Is gallstone disease caused by obesity or by dieting?

The effects of dieting and obesity on the risk of acute gallstone disease were evaluated in a case-control study in Maastricht, The Netherlands, during 1983-1986. The study comprised 151 cases with acutely symptomatic gallstone disease and 451 population controls. The effects of dieting and obesity as measured by body mass index (weight (kg)/height (m)2) were disentangled in a multivariate logistic regression analysis. Both dieting and body mass index were positively associated with the rate of gallstone disease. The association with dieting largely disappeared when initial body mass index was controlled for (rate ratio = 1.4, 95% confidence interval 0.8-2.4). Conversely, controlling for dieting did not affect the association between body mass index and gallstone disease. Analysis by risk period (year 1 and 2-5, 6-10, and 11-15 years prior to interview) did not show consistent risk period-specific effects when initial body mass index was controlled for. The authors conclude that dieting does not account for the association between obesity and gallstone disease. In obese persons, dieting does not increase the risk of acute gallstone disease over the long term.