According to a groundbreaking new study that compared diets head to head, a vegan diet is more effective than a Mediterranean diet for weight loss. The randomized crossover study that was published in the Journal of the American College of Nutritionfound that a low-fat vegan diet compared to a Mediterranean diet had better results in terms of weight, body composition, insulin sensitivity and cholesterol levels.

The study randomly assigned participants – who were overweight and had no history of diabetes – to a 1: 1 vegan or Mediterranean diet. For 16 weeks, half of the participants started a low-fat vegan diet that eliminated animal products and focused on fruits, vegetables, whole grains and legumes. The other half started on the Mediterranean Diet, which followed the PREDIMED protocol, which focused on fruits, vegetables, legumes, fish, low-fat dairy products, and extra virgin olive oil while limiting or avoiding red meat and saturated fats. Neither group had a calorie limit, and participants did not change their exercise or medication routine unless directed by their personal doctors. As part of the crossover design, participants returned to their basic diets for a four-week washout period before switching to the counter group for another 16 weeks.

The study found that within 16 weeks of each diet:

  • Participants lost an average of 6 kilograms (or about 13 pounds) on the vegan diet, compared to no mean change on the Mediterranean diet.
  • The participants lost 3.4 kg more fat mass through the vegan diet.
  • The participants saw a greater reduction in visceral fat by 315 cm3 with a vegan diet.
  • The vegan diet lowered total and LDL cholesterol levels by 18.7 mg / dl and 15.3 mg / dl, respectively, while the Mediterranean diet showed no significant changes in cholesterol.
  • Blood pressure decreased with both diets, but more so with the Mediterranean diet (6.0 mm Hg compared to 3.2 mm Hg with the vegan diet).

“Previous studies have shown that both Mediterranean and vegan diets improve body weight and cardiometabolic risk factors. However, their relative effectiveness has not yet been compared in a randomized trial,” says study author Hana Kahleova, MD, PhD, director of clinical research for the medical commission. “We decided to test the diets directly and found that a vegan diet is more effective at both improving health traits and increasing weight loss.”

The authors note that the vegan diet likely resulted in weight loss as it was associated with a decrease in caloric intake, an increase in fiber intake, a decrease in fat consumption, and a decrease in saturated fat consumption.

“While many people consider the Mediterranean Diet to be one of the best ways to lose weight, the diet actually crashed and burned when we put it to the test,” said study author Neal Barnard, MD, president of the Medical Committee. “In a randomized, controlled study, the Mediterranean diet caused no weight loss at all. The problem appears to be the inclusion of fatty fish, dairy products, and oils. In contrast, a low-fat vegan diet caused significant and consistent weight loss.”

“If you want to lose weight or get healthy in 2021, choosing a plant-based diet is a great way to achieve your solution,” adds Dr. Kahleova added.


For a copy of the study or an interview with a study author, please contact Laura Anderson at [email protected] or 202-527-7396.

Founded in 1985, the Physicians Committee for Responsible Medicine is a not-for-profit organization that promotes preventive medicine, conducts clinical research, and promotes higher standards of ethics and effectiveness in education and research.

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