Correlates of weight loss and muscle-gaining behavior in 10- to 14-year-old males and females.

Background: This study examined the influence of appearance and social acceptance esteem, awareness and internalization of media stereotypes, body size acceptance, and teasing on the weight loss and muscle-gaining behaviors of 10- to 14-year-old boys and girls.

Methods: Male (n = 670) and female (n = 788) students were drawn from one of four public senior middle schools (grades 6-8) in Southern Ontario as part of a longitudinal outcome-based study. Students' baseline self-report questionnaires, measuring the above variables, were analyzed for the purposes of this study.

Results: A higher percentage of girls reported engaging in weight loss behaviors, whereas a higher percentage of boys admitted to muscle gaining and the use of specific weight control methods such as laxative use and vomiting. Regression analyses revealed that internalization of media messages and body size acceptance were equally predictive of boys' weight loss and muscle-gaining behaviors, while teasing was found to also predict their muscle-gaining behavior. Among the girls, appearance esteem, internalization of media stereotypes, and body size acceptance were predictive of weight loss behaviors. None of the study variables were predictive of girls' muscle-gaining behavior.

Conclusions: Weight loss and muscle-gaining behaviors appear to have their onset in children as young as 10 years. The findings support the need for prevention programs that focus on media literacy and ways to decrease weight-based teasing in the school setting.