Relationship among Self-Efficacy Expectations, Locus of Control, and Attributions in Bariatric Patients.

Background: Bariatric surgery is the most effective method for achieving accelerated weight loss. However, in the short- and medium-term, between 20% and 40% of patients regain a significant percentage of the weight lost. Cognitive and attitudinal psychological variables contribute to explaining weight regain. The aim of this study was to analyze differences in self-efficacy, locus of control, and attributions among bariatric patients, in accordance with weight maintenance or weight regain. Methods: Participants were classified according to weight regain (≥15% weight regain) and weight maintenance (<15% weight regain). A receiver operating characteristic (ROC) curve analysis was employed to assess the diagnostic value of the locus of control for weight loss and to establish a cutoff point to differentiate those who maintained weight loss from those who regained more than 15% of the weight lost. Results: Those who maintained weight loss showed a statistically higher locus of control ratio than those who regained weight. The locus of control ratio was associated with a lower risk of weight regain (odds ratio 0.760, p = 0.018). Using the area under the ROC curve (AUC), the locus of control significantly identified those who maintained weight (AUC = 0.761; p = 0.001). The maximum combination of sensitivity and specificity was shown at the cutoff point of 39. Qualitative results show a difference in the type of attributions and expectations according to current weight maintenance or weight regain status. Conclusion: Participants’ self-efficacy expectations, locus of control, and attributions change in accordance with the outcome achieved in terms of weight regain or weight maintenance.