Predictors of Weight Loss Among Adults With Mental Illness: A Secondary Analysis of a Randomized Clinical Trial

This study assessed associations of motivation factors and precursor health behaviors with weight loss in the CoachToFit program for adults with mental illness.

This is a secondary analysis of a randomized trial comparing CoachToFit and usual care over 6 months at a Veterans Affairs medical center. Inclusion criteria were body mass index ≥30 kg/m² and diagnosis of major depressive disorder, bipolar disorder, or schizophrenia. Exclusion criteria were history of bariatric surgery or recent psychiatric hospitalization. The sample (N=256) had a mean±SD age of 53.5±13.0 years; 176 (69%) were male, 178 (70%) were White, and 199 (78%) were diagnosed as having major depressive disorder. Participants were assessed at baseline and at 6 months (postintervention) on weight, motivation factors (efficacy for healthy eating and exercise, confidence to improve health, importance assigned to weight loss, and stage of change for weight control), and precursor health behaviors (daily cups of sugary drinks consumed and physical activity days per week and minutes per day). The study assessed the relationships between study group and multiple motivation factors and precursor health behaviors and associations between weight loss and change over time on those factors.

Compared with usual care, CoachToFit significantly improved efficacy for eating healthily, exercising, and making healthy changes. CoachToFit (vs. usual-care) participants reported nearly 1 additional day of physical activity per week and had nearly twice the odds of being in a higher category of exercise minutes.

Physical activity and confidence for health improvement are important factors for weight loss programs among adults with mental illness.