In the developed world, gallstone disease is the most common abdominal illness requiring admission to hospital. And in the USA, more than 800,000 operations to remove gallstones are carried out every year. Most gallstones are nuggets of cholesterol.
The findings are based on comprehensive two yearly monitoring of more than 42,000 women in the United States, who were part of the Nurses Health Study.
The women were all aged between 39 and 66 in 1986, when the gallstone study began. None of the women had gallstones. All provided waist and hip measurements and details of their normal diet.
During the subsequent monitoring period to the year 2000, 3197 women required gallstone surgery.
After taking into account total body fat distribution as well as other risk factors for gallstone disease, women with waists of 36 inches or more were almost twice as likely to require surgery to remove gallstones as those whose waists measured 26 inches or less.
Waist to hip ratio, which divides the waist size by hip size, also boosted the risk by around 40% among women with a ratio of 0.86 compared with those whose ratio was 0.70 or less.
These results held true even if a woman was not generally overweight, as determined by body mass index.
The authors suggest that there are plausible biological explanations for a link between gallstones and the midriff bulge. The type of fat around the waist is more metabolically active than fat elsewhere on the body.
And previous research has also linked gallstones with the metabolic syndrome, a feature of which is excess abdominal fat.
Journal
Gut