The Evidence Against Dieting

The Evidence Against Dieting

Published on Monday, February 27, 2023 by Alexander Koch

Current US health statistics place 40% of the population as obese.


Obesity is considered a disease and has supplanted smoking as the #1 preventable cause of death.

Consequently, almost 50% of Americans are trying to lose weight on any given day.

Marketing diets to help one reduce their body weight is a huge industry, with an ever-growing series of books, seminars, apps, and online media to help people find the “secret” to help them lose weight. The real secret- there is no one secret!


Do Diets Work? Expectations versus Reality


Obese patients who attempt weight-reducing diets report a goal weight loss averaging 35% of their original body mass. For example, a 300-lb person would want to lose weight to achieve a new body mass of 195 lbs. Further, they report that any weight loss less than 17% of their original mass would be “disappointing”, and coupled with patients' own expectations, surveyed physicians report that any weight loss <13% of original body mass would be disappointing.  

The results of weight-loss attempts typically do not meet patients’ expectations.

The average weight loss after a year of dieting through commercial programs is about 5% of initial body mass. Extending diets for two years typically results in an additional 3% loss. So, after two years of sticking with a plan, dieters typically are quite far from their target body weight.

This mismatch between desired outcomes and actual results provides a recipe for disappointment on behalf of both patients and providers – a disappointment that could lead to despair and abandonment of even attempting healthy eating practices.

Weight regain occurs in about 50% of dieters without affecting lifestyle changes. There is even some preliminary research indicating the act of dieting can be a risk factor for long-term weight gain.

The addition of exercise in addition to dieting does not greatly accelerate weight loss either, sadly. Research indicates that accumulating between 150-250 min of moderate activity per week is only associated with modest weight loss.

On the bright side – losing 10% of one’s original body mass is associated with significant improvements in health, such as lowered blood pressure, improved blood cholesterol, and improved insulin sensitivity. The loss of 10% of one’s body mass is an achievable goal and meaningful goal, despite being lower than the expressed desire of most obese patients.   


Finding a Healthy Medium - that Works for You!


The statistics can look daunting. What can one do? 

Happily, we are all individuals, and data based on average outcomes does not absolutely apply to us. The key to achieving optimal health is to recognize what works for you on a behavioral level, a fact that researchers are beginning to prioritize in their quest to uncover the optimal obesity strategy. Adopting a lifestyle that gives you good health and psychological fulfillment is paramount to long-term success. 

Rather than “dieting”, by which I mean changing your eating behavior in a specific plan to achieve a goal of weight loss – you can be better served by finding high-fiber, low-calorie foods that you enjoy, and planning your meals around them. Focus on the addition of healthy foods to your meals rather than the deprivation of other higher-calorie offerings.

Exercise is important to overall health and weight maintenance. The key to successful exercise is to find ways to move that you personally enjoy. If your exercise bouts are as enjoyable as recess time when you were a kid, then it is a joy rather than a burden to move. Which is as it should be.

The average statistics on successful weight loss are daunting. Nonetheless, there are many success stories.

Drs. Rena Wing and James Hill created the National Weight Control Registry in 1994, to document the stories of people who have successfully lost an average of 66 pounds and kept that weight off for five years ( The 10,000+ people in the registry all found a way to maintain a healthy body mass that worked for them. You can too! 

  1. Barrea, L., Salzano, C., Pugliese, G., Laudisio, D., Frias-Toral, E., Savastano, S., Colao, A., & Muscogiuri, G. (2022). The challenge of weight loss maintenance in obesity: a review of the evidence on the best strategies available. International journal of food sciences and nutrition, 73(8), 1030–1046. 
  2. Centers for Disease Control. Obesity Data.  Accessed January 30, 2023.
  3. Centers for Disease Control. Accessed January 30, 2023
  4. Donnelly, J. E., Blair, S. N., Jakicic, J. M., Manore, M. M., Rankin, J. W., Smith, B. K., & American College of Sports Medicine (2009). American College of Sports Medicine Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. Medicine and science in sports and exercise, 41(2), 459–471.
  5. Foster, G. D., Wadden, T. A., Vogt, R. A., & Brewer, G. (1997). What is a reasonable weight loss? Patients' expectations and evaluations of obesity treatment outcomes. Journal of consulting and clinical psychology, 65(1), 79–85.
  6. Harris, B. H. L., Macaulay, V. M., Harris, D. A., Klenerman, P., Karpe, F., Lord, S. R., Harris, A. L., & Buffa, F. M. (2022). Obesity: a perfect storm for carcinogenesis. Cancer metastasis reviews, 41(3), 491–515.
  7. Haslam, D., Sattar, N., & Lean, M. (2006). ABC of obesity. Obesity--time to wake up. BMJ (Clinical research ed.), 333(7569), 640–642.
  8. Lytle, L. A., Nicastro, H. L., Roberts, S. B., Evans, M., Jakicic, J. M., Laposky, A. D., & Loria, C. M. (2018). Accumulating Data to Optimally Predict Obesity Treatment (ADOPT) Core Measures: Behavioral Domain. Obesity (Silver Spring, Md.), 26 Suppl 2(Suppl 2), S16–S24.
  9. Pélissier, L., Bagot, S., Miles-Chan, J. L., Pereira, B., Boirie, Y., Duclos, M., Dulloo, A., Isacco, L., & Thivel, D. (2023). Is dieting a risk for higher weight gain in normal-weight individual? A systematic review and meta-analysis. The British journal of nutrition, 1–44. Advance online publication.
  10. Tsai, A. G., & Wadden, T. A. (2005). Systematic review: an evaluation of major commercial weight loss programs in the United States. Annals of internal medicine, 142(1), 56–66. 

Leave a comment on this article: