Evaluating a Family-Dynamics Based Intervention for Overweight Adolescents: A Randomized Study

Background: To combat childhood obesity epidemic, family-based approach has been gradually developed as a preferred intervention. As of 2014, thirteen out of fifteen randomized controlled trials were rooted in behavior theory, focusing primarily on the parent-child subsystem through strengthening the parental role in modifying unhealthy lifestyle of children. These 15 RCTs called for advancing family-based interventions by targeting the family as a basic social system for change as children behaviors were influenced by the family interactions. Current studies also reported that dysfunctional family dynamics were associated with childhood obesity. There was a substantial lack of family-based interventions for adolescents. Based on the family systems theory, this study aimed to evaluate the effects of a family-dynamics based model, emphasizing on restructuring dysfunctional family patterns for cultivating adolescents’ healthy lifestyle and thus controlling weight.  

Method: A randomized experimental-control study was conducted between January 2010 and July 2011 in a university-based social work center. Ninety-three participants were recruited from 5 schools in Hong Kong, ages from 12 to 15-year-olds at or above the 85th BMI percentile. An “intention to treat” approach was adopted. The number of participants for the control group, the intervention group with adolescent  only, and the intervention group with both adolescent  and parent were 27, 32, and 34 respectively. There were two 12-month family-based curricula, one for adolescents while the other for parents. Both curricula covered a family approach to healthy diet and physical training, and healthy family dynamics. The control group received published information about healthy lifestyle.  Assessments were conducted at the baseline, 6, 12, 18 months. The main outcome measures were BMI z score, and overweight percentage. Other outcome measures included body fat, waist, physical activity checklist, 10-item food intake checklist, self-esteem questionnaire, systemic family questionnaire, family assessment devise, dietary assessment, and physical fitness test. Treatment effects are examined with Planned Contrasts (t-tests).

Results: There were reductions in three outcome measures over time. 1) BMI z-scores: reductions were highly significant (p = 0.00) for both intervention groups and Control. 2) Overweight percentage: reductions were highly significant (p = 0.00) for both intervention groups but not significant for Control. 3) Percentage body fat: reductions were highly significant (p = 0.00) for Adolescent and parent, significant for Control (p = 0.039), but insignificant for Adolescent only. Analysis was only done for males because the PBF of female adolescents is highly variable. The treatment effect of Adolescent and parent vs. Control was significant in overweight percentage reduction (Mean difference = 16.1%, p = .039), and close to significant in PBF reduction (Mean difference = 2.8%, p = 0.056) but insignificant in BMI z-score reduction. The treatment effects of Adolescent only vs. Control were insignificant in all outcome measures.

Conclusion and Implications: The findings support a family -dynamics based intervention in that it produced positive effects regarding weight loss in overweight and obese adolescents. In terms of the target of change, the results strongly suggest that involving both adolescents and parents in the intervention was more effective than the adolescents only.