Bariatric surgery is the most effective and durable treatment for severe obesity. Eating disorders and eating pathology are common both pre- and post-operatively in this population. Unfortunately, research is stymied by a lack of appropriate assessments, targeted treatments and an understanding of how the biological aspects of surgery may impact eating behavior (e.g., microbiome). This symposium will provide an overview of the bio-behavioral underpinnings of disordered eating among patients with severe obesity and bariatric surgery and discuss ongoing trials examining predictors of outcomes and treatment for disordered eating in bariatric surgery populations.Moderator: James Mitchell, MD; University of North Dakota School of MedicineTitle of First Talk: Bariatric Surgery and Eating Behavior: Overview of Mechanisms of Action and Challenges to Our UnderstandingSpeaker: Leslie Heinberg, PhD; Cleveland Clinic Lerner College of MedicineTitle of Second Talk: Relationships between the Gut Microbiome, Body Weight, and PsychopathologySpeaker: Kristine Steffen, PhD, PharmD. North Dakota State UniversityTitle of Third Talk: A Randomized Controlled Trial of Treatments for Loss-of-Control Eating Following Bariatric Surgery: 12-month follow-up (Carlos M. Grilo, Valentina Ivezaj, Andrew J. Duffy, & Ralitza Gueorguieva)Speaker Name: Valentina Ivezaj, PhD; Yale School of Medicine