Hepatobiliary effects of obesity and weight-reducing surgery.

Obesity clearly increases the risk of gallstone formation. The role of nucleating factors may be most decisive in transforming merely saturated bile into a gallstone-forming solution. Weight loss in the short run may promote stone formation but in the long run may be beneficial if it is maintained. UDCA appears to be a promising prophylactic agent against gallstone formation during weight loss regardless of whether it is achieved by diet alone, by jejunoileal bypass, or by gastric restriction surgery.