Alcohol consumption promotes insulin sensitivity without affecting body fat levels

Objective: Alcohol consumption promotes insulin sensitivity. In obesity, a decrease in body fat levels decreases the risk of developing insulin resistance; therefore, it is possible that alcohol improves insulin sensitivity by negatively affecting body fat. The aim of this study was to determine whether alcohol consumption promotes insulin sensitivity by reducing body fat levels in C57BL/6 male mice. Methods: We examined the effects of alcohol consumption on insulin sensitivity in male mice with three different body weight (BW) phenotypes. The BWs were induced by feeding the mice a 30% calorie-restricted (CR) regimen, a low-fat (LF) diet and a high-fat (HF) diet. The mice had free access to water or 20% ethanol in the drinking water. To determine the effects of the three different BW phenotypes and of alcohol on glucose regulation and insulin sensitivity, we performed the insulin tolerance test (ITT) and glucose tolerance test (GTT) on the mice. The effects of the diets and alcohol on body composition, percent body fat (% BF), percent lean mass and bone mineral density (BMD) were determined by dual-energy X-ray absorptiometry (DEXA). Results: Data show that mice with the highest body fat levels (HF) were insulin resistant and glucose intolerant. In contrast, mice with the lowest body fat levels (CR) were the most insulin sensitive and cleared the injected endogenous glucose the fastest. Results show that alcohol did not affect GTT in any of the BW phenotypes. However, alcohol consumption promoted insulin sensitivity in mice consuming both the LF and HF diets. Alcohol consumption increased insulin sensitivity without affecting body fat levels, as body fat levels were similar in mice consuming the LF or HF diets and drinking either water or alcohol. Conclusions: Alcohol consumption promotes insulin sensitivity without affecting body fat levels in mice consuming LF and HF diets.