Do participant, facilitator, or group factors moderate effectiveness of the Body Project? Implications for dissemination

•Baseline eating disorder symptoms significantly moderated treatment effects.•Participants with high baseline symptom levels benefited most.•Effectiveness did not vary by facilitator education, age, BMI, or sex.•Group size and attendance rate did not predict treatment effects.

The Body Project is a dissonance-based selective eating disorder prevention program with a broad evidence-base. The study sought to determine if previous findings regarding participant moderators replicate in an effectiveness trial under more real-world conditions. This study also had the novel aim of examining facilitator characteristics and group-level variables as potential outcome predictors. These aims are critical for understanding when the intervention is most effective and for whom. Participants were 408 young women with body image concerns recruited from seven universities. Change in eating disorder symptoms at 1-year follow-up was the primary outcome. Intervention effects were significant for both participants who had low or high baseline symptom levels, but the effect size was approximately twice as large for participants with high initial symptom levels (d = 0.58 vs. 0.24). Intervention effects were not predicted by facilitator factors (education, age, BMI, sex) or by group size or attendance rate. This study demonstrates that participants with either low or high eating disorder symptoms will benefit from the intervention but if resources are limited, targeting those with elevated eating disorder symptoms may be sensible. Results also suggest that a wide variety of facilitators can effectively deliver the Body Project, which has encouraging implications for dissemination.