Gallbladder kinetics in obese patients. Effect of a regular meal and low-calorie meal.

Gallbladder contractility has been studied in 21 obese patients (greater than 130% ideal weight) and 30 nonobese subjects before and at regular intervals after the administration of a regular solid-liquid meal, and after a low-calorie, low-fat meal used conventionally for weight-loss purposes (Modifast). Gallbladder volume was determined by means of real-time ultrasonography, using a linear array scanner with a 3.5 MHZ probe. In seven of the obese patients, gallbladder contractility was also evaluated after a 10-day regimen with Modifast. The obese group showed a statistically significant greater gallbladder fasting volume and blunted contractility than controls both after the ordinary and the low-calorie meal. The 10-day low-calorie regimen was associated with a statistically significant increment in fasting gallbladder volume, while the percent volume reduction after Modifast did not change. It is suggested that, in addition to metabolic factors, gallbladder hypocontractility in the obese may contribute to the high incidence of cholesterol gallstones noted in these patients. A low-calorie, low-fat diet augmenting gallbladder volume may favor bile stasis and therefore the likelihood of developing gallstones.