Teen Dieting

A study led by Eric Stice at the University of Texas, Austin, found that ninth grade girls from California who were dieting or using more radical weight-loss techniques like laxatives, vomiting or appetite suppressants were actually more likely to gain weight over the course of four years than those who weren't trying to lose. "Most of us...think dieting is going to keep us thin," says Stice, "but there's never been a single study to date that has found that dieting as commonly practiced in the real world leads to weight loss."

New Study Looks at Youth

While other researchers have shown the link between dieting and weight gain in adults, Stice's study addresses a younger population that has seen dramatic increases in obesity in recent years.

According to the Center for Disease Control and Prevention, 11% of adolescent girls are currently overweight, up from just 6% in 1980. "This is a serious problem," says Thomas Wadden, director of the Weight and Eating Disorders Program at the University of Pennsylvania School of Medicine. "One of the things that's most worrisome is now if you have fatter adolescents you're going to have that many more fat adults."

But Wadden says that just because these girls got heavier by dieting doesn't prove that dieting causes them to get heavier. "In some cases dieting means intent to diet," he says, "but it does not necessarily mean that they are dieting."

Calorie Intake Critical

The girls, though they said they were trying to lose weight, may not have been eating fewer calories. Stice points to research by Janet Polivy, a psychologist at the University of Toronto, which shows that dieting often leads to binge eating. Stice favors an alternative explanation: girls who say they are dieting may be those who already have trouble maintaining their weight, either because of their genetic background or just a tendency to overeat.

The study produced one other surprising result. Girls who said they were trying to lose weight by exercising also gained weight. In contrast, most studies in adults have found that exercise is associated with weight loss and maintenance of that loss over the long term.

But Stice says the weight gain may be explained by the fact that exercise causes an increase in lean muscle mass, which is heavier than fat. "These findings show that there is a need for education in children about what is proper eating and proper exercise and a healthy lifestyle in general," says John Foreyt, director of the Nutrition Research Clinic at the Baylor College of Medicine in Houston. "I would advocate that people abandon an off-and-on dieting approach," says Stice, "where they overeat and then undereat to compensate and instead adopt a chronic healthy lifestyle.

It's a thing that you want to commit to for life rather than something you do to fit into a bikini this spring."