Exploring Dietary Restraint as a Mediator of Behavioral and Cognitive-Behavioral Treatments on Outcomes for Patients With Binge-Eating Disorder With Obesity.

OBJECTIVE

To explore dietary-restraint as a mediator of binge eating and weight-loss outcomes within a randomized controlled trial comparing cognitive-behavioral therapy (CBT) and behavioral weight loss (BWL) for binge-eating disorder (BED) with obesity.

METHODS

Ninety participants were randomly assigned to CBT or BWL and assessed by evaluators blinded to conditions at pretreatment, throughout-, and post-treatment (6 months). Three dietary-restraint measures (Eating Disorder Examination-Questionnaire [EDE-Q]-Restraint, Three-Factor Flexible-Restraint and Rigid-Restraint) were administered at pretreatment and after 2 months of treatment. Regression models examined whether changes at 2-months in the restraint scales mediated the effects of treatment (CBT versus BWL) on binge eating and weight-loss outcomes at post-treatment.

RESULTS

CBT and BWL had similar binge-eating outcomes and similar changes in EDE-Q-restraint and flexible-restraint. BWL had greater 2-month increases in rigid-restraint and greater weight-loss at posttreatment than CBT, with results suggesting 2-month changes in rigid-restraint mediated the greater difference (>7 pounds) in weight-loss. The observed mediation effect of 2.92 suggests 39% of total treatment-effect on weight-loss was mediated through 2-month increases in rigid-restraint.

DISCUSSION

This secondary analysis within a trial comparing CBT and BWL for BED suggests early-change in rigid-restraint has a mediating effect of BWL on weight-loss. Findings indicate that BWL improves binge eating and challenge views that dietary-restraint might exacerbate binge eating in BED with obesity. Findings require confirmation using hypothesis-testing in future trials.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT00537758 ("Treatment for Obesity and Binge Eating Disorder").