Purpose: This study evaluated the effectiveness of three behaviorally based weight loss treatments on long term (6 month) weight maintenance following an 8 week intervention. The main focus of this study was to evaluate the impact of psychosocial factors (self-efficacy and social support) on the maintenance of weight loss in obese adults following a randomized weight loss trial. Currently, there is a need for more psychological theory-based weight loss interventions to identify the most effective methods for sustained behavior change. Self-efficacy has been identified as a key component of successful weight loss. Social support has been shown in the literature to have a positive impact on weight loss, but the relationship between social support and weight loss maintenance is unclear.

Methods: This study was a 6 month follow-up (4 months post-intervention) to an 8 week weight loss intervention. Participants (n = 109) were recruited in two cohorts (Fall and Spring) and randomized into one of three treatments: 1) guided weight loss support, 2) self-monitoring tool, or 3) guided support and self-monitoring tool. Of the 78 participants that completed the 8 week intervention, 53 returned for the 6 month follow-up. Anthropometric measures (height, weight, BMI, body fat, waist circumference) and responses to self-efficacy surveys (diet and physical activity) were collected at baseline, 8 weeks, and 6 months. Participants also completed surveys evaluating perceived social support from family and friends for health behaviors (eating habits and physical activity) at 6 months.

Results: Overall, there was good retention of weight loss with average weight loss retention of 4.82 kg (SD = 4.83) over the 6 months. Approximately half (47%) of the participants were able to maintain weight loss over the 6 month follow-up. There were no significant differences in weight loss or other anthropometric outcomes between cohorts, treatment groups, or genders; which may have been due to small sample size. Correlations between self-efficacy and weight outcomes did not achieve statistical significance at the p < .05 level, but they approached significance and were negatively correlated, but the magnitudes of the correlations were weak. Although associations between social support and weight change were not significant, social support for physical activity and from friends was moderately correlated with diet self-efficacy at 6 months. A relationship which may be important, as significant differences in 6 month diet self-efficacy were found among participants that maintained significant weight loss (>5% loss of baseline body weight) versus those that did not maintain significant weight loss. The results showed a tendency for self-efficacy and social support to be higher among participants that successfully retained weight loss versus participants that regained weight.

Conclusions: All treatment groups experienced positive changes in anthropometric outcomes, but identification of specific behavioral processes that may influence weight maintenance proved difficult. Future research should focus on identifying techniques to maintain higher levels of self-efficacy post-intervention. More research is needed to determine the effects of social support on specific weight related behaviors and self-efficacy for weight related behaviors.