How to fix your broken metabolism by doing the exact opposite


We saw recently with the Biggest Loser study that basal metabolism plummets when you lose weight with calorie reduction. As contestants lose weight, they burn a lot less energy – up to 800 calories per day less than before!

Some of that is expected, since there is less body tissue to maintain, but nevertheless, these contestants burn far less than expected even taking this into account. Even 6 years later, their basal metabolic rate (BMR) remains depressed, as do the contestants themselves.

The story got a lot of coverage, but one thing was consistently missing. How to fix it. That’s what I’ll show you today, and it’s the opposite of what most people expect.


So, let’s think about this problem in the context of the 2 compartment model of obesity that we have used before. There are two compartments for body energy. We take calories in as food. This gets stored in the short term as glycogen, or long term as body fat.

Glycogen is easily converted to energy (calories out), but body fat, not so much. So we can consider the analogous situation where short term energy is stored in a refrigerator and long term in the basement freezer.

NewHOT12Insulin’s role is to direct food into the basement freezer. When there is excess food that can’t be kept in the fridge, insulin directs it to the freezer.

This is body fat and manufactured in the liver by the process of de novo lipogenesis. What causes insulin levels to be elevated depends partly on the foods we eat, but also by insulin resistance.

Fructose, for example, plays a key role in elevating insulin resistance which will, in turn raise insulin levels. Insulin resistance leads to high insulin levels, which leads to higher resistance in a vicious cycle. That is, it can be self sustaining.

Read more in our guides what you need to know about insulin resistance and how to treat insulin resistance.

So during weight loss, if we don’t address the long term issue of insulin resistance, then some of the incoming energy is directed toward storage of fat. At the very least, we won’t be burning fat. Our basal metabolism gets energy from two sources – food, and stored food (fat). If high insulin levels blocks our access to fat stores, then almost all of our energy must come from food. If we reduce food intake from 2000 calories per day to 1200, in theory basal metabolism must also fall from 2000 calories to 1200.

This is a logical response from the body. Where would it get energy from? Fat stores are locked away since high insulin will block fat burning (lipolysis). So, as ‘Calories In’ goes down, so can ‘Calories Out’. This is why the Biggest Loser contestants metabolisms plunged so heavily. This is the problem of the solitary focus on caloric reduction. It may be about calories in, but it’s also about ‘Calories Out’.

Consider the analogy of soccer. Soccer’s First Law of Thermodynamics says that to win, you must have more ‘Goals In’ than ‘Goals Allowed’. Goals can’t be created out of thin air. So, therefore if we increase the numbers of ‘Goals In’, we will win every game. So, we move our goalie and position players all to forward and ask them to stay in the attacking zone.

Of course, we lose every single game. By trying to increase ‘Goals In’, we’ve increased ‘Goals Allowed’. The mistake is to assume that increasing ‘Goals In’ will not affect ‘Goals Allowed’. Then we blame players for not trying hard enough. But, in truth the strategy was bad.

Same goes for ‘Calories In’ and ‘Calories Out’. Reducing ‘Calories In’ can result in reduction of ‘Calories Out’. When this happens, you’ll lose every single time, as the Biggest Loser proves. The mistake is to assume that reducing ‘Calories In’ will not reduce ‘Calories Out’. But it does. Then we blame patients for not trying hard enough, but in reality, the strategy of ignoring insulin is bad.

How to Fix your Broken Metabolism

So, are we doomed to a life of ever growing waistlines? Hardly. Remember, the key to weight loss is to maintain energy expenditure (calories out). If you simply increase food intake again, you’ll simply increase weight. So, what to do?

2CompartFastingThere are two compartments here. The body will get energy from food, or stored food (fat). So one answer is to unlock the door which is preventing us from accessing our fat stores. It is the high insulin levels that is keeping all the energy locked away in fat. Insulin is blocking the door so that we can’t get to that basement freezer. Once we understand that, the solution is simple. We need to lower insulin. The key is to release all the pent-up energy stored in the body fat. The crucial junction in weight gain/loss may not be the calories, it’s likely the insulin because that is what opens up the door to release the fat for burning.

Lowering insulin will allow fat burning (lipolysis). This provides our body with lots of energy. If we have lots of energy coming in, the body has no reason to shut down its basal metabolism. The quickest, most efficient way to lower insulin? Fasting. Ketogenic diets will work, too. But remember that insulin has many inputs and is not simply carbohydrates. Cortisol, protein, fructose, insulin resistance, fibre, vinegar and countless other things play a role in determining insulin levels. Generally, though, cortisol and insulin resistance are the things least likely to be treated.

Once the doors to the ‘fat’ freezers are open, the body says, “Whoa, there’s lots of energy here. Let’s burn a little extra”. Studies of fasting show that basal metabolism doesn’t shut down during fasting, it revvs itself up. Four consecutive days of fasting increases basal metabolism by 13%.


Studies of alternate daily fasting (ADF) shows the same thing. Basal metabolism is maintained, even over 22 days of ADF. Even with weight steadily decreasing, the resting metabolic rate is statistically identical at the end of 22 days. You can see from the table below, that carbohydrate oxidation plummets as fat oxidation rises, just as seen previously.

This is an important point. In standard caloric reduction strategies, the body reduces its caloric expenditure to adjust to the reduced caloric intake. Stores of energy locked away as body fat are not available. If you reduce your calories from 2000 to 1200 per day, then your body may be forced to reduce calorie expenditure to 1200 per day since it cannot get any from the stored food (fat). Where’s the extra energy going to come from?

However, by lowering insulin drastically during fasting or alternate daily fasting, the body does not shut down. Instead, it switches fuel sources. No food in coming in. Insulin falls. Your body has a choice. It can reduce calorie expenditure to zero, also known technically as ‘dropping dead’. Or, it can force open the reserves and power itself from fat.TEE

TEELowering insulin makes it much easier to open up these stores of fat. That’s its normal job. When you eat, insulin goes up, fat goes into storage. When you don’t eat (fast), insulin goes down and fat comes out of storage. Dr. David Ludwig showed a similar result when comparing diets. In his study, he compared the total energy expenditure after weight loss with three different types of diets – low fat (standard advice), low glycemic index and very low carbohydrate.

The low fat diet does nothing to reduce insulin levels. So fat stores are blocked from being used for energy. Basal metabolism drops almost 400 calories per day. But on the other extreme, very low carbohydrate diets would be the diet that lowers insulin the most. This allows access to the basement fat ‘freezer’. Now our body has the energy it needs to start revving up its metabolism.


It works with surgically enforced fasting such as seen with bariatric surgery, too. The one contestant, Rudy Pauls, who got bariatric surgery fixed his wrecked metabolism. So, is it possible? Definitely. Rudy Paul’s metabolism had slowed more than any other contestant. That’s why his weight regain was so dramatic. By forcing himself to fast, he has partially repaired his broken metabolism.

In order to fix our broken metabolism, we need to allow free access to the energy contained within our fat stores. We need to allow fat burning (lipolysis) to proceed normally. We need to lower insulin. The answer is low carbohydrate diets, or even better – intermittent or extended fasting.

il_570xN.380160499_gd9jFasting maximally lowers insulin and ignite the flames of fat burning. Caloric reduction wrecked our metabolism by causing it to shut down. How to fix it? Do the exact opposite of what you expect. Push your caloric intake towards zero!

This is the George Costanza method. If everything you do makes things worse, do the exact opposite.

It does not matter if you think it doesn’t make sense. Do it anyway and see what happens.

The standard nutritional advice given – to Eat Less and Move More is so flawed that doing anything, even the exact opposite will likely beat it.

Try low carb

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


Try intermittent fasting

What is Fasting? – Dr. Jason Fung
How to Maximize Fat Burning – Dr. Jason Fung
How to Fast – The Different Options – Dr. Jason Fung


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
The Etiology of 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. Ellen
    If I'm fasting m, w, fri, can I eat a little bit of rice on the other days and still reduce my insulin resistance?
    Reply: #4
  2. Seth
    This is a great article -- possibly may favorite of Dr. Fung's so far! I have noticed that my metabolism is a bit lower than expected for someone of my age and size (based on online calculators). I had noticed that adding short fasts seemed to mitigate the difference somewhat, but hadn't been sure or understood why. Nice!

    As a side note, Dr. Tung offhandedly mentions vinegar as something that affects insulin levels -- a quick Google search suggests that it lowers insulin, which is consistent with my observation that a bit of vinegar in the morning keeps me from getting hungry while fasting. Another mystery solved. Thanks!

  3. 1 comment removed
  4. Geraldine Denise
    Why eat a high carb food if you want to lower your insulin resistance? Why not eat some Chia seeds, which swell, help your digestion and don't have many carbs after you deduct fiber!
  5. Mary
    Why the freaky man in the photo sprawled over the couch?
  6. Roxie C
    That is george costanza from Seinfeld, as metioned in the article. Lol
  7. Meg
    "Caloric reduction wrecked our metabolism by causing it to shut down. How to fix it? Do the exact opposite of what you expect. Push your caloric intake towards zero!"

    Isn't pushing the caloric intake toward zero the thing we don't want to do? Or am I completely confused?

    Reply: #20
  8. 1 comment removed
  9. Matt E.
    Hi Jason,

    Your comparing bariatric surgery to fasting caught my attention. People who have bariatric surgery are counseled to eat smaller portions, thereby reducing their daily caloric intake. The smaller stomach increases their satiety and helps keep them satisfied with fewer calories. I've never heard of a bariatric surgery patient being told to fast.

    It seems to me that weight loss following bariatric surgery should be considered evidence that calorie reduction causes weight loss. No?

    Reply: #17
  10. Matt E.
    Here's the Medline Patient Guide for Gastric Surgery. There is no talk of fasting, and the guidance models conventional calorie reduction advice.


    - Eat 6 small meals throughout the day instead of 3 big meals.
    - DO NOT snack between meals.

    Calories Still Count. Avoid foods that are high in calories. It is important to get all of the nutrition you need without eating too many calories.

    DO NOT eat foods that have a lot of fats, sugar, or carbohydrates.
    DO NOT drink much alcohol. Alcohol has a lot of calories, but it does not provide nutrition.
    DO NOT drink fluids that have a lot of calories. Avoid drinks that have sugar, fructose, or corn syrup in them.

    Portions and serving sizes still count. Your dietitian or nutritionist can give you suggested serving sizes of the foods in your diet.

    If you gain weight after gastric bypass surgery, ask yourself:

    Am I eating too many high-calorie foods or drinks?
    Am I getting enough protein?
    Am I eating too often?
    Am I exercising enough?

  11. Nick

    I am a big 6ft4 guy, 90kg, age 33

    I should have an RMR of around 2100cals.

    But I decided to get a TRUE result because I suspected it was low.

    I went to a lab where they measured it using the gold standard breathing apparatus to measure CO2 production while lying down for 25 minutes.

    My RMR is less than half : 1029cals !

    This is devastating. I have no idea how to fix this.

    I have high belly fat. Low muscle. High estrogen and have eaten paler style whole foods heathy diet for years.

    Please help - I don't know what to do.

    Also, none of the nutritionists and functional doctors have figured it out yet

    Any help welcome.


    Replies: #12, #18
  12. Yo
    Try fasting.
  13. michael
    What's the scientific definition of a fast ?
  14. Mia
    To lower estrogen take Myomin
    Dr Chi supplements
  15. Janette
    Hi Nick,
    I am so pleased that you asked that question. I would strongly suggest 'the obesity code' book. It is absolutely priceless and will change eat and your ability to successfully, permanently increase and reset your basal metabolic rate!.
  16. 1 comment removed
  17. Laura
    Hi Matt
    I had a bariatric surgery (gastric sleeve) and for the first 17 days I only drunk clear liquids, followed by two months of blended low carb high fat foods where I could bearly eat one spoon at a time and had them 4 to 6 times a day. Considering carbs and calories, this was almost three months fasting. Lost 100 pounds the first year and 5 years later I'm still on my ideal weight only following Keto.
  18. Laura
    Hi Nick!
    I hope you did the switch from paleo to Keto and increased your fats consumption right? how about HIIT? Fasting?
    Any news on the progress?
  19. June
    Seth ordinary vinegar is really bad fir raising suger levels hence affecting insulin, raw apple cider vinegar on the other hand is goid has a totally different affect on insulin levels
  20. Samuel Martinez
    As I understand it, eating a calorie-reduced version of a standard American diet damages your metabolism by partially reducing your dietary energy intake while keeping the energy of your fat stores locked behind insulin, so that your body slows down to run off less. Whereas fasting, because it lowers dietary energy intake to a level it's impossible to run off no matter how much you slow down, instead lowers your insulin and makes your stored energy accessible to your metabolism. The hope is that when you return to normal food intake, your metabolism retains access to your body fat and decides that it can afford to burn more energy and ask for less food.
  21. Pam
    My BF just started a low carb diet (less than 40g/day). Prior to that I tried to introduce him to IF, which he did until low carb and then it went out the window because he would rather eat when he feels hungry. But he also is over 150lbs overweight so he feels that it is fine if he is eating 500-1000 calories in processed foods a day a time or two a week because he "has enough fat stores"

    Is that true? If not, what is a good resource to show him? He won't listen to me that it doesn't sound healthy.

    Reply: #22
  22. Kristin Parker Team Diet Doctor

    My BF just started a low carb diet (less than 40g/day). Prior to that I tried to introduce him to IF, which he did until low carb and then it went out the window because he would rather eat when he feels hungry. But he also is over 150lbs overweight so he feels that it is fine if he is eating 500-1000 calories in processed foods a day a time or two a week because he "has enough fat stores"
    Is that true? If not, what is a good resource to show him? He won't listen to me that it doesn't sound healthy.

    We have a link here about foods to eat and foods to avoid that may address some of the food items you're talking about.

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