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Obesity has become a major public health problem in Western societies. Although surgery is considered the treatment of choice in morbid obesity, the outcome is variable and weight regain may occur in the long-term postoperative period. The aim of this thesis was to examine psychological predictors of treatment outcome after Laparoscopic adjustable gastric banding (LAGB) for morbid obesity. LAGB is a purely restrictive form of bariatric surgery designed to induce weight loss by limiting food consumption. The thesis consists of seven studies (five cross-sectional and two prospective), which are described in three parts: psychosocial outcome (chapter 2), general psychological predictors (chapters 3 and 4), and specific behavioral predictors and related determinants (chapters 5, 6, 7, and 8). The main aim of chapter 2 was to examine the short-term and long-term physical, mental, and particularly social quality of life in patient with severe obesity following LAGB. It was concluded that, in comparison with patients before surgery, patients after surgery felt and functioned better on physical and psychological dimensions of quality of life, and on most aspects of social quality of life. The purpose of the prospective study in chapter 3 was to examine whether personality traits predict short-term weight loss and, specifically, long-term weight loss maintenance after LAGB. Chapter 4 cross-sectionally examined the relationship between reported childhood sexual abuse and weight and health outcome after LAGB. The results in this thesis show that the general psychological predictors personality characteristics and childhood sexual abuse are not major predictors of outcome after bariatric surgery. Chapter 5 cross-sectionally analyzed binge eating and eating characteristics of a relatively large patient group with both short- and long follow-up duration after LAGB, while chapter 6 prospectively analyzed preoperative binge eating behavior and depression as predictors of weight outcome relatively short-term after LAGB. Our prospective study shows that preoperative binge eating, depression, and combined binge eating and depression, did not predict a worse weight outcome after LAGB. However, postoperative binge eating was associated with a worse weight outcome. Moreover, in chapter 7 binge eating was indicated to be a possible mediator between eating attitudes and weight and mental health outcome, whereas physical exercise was not a crucial mediator between exercise beliefs and outcome. Finally, chapter 8, focusing on cortisol and binge eating, shows that no differences in morning cortisol levels between patients with and without binge eating disorder were found, however, patients with binge eating disorder had lower total daytime cortisol levels than patients without binge eating disorder, and the magnitude of this difference was large. In conclusion, in terms of the predictive strength of postoperative outcome from preoperative psychosocial factors, this thesis provides no reason to exclude specific subgroups of morbidly obese patients from the operation or to give additional preoperative psychosocial care to specific subgroups of patients. Instead, the findings of this thesis suggest that the identification of individual patients requiring extra psychosocial care could better take place after the operation, with attention focused upon patients with binge eating problems.

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.