Background & Aims The prevalence of gallstones is increasing in association with the obesity epidemic, but rapid weight loss also increases the risk of stone formation. We conducted a systematic review of the efficacy of strategies to prevent gallbladder stones in adults as they lose weight.

Methods Randomized controlled trials of nonsurgical strategies to prevent gallstones were identified by electronic and manual searches. Our final analysis included 13 trials, comprising 1836 participants undergoing weight loss through dieting (8 trials) or bariatric surgery (5 trials). The trials compared ursodeoxycholic acid (UDCA) or high-fat weight loss diets with control interventions. We performed random-effects meta-analyses and evaluated heterogeneity and bias with subgroup, sensitivity, regression, and sequential analysis.

Results UDCA reduced the risk of ultrasound-verified gallstones compared with control interventions (risk ratio, 0.33; 95% confidence interval [CI], 0.18–0.60; number needed to treat, 9). This effect was significantly larger in trials of diets alone (risk ratio, 0.17; 95% CI, 0.11–0.25) than in trials of patients who underwent bariatric surgery (risk ratio, 0.42; 95% CI, 0.21–0.83) (test for subgroup differences, P =.03). UDCA reduced the risk of cholecystectomy for symptomatic stones (risk ratio, 0.20; 95% CI, 0.07–0.53). Diets high in fat content also reduced gallstones, compared with those with low fat content (risk ratio, 0.09; 95% CI, 0.01–0.61). The meta-analyses were confirmed in trials with a low risk of bias but not in sequential analysis. No additional beneficial or harmful outcomes were identified.