Gallstones in obesity and weight loss

The prevalence of cholesterol gallstones is increased in obese persons, The risk is especially high in those with the highest body mass index (relativ e risk 5-6), Weight loss further increases the risk of gallstones: the prev alence of new gallstones reaches 10-12% after 8-16 weeks of low-calorie die t and more than 30% within 12-18 months after gastric by-pass surgery. Abou t one-third of the stones are symptomatic. The increased prevalence of ston es is mostly due to supersaturation of bile with cholesterol, because of an increased synthesis by the liver and secretion into bile. Saturation is fu rther increased during weight loss. It returns toward normal after weight s tabilization at a lower level, allowing spontaneous stone dissolution in so me cases, Identified risk factors for gallstones during weight loss are a r elative loss of weight greater than 24% of initial body weight, a rate of w eight loss greater than 1.5 kg per week, a very low calorie diet with no fa t, a long overnight fast period and a high serum triglyceride level. Ursode oxycholic acid decreases cholesterol saturation of bile and gallstone incid ence during weight loss, Other preventive measures include a control of wei ght loss rate, a reduction of the length of overnight fast, and maintenance of a small amount of fat in the diet Eur J Gastroenterol Hepatol 12:1347-1 352 (C) 2000 Lippincott Williams & Wilkins.