Zucker fafa rats maintain their obese body composition ten months after jejunoileal bypass surgery.

In order to evaluate the long-term effects of intestinal bypass surgery in an animal model of early onset hypercellular-hypertrophic obesity, adult female obese and lean Zucker rats were given jejunoileal bypass surgery or sham operations. At sacrifice ten months post-surgery, body weights of obese bypass rats were nearly reduced to lean bypass levels. This reduction in body weight was not accompanied by normalization of body composition or of the hyperinsulinemia and hypertriglyceridemia characteristic of this obese syndrome. Obese bypass rats maintained 44 percent of their weight as lipid compared to 12 percent in lean bypass rats and 15 percent in sham-operated lean rats. In addition, obese bypass rats maintained elevated adipose tissue lipoprotein lipase activity and increased fat cell size and were hyperinsulinemic and hypertriglyceridemic. Furthermore, obese bypass rats had reduced carcass protein and reduced weight and DNA and/or protein contents in heart, liver, muscle and kidney. Therefore, although bypass surgery resulted in significant weight loss, it did not normalize the obese syndrome and may result in serious reductions in the weight and cellularity of vital organs.