Return of the Low-Fat Diet

Healthnotes Newswire (December 1, 2005)—Adhering to a low-fat, strict vegetarian (vegan) diet may lead to significant weight loss in overweight postmenopausal women, reports the American Journal of Medicine (2005;118:991–7).

Obesity and overweight are associated with higher rates of heart disease, type 2 diabetes, high blood pressure, stroke, gallbladder disease, and certain cancers. Vegetarian diets may lower the risk of developing many of these conditions.

Vegetarians may choose to incorporate dairy products, eggs, or both in their diets. The vegan diet is vegetarianism in its purest form, excluding all animal products, including honey. In the early 1990s, Dean Ornish, MD, popularized an extremely low-fat, (nearly) vegan diet with his book, Dr. Dean Ornish’s Program for Reversing Heart Disease. Despite its numerous health benefits, however, the vegan diet may be deficient in some key nutrients, including vitamin B12, calcium, iron, vitamin D, and essential fatty acids such as those found in fish.

The new study aimed to determine the effects of a low-fat vegan diet on weight loss and blood-sugar control in 59 post-menopausal women who were overweight. The women were instructed to follow either a low-fat vegan diet or a control diet that was based on the National Cholesterol Education Program guidelines for 14 weeks. The vegan diet derived 10% of total calories from fat, 15% from protein, and 75% from carbohydrates. No added oils, avocados, olives, nuts, nut butters, or seeds were permitted on the diet. The control diet derived 30% or less of total calories from fat (no more than 7% from saturated fat), 15% from protein, and 55% from carbohydrates. Portion sizes and caloric intake were not restricted with either diet.

At the beginning and end of the study, body weight, hip and waist circumferences, body mass index (BMI), level of physical activity, and markers of blood-sugar metabolism were measured. Women who adhered to the vegan diet lost over 13 pounds during the study period, significantly more than the women in the control group. Women in the vegan group also ate significantly less protein, fat, and cholesterol and more fiber and carbohydrates than did the control group. BMI and waist-circumference measurements decreased significantly in the vegan group compared with the control group, suggesting a greater decrease in body fat in the vegan diet group. Compared with baseline measurements, women who followed the vegan diet had significantly improved measures of blood-sugar control.

Previous studies have pointed out that dietary adherence, not type of diet, predicts the amount of weight loss. For this reason, consuming a low-fat vegan diet without caloric restriction may appeal to some people who dislike calorie counting but who are able to stick to other dietary restrictions. Supplementing with a high-quality multivitamin-mineral formula should supply adequate amounts of vitamin B12 and most other nutrients that may be low in a vegan diet.

Kimberly Beauchamp, ND, earned her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She cofounded South County Naturopaths in Wakefield, RI. Dr. Beauchamp practices as a birth doula and lectures on topics including whole-foods nutrition, detoxification, and women’s health.

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