Baseline Psychosocial and Demographic Factors Associated with Study Attrition and 12-Month Weight Gain in the DIETFITS Trial.

Abstract

The purpose of this study was to examine correlates of failure-trial attrition and weight gain-in a randomized clinical weight-loss trial. The Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) trial included 609 adults (18-50 years; BMI 28-40). Participants were randomized to a 12-month healthy low-fat or healthy low-carbohydrate diet for weight loss. At baseline, participants completed psychosocial, demographic, and anthropometric measures. Stepwise logistic regressions identified baseline factors associated with (1) study attrition and (2) among trial completers, weight gain at 12 months. Having higher baseline food addiction and self-efficacy was linked to treatment failure. Being younger, not having a college education, having higher outcome expectations and quality of life, and having lower social functioning and self-control increased the odds of trial attrition. Identifying as other than non-Hispanic white; not being married or cohabitating; having higher cognitive restraint and self-control; and having lower amotivation, family encouragement, and physical limitations increased the odds of gaining weight by treatment's end. Participants' baseline psychosocial and demographic factors may support or impede successful weight loss. Trialists should attend to these factors when designing treatments in order to promote participants' likelihood of completing the trial and achieving their weight-loss goals.