The study found that children consistently increased their activity levels by 10 percent to be more in line with their peers.
Ray Browning, an assistant professor at Colorado State University's department of health and exercise science, praised the study and said it helps clarify "how relationships affect health-related behavior" even though "it is easy to look at a study like this and say 'duh.'"
However, he said, the study only looks at a few hours of the day. In the big picture, he said, it's "well-established" that peers make a major difference in teenagers when it comes to things like using drugs. But the influence of other kids is not as clear in younger kids.
To make things more complicated, "the friendships of young children are fairly dynamic," he said. "They're forming and reforming with some relatively high frequency."
By contrast, he said, "we tend to think of obesity as more of a chronic condition that we acquire over time. When the friendships are coming and going, you could make the argument that it may have less of an impact."
The study appears in the June issue of the journal Pediatrics, published online May 28.
For more on childhood obesity, visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Eric Tesdahl, M.A., graduate student, department of human and organizational development, Vanderbilt University, Nashville, Tenn.; Ray Browning, Ph.D., assistant professor, department of health and exercise science, Colorado State University, Fort Collins; June 2012 Pediatrics
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