Relations of change in fruit and vegetable intake with overall energy reduction and physical activity with weight change: Assessing theory-based psychosocial mediators.

BACKGROUND

Increased physical activity and fruit and vegetable (FV) intake are typically suggested to counter obesity. Sustained behavior change in those areas has, however, been poor, possibly because of a lack of understanding of the effects of psychosocial factors. Using data from previous research, this study aimed to better define the role of physical activity and FV intake in short- and long-term weight loss via changes in malleable psychosocial mediators and moderators.

METHODS

Women who were obese ( = 183; age = 50.0 ± 7.9 years; body mass index = 35.2 ± 3.2 kg/m, mean ± SD) and who previously participated in 3 different community-based behavioral weight-loss treatments were assessed over 2 years. Changes in FV intake, physical activity, self-regulation of physical activity and eating (aggregated), negative mood, and weight were measured over 6 and 24 months.

RESULTS

Changes in each variable over both 6 and 24 months were significant (all values <0.001). The FV intake to the weight-related caloric intake relationship (β = -0.30, < 0.001) was significantly mediated by self-regulation change over 6 months. The physical activity to weight-change relationship (β = -0.46, < 0.001) was significantly mediated by both self-regulation and mood change over 24 months. Physical activity, itself, accounted for only 16% of weight-related caloric expenditure differences. Changes in physical activity and FV intake were each independent predictors of weight change over 24 months (overall  = 0.50, < 0.001).

CONCLUSION

Findings clarified theory-based targets for weight-management treatments and suggested that future weight-loss treatments strongly focus on developing self-regulatory skills to address barriers to behavioral changes.