People who follow a very strict low-calorie diet are more likely to develop gallstones than those who follow a moderate diet . Dr. Michael Jensen, a professor of medicine at the Mayo Clinic, believes that dieters will eventually shed extra pounds, regardless of the degree of calorie restriction. “The end result will be the same, so why risk your health once again,” says Jensen. “The desire to lose weight quickly can lead you to the surgical table.”

Dr. Kari Johansson, lead author of the study and researcher at the Karolinska Institute in Sweden, suggested that rapid weight loss on very low-calorie diets has an effect on the salt and cholesterol content of bile and on gallbladder emptying, which causes gallstones. To see how diets affect the risk of gallstones in real-life settings, Johansson and her colleagues collected information from patients. Their study was based on data from 6,640 patients, half of whom were on a regular diet and the other half were on a low-calorie diet.

The strict diet menu consisted of liquid cereals of 500 kcal each, which the patients consumed for 10 weeks, and then gradually returned to their usual diet of normal food.

People in the other group consumed 1200-1500 calories per day for three months, including liquid first meals. After three months of a rigid diet, people lost about 30 pounds, and after three months of a regular diet, 17 pounds. After one year, among those who adhered to a strict diet, doctors recorded 48 cases of gallstones, and in the other group only 16. Doctors still find it difficult to explain the results. Perhaps the formation of stones is related to the amount of fat consumed. Scientists need a deeper study of this issue and so far they are convincingly asking people to abandon rigid low-calorie diets.