Low-fat, high-carbohydrate (low-glycaemic index) diet induces weight loss and preserves lean body mass in obese healthy subjects: results of a 24-week study.

Background:  The traditional treatment for obesity which is based on a reduced caloric diet has only been partially successful. Contributing factors are not only a poor long-term dietary adherence but also a significant loss of lean body mass and subsequent reduction in energy expenditure. Both low-fat, high-carbohydrate diets and diets using low-glycaemic index (GI) foods are capable of inducing modest weight loss without specific caloric restriction. The purpose of this study was to investigate the feasibility and medium-term effect of a low-fat diet with high (low GI) carbohydrates on weight loss, body composition changes and dietary compliance. Methods:  Obese patients were recruited from two obesity outpatient clinics. Subjects were given advise by a dietician, then they attended biweekly for 1-hour group meetings. Bodyweight and body composition were measured at baseline and after 24 weeks. Results:  One hundred and nine (91%) patients completed the study; after 24 weeks the average weight loss was 8.9 kg (98.6 vs. 89.7 kg; p ≤ 0.0001). There was a significant 15% decrease in fat mass (42.5 vs. 36.4 kg; p ≤ 0.0001) and a decrease in lean body mass of 5% (56.1 vs. 53.3 kg; p ≤ 0.0001). Discussion:  In this 6-month study, a low-fat, low-GI diet led to a significant reduction of fat mass; adherence to the diet was very good. Our results suggest that such a diet is feasible and should be evaluated in randomized controlled trials.