Bile is produced by the liver and stored in the gallbladder. It consists of bilirubin (a product of the breakdown of hemoglobin, a component of red blood cells), bile salts, fatty acids, cholesterol and other chemicals. Dietary fat in the upper part of the small intestine stimulates the gallbladder to release bile. When cholesterol becomes concentrated and crystallizes in the bile, gallstones may form.
Gallstones are more common in overweight women. Even being moderately overweight increases one's risk of developing gallstones. In fact, obese women 20 to 30 years of age have a sixfold increase in the risk of gallbladder disease compared with women of normal weight.
The precise reason why being overweight causes gallstones is unclear. Scientists believe that being overweight leads to gallstone formation because of excess cholesterol production (which upsets the balance in the bile) and because obesity decreases the gallbladder's ability to contract.
Undergoing rapid or extreme weight loss also increases the risk of developing gallstones. Dieting alters the cholesterol-bile salt balance in favor of gallstone formation, and skipping meals decreases the contractions of the gallbladder.
The most commonly recommended dietary treatment is moderation: Eat healthy, well-balanced, low-fat meals. If you need to lose weight, do it gradually; and if you already suffer from gallstones, see your doctor before starting a weight-loss program.