Why Are We in Denial about Dieting?

The research is overwhelming. Diets don’t work long-term.

Posted Sep 11, 2018

Scientific findings on many topics can be muddled, confusing, or even contradictory. Nutrition science might have one of the worst track records in this respect. 

Drink wine. Don’t drink wine. Cut down on salt. Salt doesn’t matter. Avoid fats. Include fats. Eat many small meals throughout the day so that you’re not hungry. Go longer periods of time without eating even if you are hungry. Vitamins are essential. Vitamins do nothing but give you very expensive urine.

Even if you are highly motivated to take care of your health, it can be difficult to wade through all of these contradictory findings and recommendations. What many may not realize is that when it comes to one key topic in health and nutrition, the research has been so consistent that the conclusion is overwhelmingly clear.

Diets don’t work.

In the interest of good science, let me make that statement a bit more specific. The vast majority of dieters (regardless of the diet plan they’re following) do not maintain weight loss long-term (past one or two years).

Let the arguing begin!  Maybe you’re thinking, “My Aunt Sally lost 100 pounds doing Atkins!” Or maybe you remember that time you counted your food points and lost ten pounds. Or perhaps you’ve watched people shed weight on The Biggest Loser. (Long term outcomes of The Biggest Loser?  Not so good.)

 Lisa Fotios/Pexels
Source: Lisa Fotios/Pexels

There will always be exceptions to a general finding. But the overall conclusion is clear: in most cases, long-term diets tend to be ineffective. Most people who go on diets and lose weight end up gaining it back, dieting again, losing weight again, and gaining it back again. This pattern is referred to as weight-cycling. It’s a common outcome of dieting and has been linked with increased likelihood of weight gain over time, binge eating, and less consistent exercise. Additionally, weight cycling can contribute to cardiovascular risk. 

In 2017, the American Psychological Association put out a call for papers to be included in a special issue of Archives of Scientific Psychology on what they called “Heterodox Ideas in Psychology.” The idea was to curate a collection of papers on important findings that don’t get enough attention because they “run counter to conventional wisdom in the field.” The overwhelming failure of diets to achieve long-term weight loss was one of the findings addressed in this special issue

In the article on this topic, clinical psychologist Esther Rothblum reviewed evidence demonstrating that most people regain any weight they lose on a diet and between one-third and two-thirds of dieters end up weighing more than they did initially. The longer the follow-up period, the more dieters tend to regain. One of my colleagues who specializes in treating eating disorders put it this way: “Diets are a great way to gain weight.”

Even when results of large studies suggest successful weight loss, results are often skewed in favor of showing a diet worked because the researchers fail to take into account high rates of participant dropouts.  If a large portion of your study sample quits before the study is over, this is a hint that that diet is not realistic for many people.

The conclusion that diets don’t work is nothing new. In 2007, the American Psychologist published a review of research with the provocative title “Medicare’s Search for Effective Obesity Treatments: Diets are not the Answer.” Given that these research findings have been around for years, why do most people continue to believe that if they can just find the right diet, permanent weight loss awaits them? In part, these beliefs are the result of extraordinarily powerful marketing campaigns by the diet industry.  But they’re also a result of physicians and scientists who find it hard to accept the conclusions of research on this topic.

So, what should you do if you feel your weight is having a negative impact on your health? First, talk with your doctor (of course!). But also consider recent recommendations by the American Academy of pediatrics focusing on how to prevent teen obesity. The guidelines explicitly discourage dieting or focusing on weight.  Instead, the authors recommend focusing on eating healthy and being active as goals that can be endorsed independent of focusing on weight. Other researchers in this area suggest focusing on direct health indicators instead of weight. In other words, instead of making weight loss your key objective, you might work to improve your blood pressure or increase the activities you can comfortably engage in. If you happen to lose weight along the way, fine.  If you don’t, you can still improve your health.