Child Maltreatment and Body Mass Index over Time: The Roles of Social Support and Stress Responses.

An unhealthy body mass index (BMI) trajectory can exacerbate the burdens associated with child maltreatment. However, we have yet to explain why the relationship between maltreatment and BMI trajectories exists and what allows individuals to attain healthy BMI trajectories despite adversity. Guided by the Transactional Model of Stress and Coping, we evaluated (1) if peer friendship and adult mentors moderate, and (2) if impulsivity and depressive symptoms mediate, the relationship between maltreatment experiences and average excess BMI. We used data from four waves of the National Longitudinal Study of Adolescent to Adult Health (n = 17,696), following adolescents from ages 13-21 (Wave I) to 24-31 years (Wave IV). We did not find evidence of significant moderation or mediation of the maltreatment experience to average excess BMI relationship. However, models did demonstrate a relationship between peer friendship quality and average excess BMI, such that higher quality protected against higher average excess BMI (B = -0.073, s.e. = 0.02, p < 0.001). Age of maltreatment onset was also associated with average excess BMI, such that maltreatment onset in adolescence was associated with a higher average excess BMI (B = 0.275-0.284, s.e. = 0.11, p = 0.01). Although we found no evidence of moderation by social support or mediation by stress responses of the relationship between maltreatment experiences and average excess BMI, peer friendship appears to protect against higher average excess BMI from adolescence to young adulthood for all adolescents. Future public health interventions should consider how to leverage friendship in obesity prevention efforts.