Research about how peers influence weight outcomes among adolescents has yielded mixed findings. This paper seeks to not only estimate these peer effects, but also to distinguish between two mechanisms: social multiplier effects and social norm effects. After estimating an augmented spatial autoregressive model using data from the National Longitudinal Study of Adolescent to Adult Health Survey, this study finds significant peer interactions in body mass index, which can be explained by both

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... hanisms of peer influence; the social norm effect is much larger than the social multiplier effect. The estimated peer effects for overweight and obesity statuses suggest that peer effects are important for overweight status but not for obesity status, and peer influence for overweight status appears to operate solely through social multiplier effect. These findings provide important information for the design of obesity-prevention interventions in schools.