A low-carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia: a randomized, controlled trial
William S Yancy Jr 1, Maren K Olsen, John R Guyton, Ronna P Bakst, Eric C Westman
To compare the effects of a low-carbohydrate, ketogenic diet program with those of a low-fat, low-cholesterol, reduced-calorie diet. 120 overweight, hyperlipidemic volunteers were given either:
1. Low-carbohydrate diets (initially, <20 g of carbohydrate daily) plus nutritional supplementation, exercise recommendations, and group meetings.
2. Low-fat diet (<30% energy from fat, <300 mg of cholesterol daily, and deficit of 500 to 1000 kcal/d) plus exercise recommendation and group meetings.
Limitations: We could not definitively distinguish effects of the low-carbohydrate diet and those of the nutritional supplements provided only to that group. In addition, participants were healthy and were followed for only 24 weeks. These factors limit the generalizability of the study results.
A greater proportion of the low-carbohydrate diet group than the low-fat diet group completed the study (76% vs. 57%; P = 0.02).
At 24 weeks, weight loss was greater in the low-carbohydrate diet group than in the low-fat diet group (mean change, -12.9% vs. -6.7%; P < 0.001).
Both groups lost substantially more fat mass (change, -9.4 kg with the low-carbohydrate diet vs. -4.8 kg with the low-fat diet) than fat-free mass (change, -3.3 kg vs. -2.4 kg, respectively).
Compared with recipients of the low-fat diet, recipients of the low-carbohydrate diet had greater decreases in serum triglyceride levels (change, -0.84 mmol/L vs. -0.31 mmol/L [-74.2 mg/dL vs. -27.9 mg/dL]; P = 0.004) and greater increases in high-density lipoprotein cholesterol levels (0.14 mmol/L vs. -0.04 mmol/L [5.5 mg/dL vs. -1.6 mg/dL]; P < 0.001).
Changes in low-density lipoprotein cholesterol level did not differ statistically (0.04 mmol/L [1.6 mg/dL] with the low-carbohydrate diet and -0.19 mmol/L [-7.4 mg/dL] with the low-fat diet; P = 0.2).
Minor adverse effects were more frequent in the low-carbohydrate diet group.
IN PLAIN ENGLISH:
Compared with a low-fat diet, a low-carbohydrate diet program had better participant retention and greater weight loss.
During active weight loss, serum triglyceride levels decreased more, and high-density lipoprotein cholesterol level increased more with the low-carbohydrate diet than with the low-fat diet.