Risk Factors for Gallstones

Risk factor list: The list of risk factors mentioned for Gallstones in various sources includes:

• Age - especially over 60
• Obesity
• Dieting
• Gastric bypass surgery - stomach reduction surgery
• Race - High risk for Native Americans
• Native Americans
• Pima Indians
• Mexican-Americans
• Gender - women twice as likely
• Cholesterol-lowering drugs
• Diabetes
• Rapid weight loss
• Fasting

Risk factors discussion: Overweight people are at greater risk of developing gallstones that people of average weight. However, people who are considering a diet program requiring very low intake of calories each day should be aware that during rapid or substantial weight loss, a person's risk of developing gallstones is increased. ¹

Why obesity is a risk factor for gallstones is unclear. But researchers believe that in obese people, the liver produces too much cholesterol. The excess cholesterol leads to supersaturation in the gallbladder. ¹

People who lose a lot of weight rapidly are at greater risk for developing gallstones. Gallstones are one of the most medically important complications of voluntary weight loss. The relationship of dieting to gallstones has only recently received attention.

One major study found that women who lost from 9 to 22 pounds (over a 2-year period) were 44 percent more likely to develop gallstones than women who did not lose weight. Women who lost more than 22 pounds were almost twice as likely to develop gallstones.

Other studies have shown that 10 to 25 percent of obese people develop gallstones while on a very-low-calorie diet. (Very-low-calorie diets are usually defined as diets containing 800 calories a day or less. The food is often in liquid form and taken for a prolonged period, typically 12 to 16 weeks.) The gallstones that developed in people on very-low-calorie diets were usually silent and did not produce any symptoms. However, about a third of the dieters who developed gallstones did have symptoms, and a proportion of these required gallbladder surgery.

In short, the likelihood of a person developing symptomatic gallstones during or shortly after rapid weight loss is about 4 to 6 percent. This estimate is based on reviewing just a few clinical studies, however, and is not conclusive.¹

Researchers believe dieting may cause a shift in the balance of bile salts and cholesterol in the gallbladder. The cholesterol level is increased and the amount of bile salts is decreased. Going for long periods without eating (skipping breakfast, for example), a common practice among dieters, also may decrease gallbladder contractions. If the gallbladder does not contract often enough to empty out the bile, gallstones may form. ¹

Gallstones are common among obese patients who lose weight rapidly after gastric bypass surgery. (In gastric bypass surgery, the size of the stomach is reduced, preventing the person from overeating.)

One study found that more than a third (38 percent) of patients who had gastric bypass surgery developed gallstones afterward. Gallstones are most likely to occur within the first few months after surgery.¹

Several studies suggest that smoking may increase the risk of developing gallstones and that the risk may be higher for women. However, research results on this topic are not consistent, and more study is needed. ²

Risk factors for gallstones include obesity ; a large clinical study showed that being even moderately overweight increases one's risk for developing gallstones. This is probably true because obesity tends to cause excess cholesterol in bile, low bile salts, and decreased gallbladder emptying. Very low calorie, rapid weight-loss diets, and prolonged fasting, seem to also cause gallstone formation.

No clear relationship has been proven between diet and gallstone formation. However, low-fiber, high-cholesterol, high protein diets, and diets high in starchy foods have been suggested as contributing to gallstone formation.³

Those who are most likely to develop gallstones are:

• Women between 20 and 60 years of age. They are twice as likely to develop gallstones than men.

• Men and women over age 60.

• Pregnant women or women who have used birth control pills or estrogen replacement therapy.

• Native Americans. They have the highest prevalence of gallstones in the United States. A majority of Native American men have gallstones by age 60. Among the Pima Indians of Arizona, 70 percent of women have gallstones by age 30.

• Mexican-American men and women of all ages.

• Men and women who are overweight.

• People who go on "crash" diets or who lose a lot of weight quickly.

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