Effects of Increased Physical Activity/Exercise on Long-Term Losses in Weight and Waist Circumference: Serial Mediation from Changes in Exercise-Related to Eating-Related Self-Regulation.

Background: Behavioral obesity treatments have generally been unsuccessful at facilitating long-term weight reductions. Increased physical activity/exercise is a strong predictor of maintained weight loss. It has been proposed this is more linked to increases in exercise-related self-regulation carrying-over to eating-related self-regulation than through direct energy expenditures.

Methods: Women with obesity participated in 10-month community-based behavioral treatments that had theory-based foci on either self-regulation skills building (n = 59) or knowledge of weight loss methods (n = 54). Physical activity/exercise, exercise-related self-regulation, and eating-related self-regulation were assessed at baseline and months 3, 6, and 12 in the prediction of weight and waist circumference changes over 24 months.

Results: Significant overall improvements on all measures were found, which were significantly greater in the self-regulation-focused group than the knowledge-focused group. Mean reductions in waist circumference/weight were - 4.64 cm/ - 5.17 kg (- 5.5% of baseline weight) and - 0.66 cm/ - 1.19 kg (- 1.2% of baseline weight), respectively. Aggregated data indicated that early increase in physical activity/exercise significantly predicted 24-month reductions in both weight and waist circumference. Serial mediation analyses indicated that a sequential path from exercise-related self-regulation (baseline-month 3) → eating-related self-regulation (baseline-month 6) → eating-related self-regulation (baseline-month 12) fully mediated the physical activity/exercise-weight/waist circumference change relationships. Energy expenditures from physical activity/exercise accounted for 21% of lost weight.

Conclusions: Findings of this field research supported benefits of progressively building self-regulation skills, first for physical activity/exercise then controlled eating, through accordingly focused behavioral treatments. Opportunities for tailoring large-scale community-based interventions grounded in theory were enhanced.