Objective: To investigate changes in neural activation and desire to eat in response to appetitive cues from pre- to postbariatric surgery for obesity. Background: Roux-en-Y gastric bypass (RYGB) is the most common bariatric procedure. However, the mechanisms of action in RYGB are not well understood. A significant proportion of the resulting reduction in caloric intake is unaccounted for by the restrictive and malabsorptive mechanisms and is thought to be mediated by neuroendocrine function. Numerous investigations of postsurgical changes in gut peptides have resulted; however, changes in neural activation after RYGB surgery have not been previously investigated. METHODS: Functional magnetic resonance imaging and verbal rating scales were used to assess brain activation and desire to eat in response to high- and low-calorie food cues in 10 female patients 1-month pre- and post-RYGB surgery. Results: Postsurgical reductions in brain activation were found in key areas within the mesolimbic reward pathway, which were significantly more pronounced in response to food cues that were high (vs. low) in caloric density. These changes mirrored concurrent postsurgical reductions in desire to eat, which were also greater in response to food cues that were high versus low in caloric density (P = 0.007). Conclusions: Findings support the contention that RYGB surgery leads to substantial changes in neural responses to food cues encountered in the environment, provide a potential mechanism for the selective reduction in preferences for high-calorie foods, and suggest partial neural mediation of changes in caloric intake seen after RYGB surgery.

Accumulating evidence suggests that bariatric surgery candidates are likely to present with eating disorders (EDs) and/or problematic eating behaviours (EBs), and research suggests that these problems may persist or develop after bariatric surgery. While there is growing evidence indicating that EDs and EBs may impact bariatric surgery outcomes, the definitions and assessment methods used lack consensus, and findings have been mixed. The aims of this paper were (1) to summarize the existing literature on pre‐operative and post‐operative EDs and problematic EBs; (2) to discuss the terms, definitions and assessment measures used across studies; and (3) to consider the extent to which the presence of these problems impact surgery outcomes. We highlight the importance of investigators utilizing consistent definitions and assessment methodologies across studies. © 2015 The Authors. European Eating Disorders Review published by Eating Disorders Association and John Wiley & Sons Ltd.