Why it’s so hard to lose excess weight and keep it off: The Biggest Losers’ experience

Robert H. Shmerling, MD

Senior Faculty Editor, Harvard Health Publishing

Follow me on Twitter @RobShmerling

For most people trying to lose weight, it’s a struggle. It takes more than good intentions and a lot of will power. One reason is that in order to lose weight, we are, in a way, fighting our own biology.

As we lose weight, the body adapts to resist it by lowering the resting metabolic rate — that’s the amount of energy spent while at rest, when the “engine” of the body is idling. Lowering the resting metabolic rate is a good thing if food is scarce and weight loss is occurring due to starvation. In that situation, it’s good that the body slows down to conserve energy and limit further weight loss.

But this evolutionary adaptation works against you if you are overweight or obese, and excess weight is a bigger threat to your health than starvation.

The experience of The Biggest Loser

Researchers have studied weight loss for decades to determine how the body responds to it. Among them are studies that enrolled participants in the television series The Biggest Loser. If you aren’t familiar with it, The Biggest Loser is a reality television series in which obese individuals compete to lose the most weight through an intensive program of exercise and dietary changes. A prior study found that after losing lots of weight, participants in The Biggest Loser had markedly reduced metabolic rates. But it was unclear how long those changes would last or whether they predicted regain of weight once the competition ended.

A new study of The Biggest Loser

A recent study looked at how participants in The Biggest Loser fared six years after their 30-week competition. Researchers publishing in the medical journal Obesity found that:

  • At the end of the competition, average weight loss was nearly 128 pounds. Since the average starting weight was about 327 pounds, that’s a drop of nearly 40% of body weight.
  • On average, participants experienced a 23% drop in their resting metabolic rate.
  • Six years later, competitors regained an average of 90 pounds, but the significant slowing in metabolic rate persisted.
  • There was not a direct correlation between the amount of metabolic slowing and the amount of weight lost during the show. However, after six years those who kept the most weight off had the most slowing.

These findings confirm that weight loss may lead to significant changes in metabolism that, in turn, resist further weight loss. In addition, keeping weight off may be especially difficult because those changes persist over time. The metabolic slowing that accompanies weight loss varies, however, so it may create less resistance to weight loss for some than others.

Now what?

The findings of this research may seem discouraging if you’re trying to lose weight.

On the other hand, maybe it should provide a measure of relief to know that the reason losing weight seems like an uphill battle is that it is! It’s not just that you aren’t trying hard enough —your efforts to lose weight are being actively undermined by biological adaptations of your body that developed centuries ago during evolution and are now hardwired into your DNA.

You might wonder: is there a diet, an exercise program, or a medication that can “reset” your metabolic rate or avoid its slowing during weight loss? In fact, you may have seen books or advertisements for certain diets or supplements claiming to do just this. Unfortunately, most have little convincing long-term evidence to back them up, or the changes are too small to matter much.

The bottom line

Knowing about the adaptations your body makes during weight loss and how that can frustrate your efforts to lose weight may make the effort seem futile. But it’s not. Determination, perseverance, and a sustainable plan are good first steps. It also helps to know what you’re up against. Contestants on The Biggest Loser know that well.

Related Information: Lose Weight and Keep It Off


  1. Julie

    Agree that deprivation in dieting does not work. A good way to go is to eat healthy meals at regular times throughout the day. A lot of folks tend to crave unhealthy snacks more at the end of the day. having a decent, healthy meal at 4 o’clock and a good dinner at 7:30 workS for this. And healthy food doesn’t have to be expensive. For instance, a bag of frozen berries at my local store cost the same as an icecream or a bag of cookies. I also think it’s counterproductive and a waste of energy to weigh yourself constantly. Much more important is to figure out what you need to feel healthy and how different foods affect your energy levels.

  2. Mandy Carrreno

    I understand from what I’ve read lately, that we are all in the same boat. We have within us DNA a gene which tells us we are hungry. Some of us never get that signal that we are hungry or that we have had enough. They now have a way to turn off the gene, but I wonder what good would that do, if we who have no way of knowing if we are really hungry or not continue to gain weight. Will
    they who may have this gene removed or altered gain more weight? Does anyone know? Thanks… : )

  3. Richard Ross - London

    Socrates said ‘nothing in excess’ which is what these extreme diets offer.
    A long slow change in eating habits works, but most people don’t have the determination to run the course. The less sugar intake, the less the craving and eventually the better the outcome.
    Keep away form crisps and all day snacking and have the occasional treat, shared with someone so you only half sin!
    Most people lack long term determination, so what is needed is research to find how to create the resolve to achieve the desired weight loss, long term.

  4. Madhur Kotharay

    As you lose weight, presumably fat, the fat cells secrete less leptin which is a hunger inhibition hormone.

    Your brain is used to certain level of leptin and low levels of leptin makes you feel more hungry.

    Also, just as in Diabetes, you develop insulin resistance, in obesity you develop leptin resistance.

    The good news is latest research shows that if you lose weight, and keep it down somehow for 14 months on an average, your brain gets used to the new levels of leptin.

  5. Venu Adhiya Hirani

    What about the effect of physical activity and focused increase in lean body mass? Won’t that counter the effect of lowered metabolism?

  6. Fiona Cosgrove

    We have to accept that it’s the go slow approach that will rep-set metabolism.. I love Dr. Amanda Sainsbury-Salis’ approach in her book, the “Don’t go hungry Diet”..

  7. Charlie Dannelly

    I am a personal trainer in Los Angeles of over 30 years. I had the privilege of working with a few of the BL contestants after they were eliminated from the show. They where given another chance to win if they lost more overall then the other eliminated contestants. On the show, the highest weight loss wins. So that means not gaining muscle mass as well. I think you know where i’m going with this. Low muscle mass + Low metabolism= Body fat gain. The body needs a reason to burn more energy and muscle mass is the only natural way. In closing I would say that the info on the metabolism after massive weight loss is good intel but the mindset after the weight loss is crucial! If your mind isn’t completely reset the right way then a relapse is certain. For more info on how I reset my clients mindsets check out the intel here. http://powerofthefitnessmind.com/

  8. bob choi

    How about people in Ethiopia? How can they stay so skinny?

  9. marvin

    why doesnt the authors reply to questions in comments to article .
    many good comments .,deserve a medical reply

  10. Veronica

    The only reason why people gain weight after they lose some pounds is because they return to their bad habits. They don’t understand that exercising and eating healthy is the right way to live forever not only to lose weight.

    • Lisa M.

      The whole POINT of this article, is proving it, in FACT, is NOT simply returning to bad habits, but the changes set off in their metabolism FROM DIETING that causes PERMANENT slowing of the metabolism! QUOTE
      “Six years later, competitors regained an average of 90 pounds, but the significant slowing in metabolic rate persisted.
      There was not a direct correlation between the amount of metabolic slowing and the amount of weight lost during the show. However, after six years those who kept the most weight off had the most slowing.
      These findings confirm that weight loss may lead to significant changes in metabolism that, in turn, “RESIST FURTHER WEIGHT LOSS”. In addition, keeping weight off may be especially difficult “BECAUSE THESE CHANGES PERSIST OVER TIME”. The metabolic slowing that accompanies weight loss varies, however, so it may create less resistance to weight loss for some than others.

  11. Mary

    This is the old “set Point” theory. Anyone who has tried to lose weight throughout life knows that the biggest loser was just reality TV gone wrong for dieters. Of course they would gain it back after they left the boot camp mentality and tried to re-integrate into their lives. It just did what most weight-loss fads do, make money for the promoters. Please look into sane ways to be healthy like eating healthy, living balanced, and getting help for stressors. Many people use 12-step OA, dieticians, licensed counselors, healthy exercise. Other research indicates that adipose tissue is metabolically active and tends to send out starvation signals with significant weight loss. And bariatric surgery is not for everyone, either.

  12. Cora Rubenstein

    What if they lost the weight slowly?

    How does this apply to a person, who at age 64, weighing 142 pounds, lost 30 pounds in 6months?

  13. Martha

    This article addresses lowered metabolism after extreme weight loss over a very short period of time. The question I have is, are the results the same for people who lose weight more slowly? Seems like that would be important information to know.

  14. David Bulkley

    Are there any studies on the effects of fasting one day a week? I have done this at different times during my life for extended periods, and have found that this is the best way to keep a steady healthy weight. The fast is water only or perhaps a small amount of juice with water, starting after dinner on one day, not eating the following day, and breaking the fast with breakfast. The fast lasts about 36 hours. My sense is that fasting only one day per week does not reset my body’s metabolism, so that my body still burns fuel at the same rate. I am reducing my food consumption by one seventh and am not restricting my diet on days that I eat.

  15. M Huffman

    Evolution seems to always be the answer when there isn’t an answer…. and in my humble opinion is certainly a stretch in this case….

    Ask scientists such as Dr. Brad Harrub of Focus Press..

  16. Merijane McTalley

    As a registered dietitian, I see this daily. I even see it in myself. I did the 23 and me DNA test and YES, it is genetic but not 300 lbs worth.
    Deprivation in dieting doesn’t work. I believe in eating anything you want, but in smaller portions. If I say to a patient, ” you can never have cheesecake”. We won’t be successful. That method doesn’t work.
    It is discouraging. So many give up and go the surgical route and graze all day and gain it back.
    I believe, that the new MINDFUL EATING trend may hold some hope.

  17. bob barnes


    So does diet and exercise still count as a means of weight loss?

    Can I resolve the effects of lower metabolism with a proactive diet and exercize program?

  18. AF Leger

    Found that change of diet, without wheat products, sugar, cakes , allowed one to drop 17 kgs, sustained after 6 years,

    limited exercise: about 4 hours fast walking a week,
    The Mediterranean regime mainly , with limited wine and lots of olive oil –
    no other restrictions or privation

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