(BMI) of 18.5–24.9 is considered normal weight and a
BMI of 25.0–29.9 is overweight. A BMI of 30 and
above is obese. A woman with a BMI of 32 has about
a three times greater risk of developing gallstones than
a woman with a BMI of 25.
too much cholesterol. If the liver makes too much
cholesterol, it may not stay dissolved in bile, but may
crystallize out and form a solid. The amount of cho-
lesterol in bile is not related to the amount of choles-
terol in blood, and lowering-lowering drugs do not
affect the amount of cholesterol the liver makes.
female gender, pregnancy, and estrogen drugs. The
female hormone estrogen causes the liver to make
more cholesterol. Women of reproductive age have
higher levels of estrogen, which may explain why
more women develop gallstones than men. In addi-
tion oral contraceptives (birth control pills) contain
estrogen, and until recently, many women took drugscontaining estrogen to combat hot flashes and other
symptoms of menopause. Gallstone formation also
increases during pregnancy, a time of increased
estrogen levels.
severe dieting. Losing weight rapidly—3 or more
pounds a week— increases the likelihood of developing
gallstones. About one-quarter of people who go on
very low calorie diets (800 calories daily under medical
supervision) and stay on them for several months
develop gallstones. One-third of these people have
symptoms severe enough toneed gallbladder surgery.
About one-third of people who have weight-loss sur-
gery (bariatric surgery) also develop gallstones, usually
in the first few months after surgery. Experts believe
that somehow that triggers gallstone formation.
The chance of developing pigment gallstones is
increased in individuals who have diseases such as
sickle-cell anemia where there is an unusually highGallstones in the gallbladder and the common bile duct.(Illustration by Electronic Illustrators Group/Thomson Gale.)Gallstones