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+ ( -2 9.6±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.