Parent weight change as a predictor of child weight change in family-based behavioral obesity treatment

Background: Family-based behavioral weight control treatment involves the parent in the modification of child and parent eating and activity change. Objective: To assess if parent standardized body mass index (z-BMI) change predicts child z-BMI change. Design: Secondary data analysis based on parent and child z-BMI changes from 3 family-based, randomized, controlled weight control studies. Hierarchical regression models tested whether parent z-BMI change increased prediction of child z-BMI change through treatment and 24-month follow-up beyond other factors that influence child weight change, such as child age, sex, socioeconomic status, and baseline child and parent z-BMI. Differences in child z-BMI change as a function of quartiles of parental z-BMI change were tested using an analysis of covariance. Setting: Pediatric obesity research clinic. Participants: Obese 8- to 12-year-old children and their parents from 142 families who participated in family-based weight control programs. Main Outcome Measures: Child and parent z-BMI changes over time. Results: Parent z-BMI change significantly predicted child z-BMI change for the 0- to 6-month (P<.001) and 0- to 24-month (P<.009) time points. In hierarchical regression models, parent z-BMI change was a significant incremental predictor of child z-BMI change at 6 and 24 months, with the additional r(2) ranging from 11.6% at 6 months (P<.001) to 3.8% at 24 months (P=.02). Parents in the highest quartile of z-BMI change had children with significantly greater z-BMI change than that of children with parents in the other quartiles (P=.01). Conclusion: Parent z-BMI change is an independent predictor of obese child z-BMI change in family-based behavioral treatment, and youth benefit the most from parents who lose the most weight in family-based behavioral treatments.