Moderators and Mediators of a Digital Cognitive Behavior Therapy-Guided Self-Help Intervention for Eating Disorders: Informing Future Design Efforts

Objective: The Student Bodies-Eating Disorders intervention (SB-ED), a digital cognitive behavior therapy-guided self-help intervention for college women with an eating disorder, is effective for reducing eating disorder psychopathology. The purpose of this study was to evaluate moderators and mediators of the SB-ED intervention. To our knowledge, this is the first evaluation of clinical mediators of a digital intervention for women with eating disorders. Method: This is an exploratory secondary analysis of a cluster randomized trial comparing the SB-ED intervention to referral to usual care among 690 women at 27 United States colleges. Moderators included body mass index (BMI), race, ethnicity, weight/shape concerns, eating disorder impairment, thin ideal internalization, depression, anxiety, and motivation for treatment, assessed at baseline. Thin ideal internalization and depressive symptoms were tested as predictors at postintervention and mediators at 2-year follow-up. Outcome was change in global eating disorder psychopathology. Results: BMI moderated the effect of the intervention at follow-up (but not posttreatment), with individuals with a lower BMI experiencing more continued improvements in eating disorder psychopathology following the intervention than individuals with a higher BMI. Thin ideal internalization mediated the effect of the intervention at follow-up, and depression partially mediated the effect of the intervention at follow-up. Conclusions: Results of the mediator analyses suggest that helping college women reduce inflated internalization of the thin ideal and improve depressive symptoms leads to improvements in eating disorder psychopathology. Results also suggest opportunities to optimize the intervention so individuals across the BMI spectrum experience ongoing improvements over time.