Changes in Food Preference and Taste Responses after Roux-en-Y Gastric Bypass

Abstract

Currently, the most powerful therapy for obesity is bariatric surgery both in terms of significant weight loss and long-term efficacy. Most surgeons regard the Roux-en-Y gastric bypass (gastric bypass) operation as “gold standard” for obesity treatment. However, underlying mechanisms by which gastric bypass induces and sustains weight loss are not fully understood, but include reduced hunger, increased satiety, increased energy expenditure, altered taste, as well as reduced preference for foods with a high fat and sugar content. In fact, gastric patients often report idiosyncratic changes in taste perception that involves “sweet” taste and a calorie-dense food. I herein aimed to investigate how gastric bypass reduces intake of and preference for food high in fat and sugar in rats and humans. I found that the proportion of dietary fat in gastric bypass patients was significantly reduced six years after surgery compared with patients after vertical-banded gastroplasty. In addition, gastric bypass patients had an increased sucrose detection sensitivity compared with before surgery and controls, but hedonic taste ratings of sucrose in bypass patients remained unchanged. Rats after gastric bypass exhibit a shift away from high to low fat food. When compared to sham-operated rats, gastric bypass rats did not prefer high sucrose and fat concentrations in a two bottle preference test, but preoperative sucrose exposure reduced this effect. There was no difference in appetitive or consumatory behaviour in the brief access test between the sham-operated and gastric bypass rats. An oral gavage of 1 ml corn oil in gastric bypass rats induced conditioned taste aversion which was also demonstrated after exogenous administration of the GLP-1 receptor agonist exendin-4 (2 μg/kg intraperitoneal) in unoperated rats. These findings suggest that an altered food preference may contribute to long-term maintained weight loss after gastric bypass. Postingestive effects resulting in conditioned taste aversion may partially explain this observation.