This study is a school-based cluster-randomized controlled trial conducted among adolescent athletes attending sports-specialized lower and upper secondary schools in Norway.
Based on statistical power analyses, approximately 1740 adolescent athletes aged 13-17 years are expected to participate in the study. The sample size calculation was based on effect sizes observed in the pilot study of the Young Athlete Body Project (0.40 for thin-ideal internalization and 0.23 for muscularity-ideal internalization), a significance level of α = 0.05, and 80% statistical power. The calculation accounted for the clustered study design by assuming an average cluster size of 60 students per school and an intraclass correlation coefficient (ICC) of 0.02. In addition, the sample size was adjusted for an anticipated attrition rate of up to 25%. Based on these assumptions, between 291 and 867 participants are required per study arm. To ensure adequate power for all primary outcomes and follow-up assessments, approximately 1740 participants will be recruited.
Participating schools will be randomized to either the intervention group or control group. Randomization will be conducted at the school level to minimize contamination between participants within schools. Data will be analyzed according to the intention-to-treat principle. Intervention effects will be evaluated using linear mixed-effects regression models with a random intercept for school to account for clustering at the school level.
The intervention, Young Athlete Body Project, is delivered during school hours over a five-week period and consists of two digital educational sessions followed by three in-person workshops. The educational sessions focus on (1) energy availability, nutrition, biological maturation and puberty in young athletes and (2) social media, body ideals and mental health in sport. These topics are part of the existing curriculum in sports-specialized lower and upper secondary schools and provide the foundation for the subsequent workshop activities. Students attending schools randomized to the intervention group will receive the educational sessions and take part in the workshops as part of their school program. Participation in the research component of the study, including completion of questionnaires and other study-related assessments, is voluntary and requires informed consent.
The workshops are conducted in small sex-specific groups of approximately ten participants and are led by trained instructors following a standardized intervention manual. The workshop content is adapted from the evidence-based Body Project and is based on cognitive dissonance principles. Through guided discussions, role-play activities, reflective exercises and written assignments, participants are encouraged to critically examine appearance ideals, body appearance pressures and sociocultural influences related to body image. The workshops also focus on strengthening body acceptance, reducing internalization of appearance ideals and developing strategies to cope with appearance-related pressures from sport, social media and society.
Data will be collected using self-report questionnaires administered at baseline, immediately following the intervention, and at 6-, 12-, and 24-month follow-up assessments. Outcomes will be assessed using the Body Appreciation Scale-2 (BAS-2), the Sociocultural Attitudes Towards Appearance Questionnaire-4 (SATAQ-4), the Eating Disorder Examination Questionnaire short form (EDE-Q short form), and additional questions assessing mental health and psychosocial functioning. In addition, a randomized subsample of participants will be invited to participate in qualitative interviews to evaluate their experiences with and perceived benefits of the program. All participants scoring ≥15 on the EDE-Q short form, together with a sex-matched sample of participants scoring below this cut-off, will be invited to complete the Eating Disorder Examination (EDE), a structured diagnostic interview assessing eating disorder symptoms, behaviors, and related cognitions. These interviews will be used to strengthen the validity of self-reported questionnaire data and provide a more comprehensive assessment of eating disorder outcomes.
The study will evaluate both short-term and long-term effects of the intervention and provide evidence regarding the effectiveness of a school-based body image and eating disorder prevention program specifically adapted for adolescent athletes.
