Background: Attempts to understand postoperative psychosocial changes in the lives of individuals who have undergone gastric bypass surgery for morbid obesity have 1) been guided by constructs emanating from the assumptions of researchers, and 2) have resulted in fragmented conclusions that catalogue changes without theoretically integrating them. Materials and Methods: Using unstructured and semi-structured interviews and in-depth focus groups, 31 patients were asked in an open-ended fashion about the ways, if any, in which gastric bypass surgery had affected their lives. Grounded theory methodology was utilized in order to identify emergent themes and their interrelations, and build a meaningful, comprehensive theory of life after gastric bypass. Results: Patients' report of a rebirth/transformation was identified as the core process of the theory. The changes marking this process were clearly conceptualized in dichotomous terms comparing pre to postsurgical life. Patients reported changes that they regarded as unequivocally positive, a number of which had not been previously reported in the literature. Unique to this particular study was the finding of numerous life changes that generated tension and posed challenges in various aspects of patients' lives. Conclusion: The grounded theory proposes that the extent to which patients successfully negotiate tension-generating changes may be a major determinant in the long-term outcome of gastric bypass, both weight loss and psychosocial adjustment.