Replacing animal products with a plant-based diet leads to weight loss, finds new analysis

Replacing animal products with plant-based foods, whether these were so-called healthful or unhealthful plant-based foods according to the plant-based diet index, is associated with weight loss in overweight adults, reduced cholesterol and fat intake, and increased fiber intake, according to a new analysis by the Physicians Committee for Responsible Medicine published in the European Journal of Clinical Nutrition.

“While a low-fat vegan diet rich in fruits, vegetables, grains, and beans is the gold standard for weight loss and improved health, the good news is that a plant-based diet that eliminates animal products and minimizes the consumption of oil can help with weight loss in people who are overweight,” says study co-author Hana Kahleova, MD, PhD, director of clinical research at the Physicians Committee for Responsible Medicine.

The findings are from a secondary analysis of a Physicians Committee study in which 244 overweight adults were randomly assigned to a vegan group that followed a low-fat vegan diet or a control group that made no diet changes for 16 weeks. Calorie intake was not limited for either group, and neither group was given diet quality instructions.

The new analysis assessed the association of a plant-based diet index (PDI), healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI) with weight loss. The PDI measures adherence to a plant-based diet in general, the hPDI includes more fruits, vegetables, grains, and beans, and the uPDI includes more foods such as refined grains and fruit juices. The scores of all three indexes are higher with increased consumption of plant-based foods and reduced consumption of animal products.

In the analysis, all three scores increased for participants following a vegan diet, which was significantly associated with an average weight loss of about 13 pounds, due primarily to the reduction in fat mass and visceral fat. Increased consumption of whole grains and legumes and reduced consumption of meat, vegetable oil, and sweets in the vegan group was associated with weight loss. There was no change in scores in the control group.