Social Transmission of Weight-Related Behaviors among Adolescents

Objective: To investigate whether social interactions in friendship networks influence weight-related behaviors of adolescents.

Methods: Using data from a nationally representative survey of adolescents we utilize multivariable regression analysis to examine the association between eight individual and peer weight-related behaviors. The behaviors examined are: exercising regularly, playing sports, hours of TV/Video viewing, six or fewer hours of sleep, eating breakfast, eating fast-food, eating five servings of fruits/vegetables, and consuming calorie-dense snacks. Controls for health endowments, preferences, and common environmental factors were included to adjust for correlated effects.

Results: Significant positive associations between peer average and individual behavior for exercise, sport, and eating fast food. A 10% increase in the fraction of friends who engage in a sport is associated with a 1.32% (p=0.000) increase in the probability of doing a sport. A 10% increase in the fraction of friends exercising increases the chance that the individual exercises by 0.68% (p=0.026). A 1-unit increase in the average number of fast food meals consumed in the friend network increases the number of fast food meals the individual consumed by 0.15 (p=0.000). Hours of TV/Video viewing, reduced sleep time, and having breakfast, five servings of fruits/vegetables and calorie-dense snacks were not found to be consistently affected by peers' engagement in such activities.

Conclusions: Evidence consistent with peer effects in exercise, sports, and consumption of fast food is provided. The social transmission of weight-related behaviors emerges as an explanation for the spread of weight gain and obesity in social networks found in recent research.