Long-term weight patterns and risk for cholecystectomy in women.

BACKGROUND: Obesity and rapid weight loss in obese persons are known risk factors for gallstones. However, the effect of intentional, long-term, moderate weight changes on the risk for gallstones is unclear.

OBJECTIVE: To study long-term weight patterns in a cohort of women and to examine the relation between weight pattern and risk for cholecystectomy.

DESIGN: Prospective cohort study.

SETTING: 11 U.S. states.

PARTICIPANTS: 47,153 female registered nurses who did not undergo cholecystectomy before 1988.

MEASUREMENTS: Cholecystectomy between 1988 and 1994 (ascertained by patient self-report).

RESULTS: During the exposure period (1972 to 1988), there was evidence of substantial variation in weight due to intentional weight loss during adulthood. Among cohort patients, 54.9% reported weight cycling with at least one episode of intentional weight loss associated with regain. Of the total cohort, 20.1% were light cyclers (5 to 9 lb of weight loss and gain), 18.8% were moderate cyclers (10 to 19 lb of weight loss and gain), and 16.0% were severe cyclers (> or = 20 lb of weight loss and gain). Net weight gain without cycling occurred in 29.3% of women; net weight loss without cycling was the least common pattern (4.6%). Only 11.1% of the cohort maintained weight within 5 lb over the 16-year period. In the study, 1751 women had undergone cholecystectomy between 1988 and 1994. Compared with weight maintainers, the relative risk for cholecystectomy (adjusted for body mass index, age, alcohol intake, fat intake, and smoking) was 1.20 (95% CI, 0.96 to 1.50) among light cyclers, 1.31 among moderate cyclers (CI, 1.05 to 1.64), and 1.68 among severe cyclers (CI, 1.34 to 2.10).

CONCLUSION: Weight cycling was highly prevalent in this large cohort of middle-aged women. The risk for cholecystectomy associated with weight cycling was substantial, independent of attained relative body weight.