Science

Lydia A. Bazzano, MD, PhD, MPH; Tian Hu, MD, MS; Kristi Reynolds, PhD; Lu Yao, MD, MS; Calynn Bunol, MS, RD, LDN; Yanxi Liu, MS; Chung-Shiuan Chen, MS; Michael J. Klag, MD, MPH; Paul K. Whelton, MD, MSc, MB; and Jiang He, MD, PhD

Background:
Low-carbohydrate diets are popular for weight loss, but their cardiovascular effects have not been well-studied, particularly in diverse populations.
Objective:
To examine the effects of a low-carbohydrate diet compared with a low-fat diet on body weight and cardiovascular risk factors.
Design:
A randomized, parallel-group trial. (ClinicalTrials.gov: NCT00609271)
Setting:
A large academic medical center.
Participants:
148 men and women without clinical cardiovascular disease and diabetes.
Intervention:
A low-carbohydrate (less than 40 g/d) or low-fat (less than 30% of daily energy intake from total fat [less than 7% saturated fat]) diet. Both groups received dietary counseling at regular intervals throughout the trial.
Measurements:
Data on weight, cardiovascular risk factors, and dietary composition were collected at 0, 3, 6, and 12 months.
Results:
Sixty participants (82%) in the low-fat group and 59 (79%) in the low-carbohydrate group completed the intervention. At 12 months, participants on the low-carbohydrate diet had greater decreases in weight (mean difference in change, −3.5 kg [95% CI, −5.6 to −1.4 kg]; P = 0.002), fat mass (mean difference in change, −1.5% [CI, −2.6% to −0.4%]; P = 0.011), ratio of total–high-density lipoprotein (HDL) cholesterol (mean difference in change, −0.44 [CI, −0.71 to −0.16]; P = 0.002), and triglyceride level (mean difference in change, −0.16 mmol/L [−14.1 mg/dL] [CI, −0.31 to −0.01 mmol/L {−27.4 to −0.8 mg/dL}]; P = 0.038) and greater increases in HDL cholesterol level (mean difference in change, 0.18 mmol/L [7.0 mg/dL] [CI, 0.08 to 0.28 mmol/L {3.0 to 11.0 mg/dL}]; P less than 0.001) than those on the low-fat diet.
Limitation:
Lack of clinical cardiovascular disease end points.
Conclusion:
The low-carbohydrate diet was more effective for weight loss and cardiovascular risk factor reduction than the low-fat diet. Restricting carbohydrate may be an option for persons seeking to lose weight and reduce cardiovascular risk factors.
Primary Funding Source:
National Institutes of Health.