A new study of childhood obesity in the United States has found that some social factors, such as the presence of friends, may put overweight youths at greater risk of overeating.

The research, published in the August issue of the American Journal of Clinical Nutrition, demonstrates that friends may act as "permission givers" on children's food intake.

"These results are important, considering the role of friends as agents of change in childhood and adolescence," said Sarah Salvy, Ph.D., assistant professor in the Division of Behavioral Medicine, Department of Pediatrics, University at Buffalo School of Medicine and Biomedical Sciences.

"Overweight children are more likely to find food more reinforcing than non-overweight youth," she continued. "Being in the company of overweight peers may give them the permission to eat more or may decrease their inhibitions, increasing what are seen as the norms of appropriate eating, or how much one should eat."

The study involved 23 overweight and 42 normal weight children between the ages of 9 and 15, who were randomized to participate with either a friend or an unfamiliar person of a similar age. After randomization, there were 33 friend pairs and 39 "unfamiliar" pairs.

Before taking part in the study experiment, participants listed what they had eaten in the past 24 hours to make sure they hadn't eaten anything during the previous two hours, and rated their hunger level.

Each participant pair spent 45 minutes in a room equipped with games, puzzles and individual bowls of low-calorie, "nutrient dense" baby carrots and grapes, and high-calorie "energy-dense" potato chips and cookies. The children were told they could eat as much or as little as they wanted, but were asked to eat from their own bowls only.

Researchers observed the children via closed-circuit television and recorded their activities. At the end of the session, they weighed the snacks that weren't eaten to determine how much each participant had consumed and to calculate calories.

Results showed that friends who ate together consumed more food than participants who were paired with someone they didn't know, and that friends were more likely to eat similar amounts than participants paired with a stranger.

However, overweight children who were paired with an overweight peer, whether friend or stranger, ate more than the overweight participants who were paired with a normal weight youth.

"These findings indicate that both overweight and normal weight participants eating with a friend ate significantly more than did participants eating in the presence of an unfamiliar peer," Salvysaid. "These results are consistent with research in adults, which showed that eating among friends and family is distinctly different than eating among strangers.

"Given the impact of friends on eating behavior, it appears that if we hope to change the growing obesity epidemic among children, friends and family need to be involved," said Salvy. "If the environment in which children live doesn't change -- if family meals remain high calorie and overeating is the norm -- any progress children may make in their eating behavior won't last."

Salvy currently is investigating the influence of a parent versus a friend on children's and adolescents' eating behavior.

The research was supported by a grant to Salvy from the National Institute of Child Health and Human Development.

For more information on the University at Buffalo, visti www.buffalo.edu.