The effects of low-carbohydrate versus conventional weight loss diets in severely obese adults: one-year follow-up of a randomized trial.

Ann Intern Med. 2004 May 18;140(10):778-85.

The effects of low-carbohydrate versus conventional weight loss diets in severely obese adults: one-year follow-up of a randomized trial.
Stern L, Iqbal N, Seshadri P, Chicano KL, Daily DA, McGrory J, Williams M, Gracely EJ, Samaha FF.

Philadelphia Veterans Affairs Medical Center, University of Pennsylvania Medical Center, and Drexel University College of Medicine, Philadelphia, Pennsylvania 19104, USA.

Comment in:

Ann Intern Med. 2004 May 18;140(10):I27.
Ann Intern Med. 2004 Nov 2;141(9):738; author reply 738-9.
Ann Intern Med. 2004 May 18;140(10):836-7.

Abstract
BACKGROUND: A previous paper reported the 6-month comparison of weight loss and metabolic changes in obese adults randomly assigned to either a low-carbohydrate diet or a conventional weight loss diet.

OBJECTIVE: To review the 1-year outcomes between these diets.

DESIGN: Randomized trial.

SETTING: Philadelphia Veterans Affairs Medical Center.

PARTICIPANTS: 132 obese adults with a body mass index of 35 kg/m2 or greater; 83% had diabetes or the metabolic syndrome.

INTERVENTION: Participants received counseling to either restrict carbohydrate intake to <30 g per day (low-carbohydrate diet) or to restrict caloric intake by 500 calories per day with <30% of calories from fat (conventional diet).

MEASUREMENTS: Changes in weight, lipid levels, glycemic control, and insulin sensitivity.

RESULTS: By 1 year, mean (+/-SD) weight change for persons on the low-carbohydrate diet was -5.1 +/- 8.7 kg compared with -3.1 +/- 8.4 kg for persons on the conventional diet. Differences between groups were not significant (-1.9 kg [95% CI, -4.9 to 1.0 kg]; P = 0.20). For persons on the low-carbohydrate diet, triglyceride levels decreased more (P = 0.044) and high-density lipoprotein cholesterol levels decreased less (P = 0.025). As seen in the small group of persons with diabetes (n = 54) and after adjustment for covariates, hemoglobin A1c levels improved more for persons on the low-carbohydrate diet. These more favorable metabolic responses to a low-carbohydrate diet remained significant after adjustment for weight loss differences. Changes in other lipids or insulin sensitivity did not differ between groups.

LIMITATIONS: These findings are limited by a high dropout rate (34%) and by suboptimal dietary adherence of the enrolled persons.

CONCLUSION: Participants on a low-carbohydrate diet had more favorable overall outcomes at 1 year than did those on a conventional diet. Weight loss was similar between groups, but effects on atherogenic dyslipidemia and glycemic control were still more favorable with a low-carbohydrate diet after adjustment for differences in weight loss.