Details: 132 individuals with severe obesity (mean BMI of 43) were randomized to either a low-fat or a low-carb diet. Many of the subjects had metabolic syndrome or type II diabetes. The low-fat dieters were calorie restricted. Study duration was 6 months.
Weight Loss: The low-carb group lost an average of 5.8 kg (12.8 lbs) while the low-fat group lost only 1.9 kg (4.2 lbs). The difference was statistically significant.
Conclusion: The low-carb group lost significantly more weight (about 3 times as much). There was also a statistically significant difference in several biomarkers:
- Triglycerides went down by 38 mg/dL in the LC group, compared to 7 mg/dL in the LF group.
- Insulin sensitivity improved on LC, got slightly worse on LF.
- Fasting blood glucose levels went down by 26 mg/dL in the LC group, only 5 mg/dL in the LF group.
- Insulin levels went down by 27% in the LC group, but increased slightly in the LF group.
Overall, the low-carb diet had significantly more beneficial effects on weight and key biomarkers in this group of severely obese individuals.
Samaha FF, et al. A low-carbohydrate as compared with a low-fat diet in severe obesity. New England Journal of Medicine, 2003.