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Physically active teens less likely to become overweight as young adults

January 08, 2008

Participating in school-based physical education and certain extracurricular physical activities during adolescence may be associated with a lower risk of being overweight as a young adult, according to a report in the January issue of Archives of Pediatrics & Adolescent Medicine, one of the JAMA/Archives journals.

About 16 percent of U.S. teens are overweight or obese, according to background information in the article. Eighty-five percent of obese adolescents become obese adults. "In the pediatric population, adolescent overweight is the best predictor of adulthood overweight; however, to date, no single intervention in adolescence has proved to be effective in reducing the transition to adult overweight," the authors write.

David Menschik, M.D., M.P.H., then at Johns Hopkins University, Baltimore, and now at the Food and Drug Administration, Rockville, Md., and colleagues studied 3,345 teens in grades eight through 12 who participated in the National Longitudinal Study of Adolescent Health. In 1996, participants took an in-home survey, reporting on how often they participated in physical activities both at school and outside of school. They then reported their height and weight five years later, in 2001 or 2002.

"Increasing participation in certain extracurricular physical activities and physical education decreased the likelihood of young adulthood overweight," the authors write. "Regarding extracurricular physical activities, the likelihood of being an overweight adult was reduced most (i.e. 48 percent) by performing certain wheel-related activities (i.e. rollerblading, roller skating, skateboarding or bicycling) more than four times per week."

For every weekday that teens participated in physical education at school, their risk of being overweight as young adults was reduced by 5 percent. Those who had physical education five days per week had 28 percent lower odds of being overweight as young adults.

In general, the effects of physical activity were stronger for teens who began as normal weight than those who were overweight, suggesting that exercise is more effective for maintaining a normal weight than encouraging weight loss. "Accordingly, a greater emphasis on prevention, rather than intervention, may be well warranted in approaching the obesity epidemic," the authors write.

"In the current climate of decreasing adolescent physical activity in and out of school, it is important for policy makers to have firm evidence that justifies increasing time and bolstering resources for quality exercise programs and sports," they conclude. "In view of an obesity epidemic costing the United States an estimated $117 billion annually, policy makers now have evidence that a relatively low-cost strategy may offer a long-lasting solution."

JAMA and Archives Journals