Introduction: Obesity during adolescence is particularly challenging. Our aims were to identify parents’ and adolescents’ perceptions regarding obesity, as well as family dynamics before and after family-based behavioral therapy (FBBT) to improve obesity. Method: Using a qualitative approach, 23 parents and 21 adolescents aged 12 to 18 years participated in 6 focus groups, before and after FBBT. Focus groups were audio-taped, transcribed verbatim, and analyzed using content analysis. Results: Transcript analyses suggested 3 major themes from both adolescents and parents: obesity as a source of strong negative emotions, adolescents and weight-control responsibility, and disruption in family dynamics. FBBT improved self-confidence and family functioning, allowing for behavioral changes. Both adolescents and their parents felt empowered. Discussion: Family dynamics are an important issue in weight-loss treatment during adolescence. Including both parents and adolescents in therapy is crucial for tackling obesity and addressing health needs related to this age group.