People shed more weight on an entirely plant based diet, even if carbohydrates are also included, a study has concluded. Other benefits of eating a vegan diet include decreased levels of saturated and unsaturated fat, lower BMIs, and improved macro nutrients.
The study, conducted by the university's Arnold School of Public Health and published in The International Journal of Applied and Basic Nutritional Sciences, compared the amount of weight lost by those on vegan diets to those on a mostly plant-based diet, and those eating an omnivorous diet with a mix of animal products and plant based foods. At the end of six months, individuals on the vegan diet lost more weight than the other two groups by an average of 4.3%, or 16.5 pounds.
The study followed participants who were randomly assigned to one of five diets on the dietary spectrum: vegan which excludes all animal products, semi-vegetarian with occasional meat intake; pesco-vegetarian which excludes all meat except seafood; vegetarian which excludes all meat and seafood but includes animal products, and omnivorous, which excludes no foods.
Participants followed their assigned dietary restrictions for six months, with all groups except the omnivorous participating in weekly group meetings. Those who stuck to the vegan diet showed the greatest weight loss at the two and six month marks.
The lead author on this study, Gabrielle Turner-McGrievy notes that the diet consumed by vegan participants was high in carbohydrates that rate low on the glycemic index. "We've gotten somewhat carb-phobic here in the U.S. when it comes to weight loss. This study might help alleviate the fears of people who enjoy pasta, rice, and other grains but want to lose weight," she said.
Weight loss was not the only positive outcome for participants in the strictly vegan group. They also showed the greatest amount of decrease in their fat and saturated fat levels at the two and six month checks, had lower BMIs, and improved macro nutrients more than other diets. Eschewing all animal products appears to be key for these positive results. "I personally was surprised that the pesco-vegetarian group didn't fare better with weight loss. In the end, their loss was no different than the semi-vegetarian or omnivorous groups," McGrievy said.
Turner-McGrievy is an assistant professor at the University of South Carolina in the Department of Health Promotion, Education, and Behavior. Some of her research focuses on plant-based dietary approaches for chronic disease prevention and treatment among adults.