Dissonance-based eating disorder prevention for young women in Portugal: examining the body project’s efficacy, delivery modality, and preference match

Eating disorders are prevalent among young women and entail negative personal and societal consequences. Investing in prevention programs could make a meaningful difference. The Body Project is a dissonance-based prevention program with extensive empirical support for improving eating disorders' symptomatology, risk factors, and protective factors. This study is the first to evaluate the efficacy and feasibility of the Body Project in Portugal. It is also the first to explore long-term modality differences in efficacy and whether matching participants to their preferred modality moderates intervention outcomes. A total of 147 female university students with body concerns, aged 18 to 30 years, were randomly assigned to one of the peer-led Body Project interventions -in-person or virtual - or to a waitlist control. Participants in the in-person and virtual Body Project reported high satisfaction with the intervention and showed significant improvements from pre- to posttest across outcomes compared to the waitlist, except for self-esteem in the virtual group. Improvements remained significant at 6- and 12-month follow-ups, except for negative affect and dieting behaviors at 12-month follow-up in the in-person group. While both interventions produced comparable outcomes, the in-person group showed larger immediate reductions in eating disorder symptomatology, whereas the virtual group showed delayed reductions. Matching participants to their preferred modality significantly moderated the effect of delivery modality on changes from pre- to posttest in thin-ideal internalization, dieting behaviors, eating disorder symptomatology, and body appreciation. Exploratory analyses suggested that matched participants tended to show larger gains in the in-person intervention, whereas unmatched participants tended to show larger gains in the virtual intervention. Implications, limitations, and recommendations are discussed.