Their schoolmates’ weight determines whether teenage high school girls will try to lose pounds, new research finds, and the school environment plays a big role in the decision.

Although fashion magazines and celebrity culture equate ‘thin’ with ‘beautiful,’ the study in the March issue of Journal of Health and Social Behavior found that girls tend to view their body image in comparison to the peers they see every day in school — and being overweight might be perfectly fine.

“Our findings provide evidence that girls’ weight-control behaviors are more complicated than often assumed,” said lead study author Anna Mueller, at the University of Texas at Austin. “Every school does not have the same emphasis on being thin and losing weight, and even within schools, girls respond to the school culture differently.”

The researchers used data from the National Longitudinal Study of Adolescent Health, which contains a national sample of adolescents in grades 7 to 12 in 132 middle and high schools across the country. The researchers evaluated information given by about 4,000 adolescent high school girls.

Mueller and her colleagues looked at responses to the question, “Are you trying to lose weight, gain weight or stay the same?” They also considered each girl’s self-reported body mass index (BMI) to determine who was overweight or underweight, according to standards set by the Centers for Disease Control and Prevention.

The study found most girls would behave in the manner if a majority of their peers of the same size were doing the same. For example, girls in schools with a higher average female BMI are less likely to try losing weight. On the other hand, an average-weight girl would be increasing likely to say she is trying to lose weight as the number of underweight girls in her school rose.

“What our findings showed was that girls were more aware of what others like them were doing,” said Mueller. “Underweight girls were not likely to be trying to lose weight, unless they were in schools where underweight girls regularly reported trying to lose weight.”

Jeanie Alter, lead evaluator of the Indiana Prevention Resource Center at Indiana University’s School or Health, Physical Education, and Recreation echoed Mueller’s point. Alter specializes in adolescent health.

“It is not surprising that girls’ behavior would be influenced by the behaviors of their peers, whether they be perceived or real,” Alter said . “This is true for many types of behaviors including risky behaviors, such as substance use. Perceptions that ‘everyone is doing it’ are powerful motivators.”

The researchers concluded that because schools could play such an important role in a girl’s decision about weight control, the school environment offers the optimal opportunity to educate about body image and healthy behaviors.

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The Journal of Health and Social Behavior is a quarterly journal of the American Sociological Association.

Mueller AS, et al. Sizing up peers: adolescent girls’ weight control and social comparison in the school context results of a factorial priming experiment. J Health Social Behav 51(1), 2010.

Source:  Health Behavior News Service