OBJECTIVES-Studies suggest that breastfeeding is protective for later obesity; however, this association has not held among all racial and socioeconomic status groups. Racial and socioeconomic status differences in breastfeeding behavior have also been noted. In this study, we formally test whether breastfeeding mediates the relationship between race and socioeconomic status with adolescent adiposity.METHODS-Data were analyzed from 739 black and white 10-to 19-year-old adolescents who participated in a large, school-based study. Parents provided information on parental education, used to measure socioeconomic status, and whether the child was breastfed as an infant. BMI was used to measure adolescent adiposity and was analyzed as a continuous measure (BMI z score) using linear regression and categorically (BMI ≥85th and ≥95th percentile) using logistic regression.RESULTS-Black adolescents and those without a college-educated parent were less likely to have been breastfed for >4 months. Race and parental education were each independent predictors of BMI z score and of having BMI ≥85th percentile or BMI ≥95th percentile. When added to the model, being breastfed for >4 months was also independently associated with lower BMI z score and lower odds of having BMI ≥85th percentile or BMI ≥95th percentile. Inclusion of being breastfed for >4 months resulted in a 25% decrease in racial and parental education differences in adolescent BMI z score, supporting partial mediation.CONCLUSIONS-Having been breastfed for >4 months was associated with lower adolescent BMI z score and lower odds of having a BMI ≥85th percentile or BMI ≥95th percentile, independent of race or parental education. Furthermore, these analyses suggest that being breastfed for >4 months partially explains the relationship between social disadvantage and increased adiposity. Increasing breastfeeding duration could result in lower adolescent adiposity for all racial and socioeconomic status groups and potentially minimize socioeconomic disparities in adiposity.Keywords adolescent obesity; breastfeeding; epidemiology; racial differences; socioeconomic status Copyright © 2008 Adolescent obesity is a major public health issue that has been increasing in the past 2 decades. This problem disproportionately affects socially disadvantaged groups. Recent national studies have found that >40% of black adolescents aged 12 to 19 are at risk for overweight (eg, BMI ≥85th percentile for age and gender) or are overweight (BMI ≥95th percentile) compared with 26.5% of white teens and that this proportion has been increasing. 1,2 In addition, low socioeconomic status (SES) is frequently associated with higher rates of overweight. [3][4][5][6] Thus, the search for causes and potential interventions to decrease these disparities and reduce the prevalence of overweight is crucial.Breastfeeding has been reported as being protective against obesity, but this association is somewhat controversial. Whereas several studies found significantly lower obesity rates among th...