The study included 24,729 men aged 40–75 who provided baseline information about the number of intentional weight loss episodes between 1988 and 1992 and the amount of weight lost during each episode.
Between 1992 and 2002 the participants were assessed for symptoms of gallstones at two-year intervals.
BMI was controlled in the analysis to account for the possibility that the impact of yo-yo dieting might differ with height and body weight. It was found that 1,222 men developed symptomatic gallstones.
Men who had experienced the largest weight loss of 9.1kg or more had the highest incidence of gallstones.
The risk for gallstones increased in men who repeatedly lost and regained weight.
Compared with men who had a steady weight, those who had two or more weight fluctuations of 4.5 to 8.6kg, had a 30 per cent increased risk of gallstones.
Men whose weight fluctuated by more than 9.1kg had a 50 per cent increased risk.
This could be because of the accumulation of body fat and the development of metabolic abnormalities that occur during weight loss.
Serum leptin levels and insulin levels were found to be significantly higher in yo-yo dieters then in weight maintainers.
This suggests that these increased levels of leptin and insulin may also contribute to gallstone risk.