Long-term effects of dieting


Around and around we go…

Eat less; exercise more. I’ve said it myself, in print (sorry about that, guys). This weight-loss advice isn’t wrong exactly, but it’s terribly incomplete. The causes of obesity are complex, and a sudden worldwide epidemic of people lacking willpower is definitely not the answer.

When people go on a diet, they usually lose weight. And then, with the same predictability, over the next few years the vast majority of dieters gain it back. Most of us blame ourselves, without appreciating the powerful biology that underlies the process. Substantial weight loss increases hunger and reduces metabolism – meaning that a successful dieter must eat less (forever) than someone of the same weight who’s always been thin.

The data on long-term outcomes of dieting that I presented in my TEDGlobal talk come from this review article. On average, five years after a diet, most people were back to their original weight. A substantial minority, 41% of dieters, regained more weight than they had lost. And yes, those statistics probably apply to your favorite diet, whatever it is. None of the ones that have been studied have fared better than others in the long term.

In reality, the long-term outcomes are probably worse than that, because such studies are hard to do well. On average, researchers only managed to get follow-up data for a third of the participants after five years. As you might imagine, people who’ve kept the weight off are more likely to respond to such requests than people who’ve gained it all back and then added more pounds. Many studies asked participants to report their own height and weight, which most people underestimate. Finally, researchers often don’t take into account whether participants have been on other diets since the study began. Repeated dieting (weight cycling) can resemble successful weight-loss maintenance if you don’t look too closely.

Losing weight isn’t the hard part. Fighting your brain’s persistent attempts to make you gain it back is a much bigger challenge. And the costs of failure can be high. I’ll have more on that aspect tomorrow.

10 thoughts on “Long-term effects of dieting

  1. Hi Sandra
    I have searched for your Ted talk on dieting but can’t find the video – can you please let me know where I can find it – I read the Ted blog about it, but would love to use it in my teaching – I teach weight coach students and clients how to lose weight by paying attention to your body’s hunger signals, and about the dangers of dieting, and would love to share your talk with them.

    • Hello Sandra,
      I was lost until I watched your TED talk by accident. Thanks a lot!
      I just turned into 20 a couple of month ago but I wasn’t happy because of my weight problem. Just as you said, I’m one of those girls who started (intermittent) diet every young, around 15. And now I’ve gained all the weight back. I even suffered from Binge Eating Disorder because of my unwise dieting choice, which I only learned very recently. I couldn’t stop blaming myself.
      I want to put away of my weight problem but I don’t know where and how to start. Your person experience really inspired and encouraged me in a powerful way and I wish I could do the same. Now I live alone as a university student in a foreign country so I have to take care of myself. But now I don’t even know how to eat normally like ordinary people do. This may sound ridiculous but for a person under a strict diet for almost 3 years is really a painful thing to deal with.
      I want to end this badly and I do regret my unwise diet choice.
      I would be so glad if you can leave me any suggestions. 🙂
      Thank you.

      • If you want to learn more about mindful eating, there’s a new book out called “The Joy of Half a Cookie” by Jean Kristeller, which teaches a mindful eating program that’s been shown in clinical research to greatly reduce binge eating and help people form a better relationship with food. Or, if you can afford to consult a nutritionist, look for one who’s been trained in intuitive eating or health at every size approaches. Some of them offer online sessions, which you can do from anywhere. I hope you find an approach that works for you.

  2. My talk hasn’t been posted yet. It should go up on the TED website sometime in the fall or winter. I’ll let everyone know when it’s available.

  3. Pingback: The Science Behind Why Diets Don't Work | The DiehaRD Foodie

  4. I’ve read your statement about set point being a certain weight with a range of about 10-15 lb. Is that your opinion or has it been scientifically proven? Can you provide the reference regarding this stat? I’d like to learn more. Thank you.

  5. Hi Sandra! I wanted to know if could share your thoughts on “intermittent fasting”? When I did some brief research, I found a lot of it to make sense in developing an eating pattern that is realistic by not having to eliminate foods and focusing more on the “timing” of when to eat. I appreciate any insight you can shed on the topic!

    • As I’ve told other commenters, we don’t yet have good scientific evidence on intermittent fasting diets. The longest-term study of them that I’ve seen lasted only a year, which is the time of maximum weight loss for most diets, so there’s no reason to believe that this approach would be more effective than other diets in years 2-5, when regain normally occurs. I’m not optimistic, given that alternating fasting with feeding is a common way to produce binge eating in animal models. That’s more likely to lead to weight gain than weight loss in the long run.

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