Abstract

Roux-en-Y Gastric bypass is the most effective therapy for morbid obesity. This study investigated how gastric bypass affects intake of and preference for high fat food in an experimental (rats) study and within a trial setting (humans). Proportion of dietary fat in gastric bypass patients was significantly lower six years after surgery compared with patients after vertical-banded gastroplasty (p=0.046). Gastric bypass reduced total fat and caloric intake (p<0.001) and increased standard low fat chow consumption in comparison to sham controls (p<0.001) in rats. When compared to sham-operated rats, gastric bypass rats displayed much lower preferences for Intralipid® concentrations above 0.5% in an ascending concentration series (0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 5%) of two bottle preference tests (p=0.005). This effect was demonstrated 10 and 200 days after surgery. However, there was no difference in appetitive or consummatory behaviour in the brief access test between the two groups (p=0.71) using similar Intralipid® concentrations (0.005% through 5%). Levels of Glucagon-like peptide-1 (GLP-1) were increased after gastric bypass as expected. An oral gavage of 1 ml corn oil after saccharin ingestion in gastric bypass rats induced a conditioned taste aversion. These findings suggest that changes in fat preference may contribute to long-term maintained weight loss after gastric bypass. Postingestive effects of high fat nutrients resulting in conditioned taste aversion may partially explain this observation; the role of GLP-1 in mediating postprandial responses after gastric bypass requires further investigation.