Individuals who restrict themselves to very-low-calorie diets may be at increased risk of developing gallstones that require hospitalization or cholecystectomy, according to the results of a study published online on May 22, 2013, in the International Journal of Obesity
The study followed individuals enrolled in a commercial weight-loss program in 28 Swedish centers between 2006 and 2009. The year-long program restricted participants to either a very-low-calorie diet consisting of 500 calories a day or a low-calorie diet of 1200 to 1500 calories per day. After 3 months, participants gradually returned to normal caloric intake to maintain their weight loss over a 9-month period. Participants were matched with controls based on age, sex, body mass index, and gallstone history. Researchers collected data on participants’ gallstones and cholecystectomies from the Swedish National Patient Register.
After 1 year, participants in the very-low-calorie group lost an average of 24.5 pounds, compared with 18 pounds for those in the low-calorie group. However, 48 participants in the very-low-calorie group developed gallstones requiring hospitalization or cholecystectomy, compared with 16 participants in the low-calorie group. The researchers conclude that the risk of developing gallstones that required hospitalization or cholecystectomy was 3 times higher for those on a very-low-calorie diet compared with those on a low-calorie diet.