A little physical education could sharply reduce obesity in children, new research shows.

Sept. 9, 2004 -- Just one extra hour of exercise a week could significantly cut obesity for five- and six-year-olds, especially girls, according to a new study.

Increasing physical activity by one hour per week leads to a .31 greater reduction in Body Mass Index (BMI) for overweight elementary school girls, the research says. The study, conducted by the Rand Corp. on behalf of the non-profit National Institute for Health Care Management (NICHM) Foundation, projects that at least five hours of gym time in kindergarten each week would reduce the prevalence of overweight young girls by 43 percent.

Right now, kindergarteners average only 57 minutes a week in gym classes the research says, and they only get an average of 65 minutes a week in first grade. About 10 percent of kindergarten girls are overweight today (by BMI definition); that would decline to 5.8 percent with at least five hours a week of physical activity.

"By systematically incorporating daily physical activity into young children's lives, we can successfully prevent childhood obesity for large populations of kids," said Nancy Chockley, president of the NICHM Foundation. "Increasing PE time is one of the few solutions in the struggle against overweight that is effective, practical, and can be replicated."

The research findings analyze the impact of expanding school PE on BMI, a measure of weight factoring in height. Even small shifts in weight loss of just three to five pounds, for example, can shift a significant number of overweight kids to "at risk" BMI status and a significant number of "at risk" children to healthy weight and BMI status:




BMI Percentile

Weight Status

65 lbs





57 lbs





50 lbs





When overweight boys had more PE time it also made a difference, but the results did not reach statistical significance.

In the past decade, as some schools have concentrated more on literacy, mathematics, and test-taking, they have had to scale back gym classes.

It's important to remember that exercise must be tied with better eating habits to address the nation's growing epidemic of childhood obesity.

Other notable findings of the study include:

  • Wide variations in PE time existed across grades and among schools. More than one in five first graders actually has PE time reduced or completely eliminated after kindergarten.
  • Schools with high proportions of low-income or minority students tended to have the least PE time.
  • The level of PE could reduce the proportion of kindergarten girls at-risk-for overweight by 60 percent.

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