The Truth You Don't Want to Hear About Going on a Diet

It's probably making you gain weight.


Years ago, I visited friends who were worried about their much-loved teenage daughter. She had started gaining weight at puberty, and her parents couldn't figure out what to do. They tried talking to her about portion control and exercise. They tried cooking her special food. Nothing slowed her progression from skinny child to curvy woman. Everyone in the family had always been thin, so her parents didn't think to ask whether her weight gain was a medical problem (it wasn't) or just the natural result of her having a different body type from the rest of them.

As a neuroscientist, I knew the research suggested that her parents' well-meaning anxiety was probably making matters worse for the girl. She was reluctant to sit down for meals with the family and ate almost nothing when she did. But her father said food was disappearing from the refrigerator overnight, and her weight gain continued. She appeared to be on her way to developing an eating disorder.

I understood her struggles because I was that teenage girl myself once. As an awkward and self-conscious (though actually normal-looking) young teenager, I was convinced that I needed to change almost everything about my body before I could fit in.

The author at age 13.
Courtesy of Sandra Aamodt

When I was 13, my mother suggested I start watching my weight, so I went on my first diet. I used the money from my paper route to buy salad and cantaloupes, which I kept in the basement to avoid being tempted by everyone else's food. I'm not sure how I set my goal of 800 calories a day, perhaps from a magazine or other girls at school. I certainly didn't know that amount of food was less than half the energy my body needed — or that my brain would push me to regain the weight over time.

Through my teens and 20s, I lost the same 10 or 15 pounds almost every year. Lots of my friends were doing the same thing, so dieting just seemed like something women did. When I was heavier, I tried to ignore and hide my body. When I was thinner, I felt proud but also hungry. Either way, I couldn't relax about my weight.


As the research would predict, repeated dieting eventually caught up with me. I started binge-eating in my mid-20s during a stressful period. I would finish a carton of ice cream or a box of saltines with butter, usually at 3 a.m. when I couldn't sleep. Even after I had made myself sick, I would keep eating. I gained 20 pounds that year, and I was lucky to be able to quit binge-eating without help when my stress levels dropped.

Pressure to be thin has strong effects on children — but not the ones most parents intend. Predictably, when you worry about weight, have a history of dieting, and even family members who tease kids about being chubby, you can expect future weight gain and eating disorders. A long-running study called Project EAT found that girls who repeatedly dieted or whose families made fun of their weight gained twice as much during the next 10 years as other girls, whether or not they were overweight initially. Another study found that girls who dieted frequently in early adolescence were almost five times more likely to move from normal weight to overweight over the next two years. Thin Norwegian teenagers who felt they were overweight gained more weight in the next 11 years than their peers who correctly believed their weight was fine. Finally, parents advising their daughters to diet at age 9 predicted greater weight gain by age 15, but only in the girls who did diet.

These studies also showed that weight-based teasing and frequent dieting greatly increase the risk of binge-eating, which may help to explain the weight gain. Teasing nearly doubled the risk of increased binge-eating among girls in Project EAT. Girls in the second study who dieted frequently were 12 times more likely to report binge-eating, while boys who dieted frequently were seven times more likely to binge-eat. A study of girls in northern California found similar results.

Overall, 35 percent of dieters develop pathological dieting, and 20 to 25 percent of pathological dieters progress to disordered eating. To break this cycle, Dr. Eric Stice, Ph.D, and his colleagues created the Body Project, an intervention to reduce the risk of future eating disorders in at-risk teenagers. Young women who are unhappy with their bodies are asked to make arguments against the importance of thinness, such as generating a list of the top 10 ways girls can challenge the thin ideal. Writing an essay about the costs of dieting led them to think about problems like not being able to eat with their friends at parties. By presenting these arguments to the group, the girls find themselves making a case against their own beliefs. Surprisingly, people in this sort of situation often react by changing their beliefs, in this case by deciding that being thin is not so important after all. That is, we figure out who we are by watching what we do, instead of the other way around.

The program works. In a randomized trial in high school girls who didn't like their bodies, program participants had a 60 percent lower risk of disordered eating three years later compared with their peers who completed an expressive-writing program. An online version also reduced the risk of eating disorders (though less effectively) and also eliminated the weight gain that occurred over the next two years in a control group of girls, who read a brochure or watched a documentary on eating disorders. That result reinforces the lesson that pressure to be thin increases the odds of both eating disorders and weight gain in the long run. 

With the help of a good therapist, our friends' daughter found a better way to relate to food and maintain her weight, through regular exercise and healthy eating without restriction. Her parents also got over their anxiety about her body. If we all did that, the research suggests we'd end up happier, healthier, and probably thinner too.

Sandra Aamodt is a neuroscientist and the author of Why Diets Make Us Fat: The Unintended Consequences of Our Obsession With Weight Loss.

Advertisement - Continue Reading Below
More From Health & Fitness