Effect of A Healthy Body Image intervention on risk- and protective factors for eating disorders : A cluster randomized controlled trial

Abstract

Objective: To investigate the immediate and 12-months effects of a school-based intervention aiming to reduce risk and enhance protective factors for eating disorder development in high school boys and girls. Method: In total, 4,149 adolescents from 30 high schools were eligible for inclusion and 2,446 consented to participate and were randomly allocated to the Healthy Body Image (HBI) intervention or a control group (classes as usual). The HBI intervention is multicomponent consisting of three workshops targeting body image, social media usage and lifestyle. Linear mixed model and intention-to-treat analyses were applied to investigate the effects of group, time, and gender at posttest, 3-, and 12-months follow-up. The main outcome variable was weight and shape concerns, and secondary outcome variables were self-esteem, mental distress, body image flexibility, thin internalization, muscular internalization, drive for leanness, perceived media pressure, protein- and creatine supplement use, and diet aid use. Results: The HBI intervention significantly reduced eating disorder risk factor scores related to ED pathology, thin internalization and perceived pressure from media, which was particularly pronounced in girls. Positive intervention effects on body image flexibility were only observed at posttest for boys but grew increasingly larger for girls across the 12-month follow-up time span. Favorable intervention effects on protein and creatine supplement use were only present at 3-months follow-up in boys solely. A general favorable intervention effect was observed for self-esteem, mental distress, muscular internalization, and drive for leanness. Conclusion: The HBI intervention produced consistent reductions in risk factors and enhancements in protective factors associated with eating disorder development in adolescents.