BACKGROUND/OBJECTIVES: Bariatric surgery produces robust weight loss, however, factors associated with long-term weight-loss maintenance among adolescents undergoing Roux-en-Y gastric bypass surgery are unknown. SUBJECTS/METHODS: Fifty adolescents (mean +/- s.d. age and body mass index (BMI) = 17.1 +/- 1.7 years and 59 +/- 11 kg m(-2)) underwent Roux-en-Y gastric bypass surgery, had follow-up visits at 1 year and at a visit between 5 and 12 years following surgery (Follow-up of Adolescent Bariatric Surgery at 5 Plus years (FABS-5+) visit; mean +/- s.d. 8.1 +/- 1.6 years). A non-surgical comparison group (n = 30; mean +/- s.d. age and BMI = 15.3 +/- 1.7 years and BMI = 52 +/- 8 kg m(-2)) was recruited to compare weight trajectories over time. Questionnaires (health-related and eating behaviors, health responsibility, impact of weight on quality of life (QOL), international physical activity questionnaire and dietary habits via surgery guidelines) were administered at the FABS-5+ visit. Post hoc, participants were split into two groups: long-term weight-loss maintainers (n = 23; baseline BMI = 58.2 kg m(-2); 1-year BMI = 35.8 kg m-2; FABS-5+ BMI = 34.9 kg m(-2)) and re-gainers (n = 27; baseline BMI = 59.8 kg m(-2); 1-year BMI = 36.8 kg m(-2); FABS-5+ BMI = 48.0 kg m-2) to compare factors which might contribute to differences. Data were analyzed using generalized estimating equations adjusted for age, sex, baseline BMI, baseline diabetes status and length of follow-up. RESULTS: The BMI of the surgical group declined from baseline to 1 year (-38.5 +/- 6.9%), which, despite some regain, was largely maintained until FABS-5+ (-29.6 +/- 13.9% change). The BMI of the comparison group increased from baseline to the FABS-5+ visit (+ 10.3 +/- 20.6%). When the surgical group was split into maintainers and re-gainers, no differences in weight-related and eating behaviors, health responsibility, physical activity/inactivity, or dietary habits were observed between groups. However, at FABS-5+, maintainers had greater overall QOL scores than re-gainers (87.5 +/- 10.5 vs 65.4 +/- 20.2, P < 0.001) and in each QOL sub-domain (P < 0.01 all). CONCLUSIONS: Long-term weight outcomes for those who underwent weight-loss surgery were superior to those who did not undergo surgical treatment. While no behavioral factors were identified as predictors of success in long-term weight-loss maintenance, greater QOL was strongly associated with maintenance of weight loss among adolescents who underwent Roux-en-Y gastric bypass surgery surgery.