Very-low-calorie diet tied to greater gallstone risk
PEOPLE who go on an extremely-low-calorie diet are more likely to develop gallstones than people on a moderately-low-calorie diet, according to a new study.
Dr Michael Jensen, a professor of medicine at the Mayo Clinic, said that dieters typically end up with similar weight loss in the long run whether they exercise extreme calorie restriction or go on more moderately restricted diets.
"You're going to end up in the same place (weight-wise), so why take the risk of ending up in a hospital with a gall-bladder problem just to lose weight faster?" said Dr Jensen, who was not part of the study.
Dr Kari Johansson, the lead author of the study and a researcher at the Karolinska Institute in Sweden, said quick weight loss from very-low-calorie diets is thought to impact the salt and cholesterol contents of bile and the emptying of the gall bladder, both of which can contribute to gallstones.
To see how these diets affect gallstone risk in a real-world setting, Dr Johansson and her colleagues collected information on customers' progress from a weight-loss company in Sweden, called Intrim.
Some of the study authors have worked for the company or serve on its scientific advisory board.
Their study included 6,640 dieters, half of whom went on a crash diet and the other half of whom went on a low-calorie diet.
The crash diet involved liquid meals of just 500 calories a day for six to 10 weeks, followed by the gradual introduction of normal food, and then nine months of a weight-maintenance regime of exercise and healthy eating.
The other dieters ate 1,200 to 1,500 calories a day, including two liquid meals, for three months, followed by the nine-month weight-maintenance period.
After three months in the weight-loss programme, the crash dieters lost about 13kg, compared to roughly 7kg lost among people on the low-calorie diet.
One year from the start of the diet, the extremely-low-calorie group had lost an average of 11kg, while the other group lost about 8kg.
Among those on the crash diet, 48 people developed gallstones requiring hospital treatment, and 16 people in the other group developed gallstones, Dr Johansson and her colleagues reported in the International Journal Of Obesity.
They could not determine why gallstones were more common among people in the extremely-low-calorie group.