Girls who don't get enough exercise as tweens will gain much more as they grow, a new study shows.

By Beth Turner
October 05, 2005

July 27, 2005 — According to a new study, girls in the United States who were inactive during adolescence gained an average of 10 to 15 pounds more than active girls; they also had an increase of body mass index (BMI), which is a measure of body weight adjusted for height.

The 10-year observational Health and Grow Study, which was funded by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health and published in The Lancet, found that at ages nine and 10, there was only about a four- to five-pound difference between girls who were evaluated as "active" (the equivalent of five or more brisk 30-minute walks per week) and those who were seen as "inactive" (the equivalent of two-and-a-half or fewer brisk 30-minute walks per week). However, the difference grew in the following nine years, with inactive girls winding up approximately 10 to 15 pounds heavier than their active counterparts.

Total calorie intake increased only slightly and was not associated with the weight gains.

"These results show that many girls are at a literal standstill when it comes to exercise and physical activity in their pre-teen and teen years," NHLBI Director Elizabeth G. Nabel, M.D., said in a statement. "As parents, educators, and health care providers, we can do a lot to encourage girls to continue physical activity throughout their adolescence, a step that has been shown to help them maintain a healthy weight."

While 10 to 15 pounds may not sound like a lot, on a teenage girl it can add as much as 10 to 20 percent to her normal body weight. Plus, the percentage of overweight children in America has increased steadily over the past 10 years: Today, more than 9 million children and teens (ages six to 19) are considered overweight, according to the Centers for Disease Control and Prevention. When kids are overweight or obese, they are more likely to develop health problems such as Type 2 diabetes, hypertension, and heart disease.

More than 2,200 girls from three U.S. cities participated in this recent study of obesity. At each visit, the girls' BMI and skin fold measurements (another indication of being overweight and obese) was measured. Additionally, the girls filled in a questionnaire about their physical activity and diet.

Differences were noted between the black and white participants in BMI, food intake, and activity levels. Girls who self-reported their race as black were consistently heavier than those who reported their race as white, and their calorie intake was higher, and increased with age.

What do you think of this study? Do your children get enough daily exercise? Do you think you got more exercise as a child? Do you worry that your son or daughter will be overweight? Share your thoughts on our message board below:

Additional resources from

Healthy Kids

Get Moving

Parents Magazine


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