High-fat, carbohydrate-restricted diets are a superior treatment option for type 2 diabetes compared to a low-calorie, low fat diet

This study was published in the New England Journal of Medicine 2003 May 22;348(21):2074-81

Study title and authors:

A low-carbohydrate as compared with a low-fat diet in severe obesity.

Samaha FF, Iqbal N, Seshadri P, Chicano KL, Daily DA, McGrory J, Williams T, Williams M, Gracely EJ, Stern L.

Philadelphia Veterans Affairs Medical Center, University of Pennsylvania Medical Center, Philadelphia, USA. rick.samaha@med.va.gov

This study can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/12761364

This study investigated the effects of a carbohydrate-restricted diet or a calorie- and fat-restricted diet on severely obese people. The trial lasted for six months and included 132 severely obese subjects with an average body-mass index of 43 and a high prevalence of diabetes (39 percent) or the metabolic syndrome (43 percent).

The subjects were assigned to either of two diets:
(i) The subjects assigned to the low-fat diet received instruction in accordance with the obesity-management guidelines of the National Heart, Lung, and Blood Institute, including caloric restriction sufficient to create a deficit of 500 calories per day, with 30 percent or less of total calories derived from fat. (Low fat diet).
(ii) The subjects assigned to the low-carbohydrate diet were instructed to restrict carbohydrate intake to 30 g per day or less. No instruction on restricting total fat intake was provided. (High fat diet).


The study found:
(a) Those on the high fat diet lost an extra 3.9 kg (8.6 lb) compared to those on the low fat diet.
(b) The high unhealthy triglyceride levels of those on the high fat diet decreased by an extra 31 mg/dL (.35 mmol/l) compared to those on the low fat diet.
(c) The high unhealthy Hb1AC levels decreased by .6% in those on the high fat diet, whereas Hb1AC levels remained the same in those on the low fat diet.
(d) The unhealthy high glucose levels of those on the high fat diet decreased by an extra 9 mg/dL (.5 mmol/l) compared to those on the low fat diet.
(e) There was a greater increase in insulin sensitivity in those on the high fat diet compared to those on the low fat diet.


The results of this study show how a high-fat, carbohydrate-restricted diet is a superior treatment option for type 2 diabetes compared to a low-calorie, low fat diet.