Objective: To evaluate demographic and psychosocial predictors of attrition and weight loss in a behaviorally based adolescent weight control trial.

Methods and Procedures: Adolescents (N = 76) aged 13–16 years and 20–80% overweight (M = 60.56%, s.d. = 15.17%) received standard group-based behavioral treatment as part of a randomized trial comparing different activity interventions for overweight adolescents. Anthropometric and psychosocial measures were obtained at baseline and after the 16-week intervention.

Results: Higher parent (P < 0.01) and adolescent BMI (P < 0.05) at baseline, as well as ethnic minority status (P < 0.05) were significantly associated with attrition in univariate analyses. Parent BMI remained the only significant predictor of attrition in multivariate analyses. BMI change for completers (N = 62) was highly variable, ranging from −6.09 to +1.62 BMI units. Male gender (P < 0.01) was a significant predictor of reduction in BMI, whereas not being from an ethnic minority group (P < 0.05) and attendance at group sessions (P = 0.05) were associated with ≥5% absolute weight loss in multivariate analyses. Absolute weight loss during the first 4 weeks of the program was strongly associated with weight loss (pr = 0.44, P < 0.001) during the remainder of the intervention. Psychosocial variables were unrelated to attrition or treatment outcome.

Discussion: These findings highlight the potential importance of attending to parental BMI in efforts to retain adolescent participants in treatment, as well as the need to develop weight control interventions that are more effective for ethnic minority youth.