<p>Background: Bariatric surgery produces marked weight loss and improvement in comorbid health conditions among individuals with Class II or Class III obesity (Class I = 30.0 &le; BMI &le; 34.9kg/m2; Class II = 35.0 &le; BMI &ge; 39.9kg/m2; Class III = BMI &ge; 40 kg/m2). However, suboptimal weight outcomes occur in a significant minority of patients. Evidence suggests that psychological and behavioral factors might affect weight loss, but most of the literature has focused on preoperative factors, with mixed results. The current study tested the hypothesis that postoperative depressive symptoms, eating behaviors, and lower levels of physical activity would be associated with poorer weight loss outcomes. Method: Preoperative data were obtained from an extant clinical database, and postoperative data were collected via a mail or online questionnaire in a sample of 141 female Roux-en-y gastric bypass (RYGB) patients at an average of 16.80 (SD=2.20) months post-surgery. Self-report measures assessed cognitive-affective and somatic symptoms of depression; binge eating, grazing, night eating, distress about overeating or loss of control over eating; and physical activity. Results: Weight outcome measures were defined as percentage of excess BMI loss (%EBMIL) and successful weight loss (&ge; 50% EBMIL). Higher distress was associated with poorer %EBMIL, and higher level of physical activity was associated with greater %EBMIL. Decreased cognitive-affective symptoms and increased somatic symptoms of depression were associated with a higher probability of successful weight loss. Increased somatic complaints predicted greater %EBMIL unless those symptoms were associated with higher sedentary behavior. Conclusions: Consistent with hypotheses, preoperative depressive symptoms and binge eating disorder did not predict weight loss. Aspects of all three postoperative domains were associated with weight outcomes. Future research should explore the relations among these psychological and behavioral factors and weight loss over a longer follow-up period.</p> / Dissertation