The studies in this thesis were aimed at examining cognitive and emotional factors that predict or obstruct a successful weight outcome after bariatric surgery (weight loss surgery) for morbid obesity. The thesis includes two studies with a cross-sectional and four studies with a prospective design. The models of assessment used were semi-structured interviews, self-report questionnaires, and actual weight and height measurements, with repeated assessments taken six months before, and six months, one year, and each next year after operation. Before the operation, self regulation cognitions of patients reflected a helpless and pessimistic state. Female patients with morbid obesity showed before operation less positive and more negative affect, more difficulty identifying feelings, and more suppression of emotions than women from the general population. Both worse affect and the unhealthy processing of emotions were reported to be associated with emotional eating. Regarding pre-post differences, virtually all variables, including the psychological, reflected a severely worse state before, than after bariatric surgery. This indicates that bariatric surgery not only accomplishes weight loss and a reduction of co-morbidity, but also changes in well-being and cognitions. A premise of this thesis was that the appropriate tools to improve the outcome of bariatric surgery could be found by examining cognitive and emotional factors that impact on eating behavior of patients after bariatric surgery. However, the results indicate that most of the cognitive or emotional factors measured did not predict the post-surgical weight outcome. Aspects of self-regulation, outcome expectations, and satisfaction were not associated with weight-loss outcome after the operation. The only possible predictor found for more weight loss in the long-term was a lower mental quality of life. Patients with a lower mental quality of life preoperatively or short-term postoperatively had a better weight loss outcome in the long-term. With respect to clinical implications, the most important issue is whether our findings can be used to improve intake screening and long-term weight loss outcome after bariatric surgery. That operatively induced effects of weight loss after bariatric surgery appear to be achieved independently of preoperative self-regulation cognitions, outcome expectations, and satisfaction implies that preoperative psychological variables cannot be used as intake screening or gatekeeper to indicate who will achieve a good weight outcome, needs additional counseling, or should be selected for surgery. The finding that patients with a higher preoperative and postoperative mental quality of life are at risk for a poorer long-term weight outcome suggests that the bariatric team should be aware that this specific group may need help in postoperative weight loss management.
