Longitudinal associations of family functioning with body mass index in Mexican-origin adolescents living in the U.S

Mexican-origin adolescents have a high prevalence of obesity. Research is needed to understand how family context may shape adolescent BMI. This study examined longitudinal associations of family functioning variables with the Centers for Disease Control and Prevention's modified BMI z-score (BMIaz) in 1175 Mexican-origin adolescents, and explored interactions with acculturation. Adolescents (50% female, aged 11-13 y in 2005-06) were identified from an ongoing cohort study of Mexican-origin adults in Houston, TX, and were assessed three times from 2005-06 to 2010-11. In multivariate linear mixed models stratified by gender, we assessed longitudinal associations of family cohesion and family conflict with adolescent BMIaz and explored interactions with language acculturation. We disaggregated the between- (mean) and within-person (individual deviation) components of family cohesion and family conflict to assess the effects on BMIaz. Approximately one-third of adolescents were obese at baseline, and BMIaz declined during the study. In girls, higher mean family cohesion and conflict were associated with steeper declines in BMIaz. Parental linguistic acculturation modified the relationship between within-person deviation in family cohesion and BMIaz in girls, such that high parental U.S. acculturation was associated with a stronger inverse association. There were no significant associations in boys. These findings highlight the potential importance of the family context to female adolescent BMI and the promise of addressing family context in obesity-related interventions.