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.

There is increasing evidence that patients who have problems with binge eating (BE) or BE disorder (BED) are quite common among the severely obese, including bariatric surgery candidates. The literature suggests that in many cases such eating behaviours improve after bariatric surgery, although this is not uniformly true. The current paper reviews the data on the development of BE, BED and loss of control (LOC) eating after bariatric surgery and the impact of these problems on long-term weight outcome. A search was made of various databases regarding evidence of BE, BED and LOC eating post-operatively in bariatric surgery patients. The data extracted from the literature suggests that 15 research studies have now examined this question. Fourteen of the available 15 studies suggest that the development of problems with BE, BED or LOC eating post-bariatric surgery is associated with less weight loss and/or more weight regain post-bariatric surgery. These data suggests that it is important to identify individuals at high risk for these problems, to follow them post-operatively, and, if appropriate interventions can be developed if such behaviours occur in order to maximize weight loss outcomes.

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