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Background Weight-loss interventions have had disappointing outcomes, partly because of a minimal understanding of associated psychological factors. Theory-based treatments often seek to build self-regulation for controlling eating – a strong predictor of weight loss. Mood changes associated with treatment may, however, affect self-regulatory changes in obese women. Self-regulatory changes may, reciprocally, impact mood. Consequently, the aim of this study was to (a) assess treatment-associated effects on depression, total negative mood, and self-regulatory skills usage, and (b) determine whether changes in mood mediate self-regulatory skill changes, and vice-versa.
Methods Women with severe obesity were randomly assigned to groups of exercise support plus either nutrition education (n = 134) or cognitive behavioral methods emphasizing the building of self-regulation skills for eating (n = 135). In addition to exercise support, the nutrition groups met every 2 weeks for 3 months, with follow-up after 6 months.
Results Significant overall improvements in self-regulation, depression, and total mood disturbance were found over 6 months, with changes in total mood disturbance and self-regulation significantly greater in the cognitive-behavioral treatment group. Because the mediating effects of mood changes on the relationship of treatment type and changes in self-regulation were significant, as was the mediation of self-regulation change in the treatment-mood change relationships, the criteria for reciprocal effects was met. For participants with high total mood disturbance scores, changes in total mood disturbance and selfregulation completely mediated the treatment-self-regulation and treatment-mood relationships, respectively. Post hoc testing indicated significant associations between participants’ exercise volume and improvements in their mood scores.
Conclusion Because treatment-induced changes in mood and self-regulation for eating may have reciprocal effects, methods for improving both should be incorporated in weight-loss treatments for obese women. Moderate physical activity may be a method for improving mood.