A diet free of animal products and low in fat may help trim the waistline without the task of strict calorie watching, a new study suggests.
Researchers found that of 64 postmenopausal, overweight women, those assigned to follow a low-fat vegan diet for 14 weeks lost an average of 13 pounds, compared with a weight loss of about 8 pounds among women who followed a standard low-cholesterol diet.
The weight loss came despite the fact that the women were given no limits on their portion sizes or daily calories - and despite the fact that the vegan diet boosted their carbohydrate intake.
"People imagine carbohydrates to be fattening, but they are not," said lead study author Dr Neal D. Barnard, an adjunct associate professor of medicine at George Washington University in Washington, D.C.
He is also president of Physicians Committee for Responsible Medicine, a non-profit group that advocates vegetarianism as part of preventive medicine.
The greater weight loss among women on the vegan diet may stem from specific metabolic effects, Barnard told Reuters Health.
He pointed out that the diet improved the women's sensitivity to insulin, a hormone that ushers sugar from the blood and into cells to be used for energy. This was also accompanied by an increase in what's known as the thermic effect of food - the amount of calories the body expends to process and store food.
The vegan diet improved women's insulin sensitivity to a greater a degree than the comparison diet did - though the difference was not statistically significant, meaning the finding could be due to chance.
Vegan diets eschew all animal products, including dairy and eggs, in favour of fruits and vegetables, grains, nuts and beans. Although high-protein weight-loss regimens have painted carbohydrates as the enemy, a number of studies have found that vegetarians and vegans, who tend to eat a lot of fiber- and vitamin-rich carbohydrates, are much less likely to be overweight than meat-eaters.