Central fat, as measured by abdominal circumference or waist-to-hip ratio, is associated with an increased risk of gallbladder removal or “cholecystectomy” among women, researchers at Harvard Medical School report. By far the most common reason for this surgery is the presence of gallstones.

Although other studies have suggested a link between belly fat and gallstones, they were limited by short follow-up periods or other design issues, lead investigator Dr. C-J Tsai and colleagues note.

They therefore examined the association using data from the prospective Nurses’ Health Study. Included were 42,312 women ages 39 to 66 years in 1986, when they were asked to measure their waist at the level of the belly button and their hips at the largest circumference. The subjects were followed up biennially to see if they had undergone cholecystectomy.

According to their report in the medical journal Gut, the Boston-based researchers documented 3197 cases of cholecystectomy during several years of follow-up.

The authors found that women with a waist-to-hip ratio of 0.86 or higher were nearly twice as likely to undergo cholecystectomy as were women with a ratio of less than 0.70. Similarly, a waist circumference of 36 inches or more raised the risk of this surgery by 3.4-fold relative to a circumference of less than 26 inches.

Tsai’s group suggests that there are plausible biological reasons why belly fat could cause gallstones to form. Such fat could indirectly affect the composition of bile, making it more likely to form stones, they explain.

“Both waist-to-hip ratio and waist circumference are relatively easy to obtain and appear to impart clinically useful information regarding risk of gall stone disease,” they conclude.

SOURCE: Gut, February 2006.