A cognitive-behavioral mechanism leading to adolescent obesity: children's social images and physical activity.

BACKGROUND Increasing levels of youth obesity constitute a threat to the nation's health, and identification of the influences during childhood that lead to youth obesity is urgently needed. Physical activity is one such influence that is potentially modifiable. PURPOSE This study examined the influence of children's social images of other children who engage in physical activity on the development of their own physical activity over 3 years and related growth in physical activity to levels of obesity 2 years later. METHODS Participants (N = 846, 50% female) were members of the Oregon Youth Substance Use Project, a longitudinal study of a community sample. The racial/ethnic composition of the sample was 86% Caucasian; 7% Hispanic; 1% Black; and approximately 2% each of Asian/Pacific Islander, American Indian, or Alaskan Native, and other or mixed race/ethnicity. The mean age at the first assessment was 9.5 years. A model examining the effect of early social images on the growth of physical activity (athleticism modeled as a curve of factors) predicting obesity was evaluated using latent growth modeling. RESULTS More favorable social images predicted the initial levels (i.e., intercept) but not the change over time (i.e., slope) of children's athleticism, and both the intercept and the slope of athleticism predicted obesity. CONCLUSIONS Children's social images of exercise in early childhood influence their subsequent activity levels, and hence obesity, and should be targeted in obesity prevention interventions.