Individuals who are overweight and lose weight rapidly have an increased risk of developing gallstones. Dieters who lose more than three pounds per week are at higher risk compared to dieters who lose weight at a slower rate.
The normal function of the gallbladder, which is a small sac located below the liver, is to store bile until it is needed. Bile helps the body digest fat. Produced by the liver, bile is stored in the gallbladder. During the process of digestion, the gallbladder contracts, pushes bile through the common bile duct, and into the small intestines.
Gallstones are hard deposits that form within the gallbladder when substances in bile, mainly cholesterol, bile pigments, and calcium salts, become overly concentrated. Gallstones can be as small as a grain of sand or the size of a golf ball. A large stone can obstruct the common bile duct and cause symptoms. Some individuals can be asymptomatic (without symptoms). The most common symptoms are pain in the right upper or middle upper abdomen, fever, and jaundice (yellow coloring of the skin and the whites of the eye). A person may experience abdominal fullness, clay-colored stools, nausea and vomiting (1).
One cause of gallstones or cholethiasis is the alteration in fat metabolism during periods of prolonged fasting or rapid weight loss. According to an article in the November 1993 issue of the Annals of Internal Medicine, 10 to 25 percent of people on a very low-calorie diet (VLCD) developed gallstones. A VLCD usually allows 800 calories daily in food or liquid form for 12 to 16 weeks. About one third of the VLCD dieters who developed gallstones had symptoms and some required gallbladder surgery (2). Experts think that the liver secretes more cholesterol into bile in response to the VLCD. The gallbladder does not empty properly and gallstones form (3).
Weight-cycling, which is the process of losing and gaining weight rapidly, increases the risk of developing gallstones, Individuals, with losses and gains of 10 pounds or more, have a higher risk of developing gallstones compared to individuals who lost weight and maintained the weight loss.