatively different from "real hunger", and if ignored could actually cause me to fall over.

    For decades I "treated" this by eating carbs every couple of hours. The actual "cure" is to avoid the carbs, particularly at breakfast, avoid the BG spike and thus avoid the ensuing insulin spike and BG drop.

    Now I routinely go 5 - 8 hours and often ten or more hours without feeling any NEED to eat, then when the hunger does arrive it is genuine and not nearly so intense.

    Tell this to a dietician and they assume you are lying (with a few exceptions) and must be secretly eating three Weetabix.

  7. Amy
    I have had great success getting my own diabetes under control with LCHF and no medication. My FBGs are now consistently below 130 after only four months ( I still have much room for improvement ) My husband is also T2D and takes several medicines including insulin. Any time he tries to eat LCHF with me his blood sugar shoots up the next morning(FBG). I'm not sure what to do. He enjoys the food but is afraid to jump into it because of these spikes. Does anyone have suggestions? My theory is that his medication (he has not changed any dose) is causing the pendulum to swjng too far the other way...
  8. Amy
    I have had great success getting my own diabetes under control with LCHF and no medication. My FBGs are now consistently below 130 after only four months ( I still have much room for improvement ) My husband is also T2D and takes several medicines including insulin. Any time he tries to eat LCHF with me his blood sugar shoots up the next morning(FBG). I'm not sure what to do. He enjoys the food but is afraid to jump into it because of these spikes. Does anyone have suggestions? My theory is that his medication (he has not changed any dose) is causing the pendulum to swing too far the other way...
  9. Deborah Gordon
    Really nice summary. I remember years ago when Sunday meant orange juice, pancakes, syrup and eggs how badly I always felt about an hour later. I finally was able to actually check my sugar and it wasn't pathologically low, but I was quite sure that it had fallen from something high to make a blood sugar of 100 feel so bad!
  10. Jenx
    Why this persistent adversarial model...who's right and who's wrong? Does any mature individual who has done their best to absorb the evidence and has no dog or skin in the fight think its that simple? This site fractionates it a bit....who is More right. At its best that question is at the core of Empericism and science properly conducted.....except it's not WHO but WHAT is right.
  11. Jane Santos
    Stephanie Guyenet is not physics literate. She unfortunately cannot grasp that energy is not stuff, nor a thing , nor any kind of constituent that makes up the universe. Atoms, photons, fields are all stuff. Energy is strictly mathematical fiction, a number only. Energy is a property, a characteristic of OTHER ACTUAL STUFF-like atoms. Energy is not , itself, ANYTHING at all . Nor are its many many units anything at all. Calories are totally fictitious. Yes, you read that right. Energy is only a useful mathematical fiction. Joules, BTU, calories -no difference at all-all are units for measuring the exact same mathematical quantity, purely abstract math fiction. My sources are the late Nobel physicist, Richard Feynman, and currently Alan Guth.
    I wish Stephanie Guyenet educates herself.

    Take care,

    Reply: #13
  12. Chris
    How can your opinion be taken seriously "Diet Doctor" when you advocate low carb then encourage people to sign up to your program. Of course your opinion will be based on whatever gets people to join your program. Researchers like Kevin Hall and Stephan Guyenet are at least lead by the science and not their bank accounts. Taubes is another who has even admitted that he financially benefits from the low carb hypothesis.
    Reply: #18
  13. Chris
    You might want to educate yourself as well Jane. "Stephanie" is a male.
  14. Jane Santos
    Hall and Guyenet cannot grasp or understand energy. They both abuse and misuse it. I talked to Lev Okun, you fool. You need to educate yourself. Neither Guyenet, noir Hall have done ANYTHING to further advancement of understanding obesity. I personally know a Nobel prize winner in physics who thinks VERY HIGHLY of Taubes' health work.

    Look into Paul Lutus. Just because you have journals, wear white coats and oublish does NOT make you a scientist or investigator.

  15. Binky McGillicuddy
    I concur with Jane. Stephan Guyenet is way off base. This food reward stuff is nonsense. The overeating idea has been disproven.
  16. Gentiann
    I was reading an interview of Stephan Guyenet and I have to say that I was not impressed by his "food reward stuff" as Binky puts it......What I retained from it is that eating bland, boring foods that do not have salt or fat (so they do not taste very good) is going to make your brain tells you to stop eating because there is no pleasure eating that way......strange theory!
    LCHF does the opposite: eating delicious tasting foods (with fat and salt) makes your brain so happy that you are not hungry for many hours after a satisfying meal..... works better in my opinion that punishing your brain with bad tasting food.
  17. Jane Santos
    Guyenet is waaaay off base. He is a crank. There is no top obesity researcher claiming what he is-they all know simple overeating is NOT the cause of obesity-many normal people overeat-many obese people do not.

    Eating dull foods is pointless and will not solve anything. If anything, it WILL inspire BOTH normal people AND obese people to overeat. Plus, everybody -normal people and obese people alike will be chronically hungry.
    .Guyenet is a strange individual (and has a smug personality disorder) pushing a whackball discredited theory. Scientists already discredited overeating as the cause. Obesity is hellushly complicated and not 1/10th solved. REAL scientists , such as Dr. Friedman, know gene defects and mutations are involved in severe obesity. These people become obese irrespective of food intake (carbon atom ingestion)

    Taubes and Ludwig did fabulous work-the hormonal idea is one of the correct paths and fruitful. Insulin is important and I think it likely many more hormones must be studied and even discovered. Other paths are gene defects, potdntially gut flora and potentially toxins.

    Hall and Guyenet are wasting everybody's time.

  18. Tasha
    You've obviously not checked out Guyenet's web site then? He's pimping his own weight-loss program; and, no, it's not free.
  19. 1 comment removed
  20. John Kozinski
    If you read Stephan's book, he is basing his conclusions on science, research, and many culture's past eating. All the criticisms of his work that have been given are based on personal attacks. Gary Taube's cherry picks his evidence that supports his arguments. Emotions seem to drive these arguments rather than logic.
    Oddly, enough he like Ludwig doesn't recommend eating refined sugar or refined flour regularly for weight loss or overall health. Both are in agreement but just for different reasons.
    Cultures around the world stay thin eating diets their whole lives that are high in carbohydrates, low in fats, no refined sugars, not vegetarian, and eating mostly unprocessed whole foods.
    No cultures who had thinness and longevity ate diets high in fat ( or sugar).

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