Gastric bypass increases ethanol and water consumption in diet-induced obese rats

Background: Roux-en-Y gastric bypass surgery (RYGB) is an effective treatment for morbid obesity. Increased alcohol abuse after RYGB resulted in recommendations to exclude patients with alcohol abuse histories from RYGB. The purpose of our study was to examine the effects of a RYGB on ethanol intake in diet-induced obese rats (high-fat diet). Methods: The animals underwent RYGB and were habituated along with their sham-operated obese controls and with lean rats to increasing concentrations of ethanol in a two-bottle choice paradigm. Results: RYGB rats' daily consumption of ethanol averaged 2 g/kg at 2 % habituation and 3.8 g/kg at 4 % habituation, twice as much as sham-operated obese controls and 50 % more than normal-diet lean controls. Obese controls drank on average 1 g/kg of ethanol (2 and 4 %), significantly less (50 %) than lean controls did. RYGB rats when given higher ethanol concentrations (6 and 8 %) or no ethanol drank significantly more water than lean and obese controls did (66 and 100 %, respectively), and their enhanced total fluid intake was associated with increased food intake, which was significantly higher than in lean (66 % more calories; food + alcohol) and obese controls (44 % more calories). The lower alcohol intake in the obese controls than in the lean rats suggests that obesity may interfere with alcohol's rewarding effects and RYGB may remove this protective effect. Conclusions: The overall enhancement of consummatory behaviors (both ethanol and water) suggests that RYGB may facilitate alcohol consumption, which in vulnerable individuals could lead to abuse and addiction.