Low-Fat, Vegan Diet May Be Effective for Weight Loss

Laurie Barclay, MD

September 15, 2005

Sept. 15, 2005 -- An ad libitum low-fat, vegan diet is effective for weight loss, according to the results of a 14-week trial reported in the September issue of the American Journal of Medicine.

"Prior studies have suggested that low-fat, plant-based diets reduce body weight, improve cardiovascular risk factors and glycemic control, and, in combination with other lifestyle interventions, reverse atherosclerosis," write Neal D. Barnard, MD, from George Washington University School of Medicine in Washington, D.C., and colleagues. "However, few studies have examined the effect of such diets on body weight or insulin sensitivity in overweight individuals while controlling for the confounding effects of exercise."

In this study, 64 overweight, postmenopausal women outpatients were randomized to a low-fat, vegan diet or a control diet based on National Cholesterol Education Program guidelines, without energy intake limits. The participants were asked not to change their typical level of exercise. Dietary intake, body weight and composition, resting metabolic rate, thermic effect of food, and insulin sensitivity were recorded at baseline and at 14 weeks.

Mean body weight decreased by 5.8 ± 3.2 kg in the vegan group and by 3.8 ± 2.8 kg in the control group ( P = .012). Based on a regression model, significant predictors of weight change were diet group ( P < .05), thermic effect of food ( P < .05), and resting metabolic rate ( P < .001). Although an index of insulin sensitivity increased from 4.6 ± 2.9 to 5.7 ± 3.9 ( P = .017) in the vegan group, the difference between groups was not significant ( P = .17).

"In a controlled trial, the consumption of a low-fat, vegan diet was associated with significant weight reduction, along with improvements in measures of glucose tolerance and insulin sensitivity," the authors write.

Study limitations include failure to address diet sustainability over the longer term; dietary reporting limited to three days at each data point; and possible underreporting of food intake.

"The effect of a vegan diet on the thermic effect of food merits further exploration," the authors conclude. "Longer-term trials will define the sustainability of the intervention diet and resultant clinical improvements."

The Cancer Project, Washington, D.C., funded this study.

Am J Med. 2005;118:991-997

Reviewed by Gary D. Vogin, MD


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