Body Mass Index, Peer Victimization, and Internalizing Symptoms From Late Childhood Through Early Adolescence: Disaggregation of Within-Person and Between-Person Effects

Objective: The transition from late childhood to early adolescence is marked with considerable physical changes and increasing prevalence of peer victimization and affective problems. Children with high body mass index (BMI) during this period are vulnerable to peer victimization. High BMI and peer victimization are also associated with internalizing symptoms. Extant research on interrelations among these issues have primarily focused on the average associations for a given group without disentangling within- and between-person effects. Method: The National Institute of Child Health and Human Development, Study of Early Child Care and Youth Development data (N = 895) spanning from middle childhood through early adolescence (i.e., the third, fourth, fifth, and sixth grades) were used to delineate temporal dynamics of such associations. Results: The cross-lagged panel model revealed that BMI was positively associated with subsequent peer victimization, which in turn was positively related to later internalizing symptoms. Peer victimization and internalizing symptoms were reciprocally associated with each other over time. Random-intercept, cross-lagged panel model analyses identified a positive between-person association between BMI and peer victimization. At the within-person level, higher-than-usual scores in peer victimization were unidirectionally and positively associated with subsequent higher-than-usual scores in internalizing symptoms. No within-person mediation emerged. Conclusions: The inconsistency in results of different models highlighted the importance of disaggregating between- and within-person effects in the relations among BMI, peer victimization, and internalizing symptoms. Our findings provide insights for designing interventions targeting children with high BMI to reduce their risk for peer victimization and internalizing symptoms.