Understanding Weight Change in Cognitive Behavioural Therapy for Adults With Eating Disorders: A Systematic Review...

To examine body mass index (BMI) change during and following cognitive behavioural therapy for eating disorders (CBT-ED), separately for underweight and non-underweight participants.

Random-effects meta-analyses synthesised 55 studies. Pre-to post-treatment and follow-up BMI changes were analysed by baseline weight status. Treatment setting was examined among underweight participants.

BMI increased substantially in underweight participants (g = 1.15, 95% CI [0.43, 1.88], k = 26) and slightly in non-underweight participants (g = 0.38, 95% CI [0.10, 0.65], k = 43) from pre-to post-treatment. Heterogeneity was very high (I² = 98.90% and 96.05%, respectively). Among underweight participants, effects were positive in inpatient (g = 1.53) and community settings (g = 0.84), with no significant between-setting difference (p = 0.168). At follow-up, BMI remained higher than baseline in underweight participants (g = 0.91, 95% CI [0.39, 1.43]) but not in non-underweight participants (g = 0.11, 95% CI [-0.11, 0.33]).

BMI change following CBT-ED differs by baseline weight status and should be interpreted in relation to treatment goals. However, the conclusions should be considered cautiously, given the low quality of the research, and future studies should be more attentive research quality.