Evaluation of a new causal chain model for predicting embedded psychosocial and behavioral relationships in a community-based obesity treatment seeking maintained weight loss.

A new causal chain model positing theory- and research-based interrelationships among psychosocial and behavioral variables leading to weight loss and its maintenance was assessed. Two samples of women participating in community-based cognitive-behavioral obesity treatments were assessed over either 6 months (weight loss phase; N = 103), or additionally including Months 6-12 (weight-loss maintenance phase; N = 101). Analyses first evaluated whether baseline physical, demographic, behavioral (physical activity, fruit/vegetable intake), and/or psychosocial (self-regulation, self-efficacy, negative mood) variables significantly predicted weight change. Further analyses assessed whether changes in model-based behavioral and psychosocial variables significantly differed by groupings of participants based on their short-term weight loss and weight-loss maintenance/further loss. The predictive value of changes in the psychosocial variables on behavioral changes was next assessed, also accounting for group. Finally, mediation, moderation, and moderated mediation analyses tested proposed causal chain-based interrelationships among variables. Of the 12 variables assessed at baseline, only weight was inversely associated with lost weight, and only fruit/vegetable intake was positively associated with effects during the weight-loss maintenance phase. Overall improvements in behavioral and psychosocial variables were significantly greater in participant groupings with better weight loss and weight-loss maintenance results. Changes in self-regulation, self-efficacy, and mood significantly predicted the weight-loss behavior changes, unaffected by group. Results from the five mediation, moderation, and moderated mediation analyses supported hypotheses based on the new causal chain model. The field testing indicated adequacy of the new causal chain model and informed architectures of behavioral obesity treatments concerned with long-term reductions in excess weight.