The Biggest Loser FAIL and that ketogenic study success


This week, splashed all over the New York Times, was an article about a paper written by Kevin Hall, a senior researcher at the National Institutes of Health. It was published in Obesity and titled “Persistent metabolic adaptation 6 years after ‘The Biggest Loser competition“. This generated a lot of hand-wringing about the futility of weight loss.

NYT: After ‘The Biggest Loser,’ Their Bodies Fought to Regain Weight

The study, along with another study presented by Kevin Hall seemed to generate more anxiety about the insulin hypothesis being dead. Of course, both these studies fit in perfectly with the hormonal view of obesity and reinforces once again the futility of following the Caloric Reduction as Primary approach. You could review my 50ish part series on Hormonal Obesity if you want a more in-depth view.

So, let’s dive in an explain the findings of both of Dr. Hall’s excellent papers. His conclusions, well, let’s just say I don’t agree with them. The studies, though, were very well done.

The Biggest Loser

Let’s start with the first paper about the Biggest Loser. Essentially, what it did was follow 14 of the 16 Biggest Loser contestants. At the end of the show, they had all lost significant amounts of weight following a Eat Less, Move More approach. Contestants eat about 1000 – 1200 calories per day and exercise like mad people.

What the study showed is that basal metabolism drops like a piano out of the Empire State building. It plummets. They are burning about 800 calories less per day than previously. The new paper shows that this metabolic rate does not recover even 6 years later.

In other words, if you reduce your ‘Calories In’, your ‘Calories Out’ will automatically drop. This makes sense. If your body normally eats 2000 calories per day and burns 2000, then what happens when you only eat 1200 calories? Let’s use the Socratic method and ask a related question.

If you normally earn $100,000 per year and spend $100,000, what happens when your income drops to $50,000? Well, you are not stupid and don’t want to end up in debtor’s jail, so your spending drops to $50,000. Well, our body is not stupid either. If we are eating 1200 calories, we automatically adjust by burning 1200 calories. The body does not want to die, and neither do I. Why would we assume the body still burns 2000 calories? It’s just not that stupid.

So, while we all obsess about reducing ‘Calories In’, it is actually virtually irrelevant for long term weight loss. It’s only ‘Calories Out’ that is important. If you can keep ‘Calories Out’ high, then you have a chance to lose weight. But Caloric Reduction as Primary (neatly abbreviated as CRaP), absolutely will not do it for you. This method is practically guaranteed to fail. This weight-loss method, in the literature, has a 99% failure rate. In this study, 13 of 14 Biggest Loser contestants failed – a 93% failure rate. Pretty much expected.

The Women’s Health Initiative study of 50,000 women proved this in 2006. Those women reduced their caloric intake by 350 or so calories per day. They expected to lose upwards of 30 pounds per year. Over 7 years, they lost …. 0.25 pounds! That’s like the weight of a good sized bowel movement, for goodness sake. Hmm. 7 years of Eat Less, Move More dieting or have a good BM? Same diff…

That reducing calories causes basal metabolism to plummet was already proven long ago in the 1950s by nutritional history’s favorite whipping boy, Dr. Ancel Key. His famous Minnesota Starvation Study was not actually a study about starvation. Subjects were put on roughly 1500 calories per day diet. This represented about a 30% reduction from their previous diet. They were also forced to walk about 20 miles per week. So, this was a Biggest Loser approach – Eat Less, Move More on steroids. What happened to their basal metabolism? They ate about 30% less, and their basal metabolism dropped about 30%. They felt cold, tired, hungry. As they ate, all their weight came right back.

This is what is sometimes termed ‘starvation mode’. This is what people imagine happens as their body starts to shut down in order to conserve energy. Basal metabolism (Calories Out) falls and you feel like crap. As you eat less, your body burns less calories, so that eventually weight loss plateaus. Then you feel like crap, so decide to eat a bit more (your hunger hormones are also rising like a spire), but not as much as you used to. But, your ‘Calories Out’ is so low that you get weight regain. Sound familiar? Happens to just about every dieter out there. What’s unfair is that their friends and family silently blame the victim of having ‘fallen off the wagon’, or not having enough will power. Actually, the dietary advice – Eat Less, Move More is the culprit. Blame it, not the victim.

So here’s what we’ve learned so far.

  1. Cutting calories puts you into starvation mode.
  2. The key to losing weight in the long term is maintaining basal metabolism, or keeping ‘Calories Out’ high.

We need to keep basal metabolism high. What doesn’t put you into starvation mode? Actual starvation! We see this effect with either studies of fasting, or studies of bariatric surgery.

So, what happens with bariatric surgery? This is also called stomach stapling. Because the stomach is the size of a walnut, people cannot eat. Their caloric intakes falls very close to zero. Fasting is the same except it is voluntary reduction of calories towards zero. What happens to basal metabolism? It is maintained! One of the Biggest Loser contestants in fact, did have bariatric surgery. What’s telling is that his metabolic rate started to go back up!

Let’s think about what is happening here (you may also want to refer to my 26ish post series on fasting). As you fast, there are a number of hormonal changes that do NOT happen with simple caloric reduction. Your body senses that you are getting no food. Growth hormone surges. Noradrenalin surges. Insulin drops. These are so called counter-regulatory hormones that are natural reactions to fasting. They keep blood glucose normal. Growth hormones maintain lean mass. Noradrenalin keeps basal metabolism high.

Studies of bariatric surgery show the same thing. Resting energy expenditure (calories out) is maintained despite severely restricted calories.

In 4 days of fasting, basal metabolism did not drop – instead, it is increased by 12%. Exercise capacity (measured by the VO2) is also maintained.

Let’s think about what is happening here. Imagine we are cavemen. It’s winter. We’ve eaten nothing for the past 4 days except for some yellow snow (ahh dang it…). If our bodies go into ‘starvation mode’, then we would be lethargic, tired, and cold. We would have no energy to go out and get food. Every day gets worse. Eventually we die. Nice. Why do we think our bodies are that stupid? I don’t want to die.

No, instead, what happens is that the body opens up its ample supply of stored food – body fat! Yeah! We keep basal metabolism high, and instead change fuel sources from food, to stored food (or body fat). Now we will have enough energy to go out there and hunt some woolly mammoth and beat up the guy who peed around the cave entrance.

There is no ‘starvation mode’ with actual starvation. As long as your body fat stays about 4%, you are fine. But don’t you burn protein? No, here’s what happens according to Dr. Hall’s own study of fasting.

You stop burning sugar (carbohydrates) and switch over to burning fat. Oh, hey, good news – there’s plenty of fat stored here. Burn, baby, burn.

In fact, there has been a direct comparison of bariatric surgery patients with Biggest Loser contestants. In the graph, you can see that metabolic rate was measured in Biggest Loser contestants (BLC). Their metabolic rate just keeps going down, down, downtown. That’s what the New York Times reported, too.

But look at the RYGB (Roux-en-Y bypass or bariatric) group. Their metabolic rate slows and then recovers. And that’s the difference between long-term weight loss, and a lifetime of despair.

The ketogenic diet study

In a related poster, Hall presents data on the ketogenic diet. He measured fat loss on patients in his metabolic ward. He used either a regular diet or a ketogenic (very low carbohydrate diet). He showed that the ketogenic diet lowered insulin levels, people burned fat (measured by fat oxidation) and people lost more weight. Great.

However, his fancy measurements of body fat also showed that the rate of body fat loss slowed down. So he said that this ‘proved’ that there is no metabolic advantage to ketogenic diets.

Nonsense. I have my doubts whether this DXA scan can actually detect the fractions of pounds of fat lost. Anyway, the main point is that people lost weight and were still losing fat. However, what he mentions in passing is far more interesting. He notes that the ketogenic diet did not produce any slowing of the metabolism.

That’s the gold medal, buddy!

Over 25 days or so, there is no slowing of metabolism??? That’s the most important part of long-term weight loss! That’s the knife edge between success and failure. The difference between tears of joy and tears of sorrow. In the Biggest Loser, contestants had dropped their basal metabolic rate by 500 calories per day. In the ketogenic diet, they are still burning the same amount – EVEN AS THEY ARE LOSING WEIGHT.

So, let’s recap:

  1. Cutting calories puts you into starvation mode.
  2. The key to losing weight in the long run is maintaining basal metabolism, or keeping ‘Calories Out’ high.
  3. Failure rate of Eat Less, Move More is around 99%. This remains the diet advice favored by most physicians and dieticians.
  4. Starvation (fasting or bariatric surgery) does not put you into starvation mode.
  5. Ketogenic diets do not put you into starvation mode.


For more on the ketogenic study and why it’s great news keep reading here:

The Calorie Theory of Obesity Falsified

Try it yourself

Do you want to try a low-carb and ketogenic diet yourself? Use these resources:



The Cause of Obesity and Diabetes – Gary Taubes
The Top 5 Tips For Weight Loss
Weight Control – A Question of Calories or Insulin? – Dr. Andreas Eenfeldt
The Key to Obesity – Dr. Jason Fung

More with Dr. Fung

Dr. Fung has his own blog at He is also active on Twitter.

His book The Obesity Code is available on Amazon.

The Obesity Code


  1. Gregory
    Using Keto/LCHF plus (intermittent) fasting keeps metabolism from falling. That is wonderful, paradigm-shifting information for new dieters.

    But what about people who have already slowed their metabolism through calorie restriction? What can they do to bring their metabolism up to higher levels, to lose weight or maintain it more easily without hunger? Will Keto/LCHF do this all by itself? How long might it take?

  2. Armin
    A study done with 14 participants is not a real study that can produce reliable statistical results. Also they base measurements on two different coloric measuring devices that have been proven to have a very high tolerances in reliability. Overall you can debunk the "study" just on these facts alone.

    No need to bring in the concept of hunger-mode, a myth that has been disproven for anyone who still has enough fat stored to have at least a normal bmi. Hunger mode is something you get if you are really deprived of nutrients for a long time - prisoners of war and the like.

  3. Kannadew
    I completely agree with Gregory's comment above!

    I lost 80kgs doing severe calorie restriction- almost Primal diet (w/ no exercise) and kept it off for about 3 years and it was VERY hard work... I have since then put on about 30+ kg over the last 2-3 years (8kgs of this in 4 weeks!- due to contraception), which seems to be a combination of stress, hormones and lack of exercise.

    I completely believe that I have stuffed up my metabolism and have tried paleo, low carb, etc... and still nothing seems to work. I have played around at "trying" Keto.. but my weight always seems to go UP and UP and I just get too scared and stop because I absolutely feel like my weight is going to skyrocket as it already seems to have done.

    I guess I want to "know" that if I give KETO a good hard try that it will not backfire because I have already messed up my metabolism?

    Hi Jason ,love your passion ! Could it be possible for you and Andreas to conduct an informal meta study of people who have followed low carb on both sites. By now there should be enough testimonials over time that could be followed up to reveal some tangible result on the effectiveness of low carb and/or fasting.
  5. Andrea
    Fantastic article! I've been waiting for diet to release a post responding to Kevin Hall's studies, and you did not disappoint!
  6. Alistair
    Brilliant post! Please can we have more of these in-depth posts.
  7. tz
    Kannadew - Try the 2 week low carb challenge but do it seriously. NO calorie restriction, stuff yourself with fatty foods when you feel hungry - butter, eggs, pork rinds, or whatever you like eating that has no carbs. (You need to throw the carbs out so you can't be tempted). But also check your medication. (Contraception, try "Natural Family Planning", it isn't just the Rythm method and keeps your body natural). One other thing, check "microbiome" - your gut flora. The "good bacteria". If that's out of balance it can cause problems, often curable with a little yogurt with active cultures.

    Another Low-Carb advocate :

    But I think a big area of undone research is the starvation effect. 2000 in and out, but with carbs makes you or keeps you fat. Cutting to 1200 in makes you feel horribly sick and weak and your body switches to 800 out, so you can actually gain weight (and where do you get nutrients if you aren't eating). I'm mostly sedentary. I lost the weight, but when my appetite disappeared I stopped eating. I'm probably 1200 in and out. If I exercise more I get more hungry. If I rest, less.

    And the above brings up another good point. Too many are on some kind of drug, contraception is a very common one but how does it affect your body in all the other ways. Then there's things to keep your digestive system calm (why is it having problems digesting?), we already know about statins, and I forget the half dozen advertised on TV over the last hour. We treat symptoms, not root causes, then we treat the side-effects in an every growing pharma-pyramid.

    I have rarely taken any prescriptions (I can feel my body is off, strange, wrong), but what was missing was eating real food. Although Karl Denninger above is on factory food, he still has lots of real food. I'm now in a rural area so I can get grass-fed beef, raw milk, free range eggs and chicken, and more. All the nutrients are there. I'm eating even less and feeling even better, and the factory food now tastes like plastic.

    The double whammy is not only is it high-carb, but highly processed. White flour with high-fructose sugar but no nutrients. I found I could eat Einkorn in moderation (e.g. butter soaked french toast) without ill effect, but equally a small plate of pasta or scoop of ice-cream causes a bad reaction now. Orange juice is not Oranges, and the original plants aren't those bred to have excess sugar and starch (without any more vitamins, minerals, or proteins). Historically, when people did a lot more, they ate some of these fruits and grains, but they were more nutrient dense.

    I think we are returning to nature and treating our bodies not like something in the liquid like in "The Matrix" but remembering our true natures and what we ate originally, and how our bodies are adapted to that.

    But there's one last point to the carb/starvation. Before preservation and agriculture, many foods were only in season for a short time, and we can handle sugars and starches. I suspect that when the fields were white with lots of starch, or the trees with lots of sugars the optimal behavior was to binge and store those calories as many pounds of fat - typically harvest time in the Autumn. But then Winter would come with intermittent hunting of meat, but a lot of cold where we would be designed to burn off those fat calories while trying to not shiver. What changed is it is not a perpetual Autumn where the addictive foods are available every day and that even in the coldest winters, most people have their thermostats at 72F (I tend to keep mine at 50F - unless I'm sick or something I don't feel cold.). So the first frost and the cold that encourages brown fat never comes.

    Reply: #10
  8. Kristin Noll-Marsh
    "He notes that the ketogenic diet did not produce any slowing of the metabolism."

    Dr. Fung, could you please point me to where he notes this? I've read the transcript of his video and couldn't find where he makes that observation? That's a huge detail that I'd like to be able to point out!

    Reply: #9
  9. MJ
    Look at the charts.
    Energy expenditure both awake and asleep went up on ketogenic diet.
  10. Kannadew
    TZ- Thanks so much for your suggestions. I agree... I just need to give it a go for 2 weeks and see what happens. Thankfully Im no longer on any contraception, having gone for a tubal ligation, but that too completely messed up the hormones. 2 weeks is not a long time... just need to prepare as you said. Thanks again.
  11. Richard Bennett
    Kevin Hall's two studies falsify the carbohydrate/insulin hypothesis. This post is the equivalent of climate change denialism. Gotta protect those book sales, apparently.
  12. Tim L
    I am currently doing intermittent fasting 5 or 6 days a week (I just started week4). I typically eat one low carb meal in the evening. I am sure my overall calories are lower than in the past. Will I be damaging my metabolism with the way I am approaching this? Thanks
  13. Hazel
    I've just read Dr. Fung's THE OBESITY CODE, a very good read, and wish I had had all this information 7 years ago when I began using PROTEIN POWER to lose weight/regain my health.
    Everything would have been so much clearer, and easier. But never mind, I persisted, while reading everything I could find about what eventually began to be identified as LCHF, and I've done very well using little adjustments that I found by reading blogs and books. Late last summer, using an article at this website, I began a version of intermittent fasting (I fast for 3/4 of the day and only eat one meal per day during the remaining 4 hours). The second day I fasted something amazing happened to my metabolism and I felt wonderful. I had no hunger during fasting hours, the remaining body fat I had been worrying about disappeared, I dropped one full size in my jeans, and I had notably more energy. Now, nearly one year in, my weight is down 65# from my original starting point, I have energy to spare and my health is better than it's ever been.
    For anyone who has fears of starting LCHF/intermittent fasting should try it for a couple of weeks. Keeping carbs down to less than 20 grams per day was the tipping point for me. Feeling completely well is what confirms to me that I'm one of the people who only does well on very low carb. Everyone's different, yes, but for those who need this program, don't hesitate.
  14. Jannu Jokunen
    Keto diets are unnecessary. There are no actual weight loss benefit from them.

    Effects of Low-Carbohydrate Diets Versus Low-Fat Diets on Metabolic Risk Factors: A Meta-Analysis of Randomized Controlled Clinical Trials

    "In the present meta-analysis of randomized controlled trials comparing low-carbohydrate diets with low-fat diets, we found that both diets were equally effective at reducing body weight and waist circumference."

    What people need, is a diet they can actually maintain. And keto is so ridiculously unnecessary extreme, that it does not work. It comes with a long list of side effects.

    What people need, is a healthy diet that can be maintained for long term:

    A randomised controlled trial using a whole food plant-based diet in the community for obesity, ischaemic heart disease or diabetes

    "To the best of our knowledge, this research has achieved greater weight loss at 6 and 12 months than any other trial that does not limit energy intake
    or mandate regular exercise."

    Reply: #20
  15. Matt
    Truly, truly misleading article.
    Reply: #19
  16. Grace Sanchez
    I started LCHF in July 2018 & have lost 55 lbs & have completely reversed my type 2 diabetes. My A1c was 6.8 & now is 5.2. Anyone who says they are doing the keto diet & not losing weight must be doing something wrong. You need to check the 5 biggest mistakes people make on keto & see if you are guilty of any of those mistakes.
  17. Bruce Witte
    I will be 60 this summer. I weighed 440lbs on April 1st 2017 currently I weigh 290. Binge eating has stopped. My cholesterol decreased from 160 to 116. My fasting BS decreased from 118 to 92. My exercise ability has increased 10 fold. I do IF 18:6. I’m hoping to be at 220 lbs by October but if not thank God I’m not bingeing!!!
  18. William
    For weight loss aren't we told on Keto to restrict calories (carbs AND dietary fat) and to create a deficit from our normal BMR values? I'm having a hard time understanding the distinction between this 'keto' type of caloric restriction and starvation mode caloric restriction common in most other diets? Is it because they also restrict protein?
  19. Steven
    @Matt Truly, truly unhelpful comment.
  20. Steven
    @Jannu You don't seem to understand the effects of longterm calorie reduction. It lowers the basal metabolic rate.
  21. Bob
    "If you normally earn $100,000 per year and spend $100,000, what happens when your income drops to $50,000? Well, you are not stupid and don’t want to end up in debtor’s jail, so your spending drops to $50,000."

    Using your analogy, does going on a Keto diet mean that when earning only $20,000 you can magically keep spending $100,000?

    Reply: #23
  22. Rohde
    It more means that if you eat carbs consistently, you will be a "carb burner" and likely carry glycogen stores, if your glycogen is partly full but deprived your body feels deprived and slows down. If you stay deprived long enough your glycogen stays empty through low carb/ or keto/ or fasting and the body is forced to become a "fat burner" and you gain access to millions of calories of fat, body doesn't feel deprived hence doesnt slow down. You don't need keto, you just need to empty and stay empty on glycogen a good amount of time to access your fat. Keto mimics fasting, but you can fast to mimic fasting too :) Thats why IF works. We simply eat too often too many carbs, the insulin theory holds water. In the middle of writing a book on the subject, to be out soon!
    Reply: #25
  23. Katharina
    If your have $80,000 on your bank account and only earn $20,000, than you can still spend $100,000.
    Like when you have enough fat in your body, you can use that a s fuel.
  24. Emely Stayson
  25. Chris
    Rohde you summed it up perfectly. A year or so back i was running and running and exercising like crazy and not really losing weight because my diet had too many carbs and i was addicted to sugar soft drinks aka "MT. Dew". All that exercise and no results. I knew all along that it was because of the added sugar, i just wasn't educated nor mindful of how much i was taking in or how much the liver could bind up and store all that glucose as glycogen. I'd go out and run and run and it would drain some of my liver's reserves but when i got home i would drink soda which would replenish what i had burned off and therefore i never got to burning fat or losing any weight because of that reserve. Now that i've kicked my addiction to sugar sodas (actually harder than when i stopped smoking, to me anyways), I've lost more weight in one month than six months exercising from the spring to fall down in the hot southern climate. I feel a lot better too actually.
  26. Alexa
    So then because we have excess of fat to burn (if we have above 4% fat) our body doesn't drop lower our metabolism because it doesn't foresee a possible famine. We can eat much less and it still knows there's an abundance of fuel so no need to slow anything down? This is what I was thinking before reading this. It would make no sense for people on keto with much lower appetites to need to eat more to keep their metabolism up when they have ample reserves of fuel. This also makes sense to me from the perspective of why your appetite would drop in ketosis. When you think of it, the body would keep telling you to eat and sending hunger signals if it's sustaining on carbs because there are no backup stores. That's the body being smart. But if you have a reserve of fat that the body understands will meet its requirements for a long time to come, appetite would naturally reduce as the body knows you don't have to keep eating. You have more than enough. And so your hunger/appetite reduces. You don't have cravings. Your body keeps burning all those stores of fat with no worry about there not being enough. That is a perfectly sensible system. And it seems it's the one way to reduce calories and not experience metabolic slowing.
  27. Iga
    HEALTHY Keto (with 10 cups of leafy greens and only quality keto food a day) diet changed my life. Healed my body and mind! It massively improved my 74 year old mum's Parkinson's disease and helped me loose 10 kg I was struggling with since my teenage years.
    Whoever doubts it's power never tried it and is simply prejudiced. That's my opinion.

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