Women with a high body mass index (BMI) are at an increased risk of developing gallstones, a new study indicates.

Gallstones are small, pebble-like substances that develop in the gallbladder, often as a result of excess cholesterol. The function of the gallbladder is to store bile, a digestive juice produced by the liver. Bile is required to digest a fatty meal.

Gallstones are very common, although only around 30% of those affected will go on to develop symptoms or complications, such as pain, recurring indigestion and jaundice.

While previous research has found a link between gallstones and BMI, until now, it was unclear whether having a high BMI could actually cause them.

Danish scientists decided to investigate this further. They looked at more than 77,000 over a 34-year period, during which time, over 4,000 of the participants developed symptomatic gallstone disease.

The study found that those who developed gallstones were more likely to be female, older and less physically active.

It also found that women with a high BMI were almost three times more likely to develop gallstones that those with a healthy BMI.

"Obesity is a known risk factor for gallstone disease and our study suggests that elevated BMI likely contributes to the development of this disease. These data confirm that obesity adversely affects health, and lifestyle interventions that promote weight loss in overweight and obese individuals are warranted," the team from Copenhagen University Hospital said.

Details of these findings are published in the journal, Hepatology.