Feeding behavior and body weight development: lessons from rats subjected to gastric bypass surgery or high-fat diet.

Weight loss treatments include diets, drugs, physical training, and surgery, namely bariatric or obesity surgery. The current standard for bariatric surgery is gastric bypass. There are common beliefs that gastric bypass induces body weight loss because of a reduced food intake and that high-fat diet induces overweight and obesity because of overnutrition. The principal aim of the studies on rats summarized herein was to better understand the physiological mechanisms by which gastric bypass achieves body weight loss and by which high-fat diet induces obesity. The results indicated that gastric bypass efficiently reduced body weight, particularly the fat compartment, which was unlikely to be caused by early satiety, reduced food intake or malabsorption, and that large meal size, but not overnutrition, was mainly responsible for high-fat diet-induced obesity. It was unclear whether gastric ghrelin, obestatin and/or amine in the A-like cells were involved in this context.