Healthy Teens @ School: Evaluating and disseminating transdiagnostic preventive interventions for eating disorders and obesity for adolescents in school settings.

•The Healthy Teens @ School study is a multi-country cluster-randomized controlled trial (RCT) comparing the effectiveness of an unguided, online, multi-level intervention for promoting a healthy lifestyle and reducing problematic eating behavior, eating disorder and obesity risk among students aged 14 to 19 years with control condition.•The intervention is an adapted version of an evidence-based program developed in the USA (StayingFit). Participants of the intervention group are assigned to either a “Weight Management” track or “Healthy Habits” track.•The primary outcome is intuitive eating, secondary outcomes are eating disorder symptomatology, body image concerns, body mass index, food intake, physical activity, self-esteem, stress coping, depression, and anxiety.•The results from this study will add to the understanding of how to address eating and weight related problems in adolescents and will shed light on the feasibility of implementing online prevention programs in school routine in Austria and Spain.•As part of the larger ICare project this RCT will determine how an adapted version of StayingFit is disseminated within Europe.