I found one of the early studies (2003) demonstrating the effectiveness and safety of an Atkins-style diet in the severely obese. Doctors traditionally have been hesitant to recommend the Atkins diet out of concern for tolerability and potential increased atherosclerosis complication such as heart attacks, strokes, and poor circulation.
The study enrolled 132 subjects with an average body mass index of 43, including 77 blacks and 23 women. 39% had diabetes, 43% had metabolic syndrome. They were randomly assigned to either . . .
- a low-carb diet without caloric restriction (carbohydrates limited to 30 gm/day; vegetables and fruits with high ratios of fiber to carbohydrate were recommended), or
- a low-fat, calorie-restricted diet.
Subjects followed their diets for six months. The researchers never specified, but I’m assuming the diabetics were all type 2.
The drop-out rate was equally high in both groups: only 79 subjects completed the study. The low-carb group lost 5.8 kg (13 lb); the low-fat group lost 1.9 kg (4 lb). Analysis included the drop-outs, for reasons unclear to me. White subjects lost more weight than blacks: 13 versus 5 kg (29 versus 11 lb). Total cholesterol, HDL cholesterol, and LDL cholesterol levels did not change significantly within or between groups. [HDL usually rises on a low-carb diet.] Triglycerides fell 20% in the low-carb group and 4% in the other group. For subjects with diabetes, glucose levels fell 26 mg/dl in the low-carb group compared to 5 mg/dl in the low-fat group. Uric acid levels didn’t change in either group. [Elevated uric acid levels can cause gout.] No significant adverse reactions attibutable to the diets were recorded in either group. Glycosylated hemoglobin fell from 7.8 to 7.2% in the low-carb group, with no change in the low-fat group.
It’s a small study, so results may not be very accurate or generalizable to other populations.
In this cohort with a high prevalence of diabetes, the low-carb diet was more effective than the low-fat/calorie-restricted diet for weight loss, with no adverse lipid changes to suggest increased long-term cardiovascular risk. The low-carb diet helped control diabetes.
Steve Parker, M.D.
Reference: Samaha, Frederick, et al. A low-carbohydrate as compared with a low-fat diet in severe obesity. New England Journal of Medicine, 348 (2003): 2,074-2,081.