The role of gallbladder emptying in gallstone formation during diet-induced rapid weight loss.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 8781321 · doi:10.1002/hep.510240313
What was done
Obese individuals were randomized to one of two liquid rapid-weight-loss diets: a 520-kcal/day diet containing less than 2 g fat/day, or a 900-kcal/day diet containing 30 g fat/day (including one 10-g fat meal to stimulate maximal gallbladder emptying). Investigators repeatedly measured weight loss, ultrasonographic gallbladder emptying, bile and blood lipids, cholesterol saturation index, and leukocyte HMG CoA reductase activity.
What was found
Both diets produced a 22% weight loss. Bile cholesterol saturation index increased by 26% during both diets and fell to 15% below baseline after weight loss. Compared to subjects' maximal baseline gallbladder emptying fraction of 66%, the 520-kcal diet produced poor emptying (35%), whereas the 10-g fat meal in the 900-kcal diet provided maximal emptying. Gallstones developed in 4 of 6 subjects on the 520-kcal diet and 0 of 7 subjects on the 900-kcal diet (P = .021), prompting early study termination for ethical reasons.
Why it matters
This study shows that gallbladder stasis from lack of dietary fat—not just cholesterol supersaturation—drives gallstone formation during rapid weight loss. Incorporating a small amount of dietary fat (~10 g) to stimulate regular gallbladder emptying can prevent stone formation.
Limits
The total sample size was very small (13 subjects) due to premature termination. Long-term outcomes and generalization to non-liquid diets or slower weight-loss rates were not evaluated.
Cited by
- supports Dietary fat intake stimulates the release of bile from the gallbladder.