Adolescents who participate in physical education at school are more likely to maintain a normal weight as young adults, according to a study by researchers at the Johns Hopkins Bloomberg School of Public Health. For each weekday of physical education at school the odds of being an overweight adult decreased by 5 percent. Participation in all five days of physical education decreased the odds of being an overweight adult by 28 percent.

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.

"These findings underscore the important role that school-based and extracurricular physical activities play in reducing the likelihood of becoming an overweight adult," said Robert Wm. Blum, MD, MPH, PhD, the study's senior author. "While physical education was not a good weight-loss mechanism over time, it appears to have a positive impact in helping teenagers maintain a healthy weight into young adulthood," added Blum, who is the Bloomberg School's William H. Gates Sr. Professor and Chair in Population and Reproductive Health.

The Hopkins team studied 3,345 teens in grades eight through 12 who took part in the National Longitudinal Study of Adolescent Health at which time the teens were surveyed on their participation in physical education and physical activities outside of school. The researchers then followed up with the participants five years after leaving school to check their height and weight.

The researchers found that increased participation in physical education and certain extracurricular physical activities decreased the likelihood of being overweight as an adult. The likelihood of being an overweight adult was most reduced among teens who participated in wheel-related extracurricular activities, such as rollerblading, biking or skate-boarding more than 4 times per week. These teens were more than twice as likely to maintain a normal weight as adults compared to their less active peers. However, no impact was detected when physical activities were performed fewer than three times per week.

The American Academy of Pediatrics and the U.S. Department of Health and Human Services recommend physical education at all grade levels. Studies show that less than half of high school students are enrolled in physical education courses. Only 6 percent of junior high schools and 5 percent of senior high schools offer daily physical education, according to the Institute of Medicine.

"Sixteen percent of adolescents in the United States are overweight or obese and 85 percent of obese teens will become obese adults. School-based physical education could be a low-cost strategy and a long-lasting solution to adult obesity," said Blum.

This study was supported in part by the William H. Gates Sr. Endowment, Johns Hopkins Bloomberg School of Public Health.