Television, movies, magazines and other popular media often get blamed for pressuring teen girls to try to be as thin as models. But a new study finds that peer pressure also plays a strong role in how adolescent girls control their figures.

This isn't the first time that peer pressure has been fingered as a factor in risky teen behavior. Other studies have found that the cliques teens identify with can affect whether they smoke cigarettes, drink alcohol or take drugs. It now appears that similar identification carries weight when it comes to body image, food and physical activity.

"Teen girls' concerns about their own weight, about how they appear to others and their perceptions that their peers want them to be thin, are significantly related to weight-control behavior," says psychologist Eleanor Mackey of the Children's National Medical Center in Washington, D.C., and lead author of the study. "Those are really important."

Estimates are that about 5 percent of American teens suffer from eating disorders, including anorexia nervosa and bulimia. A study published last month in the Archives of Pediatric and Adolescent Medicine found that 10 percent of teen girls and about 3 percent of teen boys binge eat at least once a week.

At the same time, about a third of adolescents are overweight, while about 16 percent are obese, according to the federal Centers for Disease Control and Prevention. Those added pounds place them at increased risk for a host of health problems, from type 2 diabetes and high blood pressure to heart disease.

To measure the role of peer pressure on eating and exercise habits, Mackey and her co-author, Annette La Greca of the University of Miami, studied 236 girls from public high schools in southeast Florida. Participants ranged in age from 13 to 18. About a third of teens were white, another third were Hispanic or Latino and roughly 20 percent were black. The remainder were of mixed ethnicity.

Those who completed questionnaires noted their identification with various teen groups, including so-called "populars" (those who are outgoing and social), "brains" (teens who enjoy school and do well academically), "burnouts" (adolescents who often get into trouble), "jocks" (those who engage in sports) and "alternatives" (teens who rebel against mainstream culture in their appearance and attitudes).

Participants answered questions about body image and weight control, as well as how others appraised their appearance. A 2007 study by the same researchers found that teens most likely to identify with the burnout group had the worst eating, exercise and weight-control behavior. So-called "brains" had the best eating and workout regimens, although they also reported more dieting than other teens. Jocks and populars didn't always eat healthfully, but were the most likely to get plenty of exercise and to engage in more organized physical activities than other groups.

The latest study found that:

• Girls who identified with the alternative and burnout peer groups were the most worried about their weight and reported taking more steps than other groups to control it.

• Participants with a higher body mass index were also more concerned with their weight and perceived their peers to be more concerned with weight than were their thinner counterparts. They also reported engaging in more dieting and other steps to control their weight than did their more-svelte peers.

The findings offer guidance in targeting girls who might be most vulnerable to weight issues.

"Health care providers and school personnel might ask adolescent girls about their peer crowd affiliations in order to help identify adolescents with the highest levels of risky behaviors," the authors conclude in this month's Journal of Youth and Adolescence.

What also seems to help build healthy eating habits in teens is encouraging family meals, according to Project EAT (eating among teens), a long-term study of nearly 5,000 adolescents and their families conducted at the University of Minnesota.

The research found that family meals are linked to better diets, including more fruit and vegetables, fewer soft drinks and less dietary fat, said Dianne Neumark-Sztainer, professor of epidemiology at the University of Minnesota School of Public Health and a lead investigator of Project EAT.

Children from families that regularly eat together also seem to have a lower risk of developing eating disorders such as anorexia and bulimia. They're less likely to be overweight, and they also perform better in school.

Subscribe to the free Lean Plate Club e-mail newsletter at www.leanplateclub.com. Sally Squires is a writer for the Washington Post.