Both Mediterranean and vegan diets are known to have significant weight loss efficacy, but when compared head-to-head, vegan diets are more effective for weight loss, cholesterol control, body composition, and insulin sensitivity.
Overweight management has remained one of the top health agenda in the last two decades as a growing number of people are either overweight or obese. The conditions are highly correlated with comorbidities like hypertension, cardiovascular disease, and diabetes.
To address the issue, plenty of research has been done linking dietary interventions with over-weight management and weight loss. Though in many instances, the outcomes are the other way around—diet restrictions may help some people achieve their weight-loss goals but don’t bring the same results to others—still dietary intervention is the most common weight-control strategy recommended by health practitioners.
A group of PCRM (Physicians Committee for Responsible Medicine) scientists based in Washington DC, in a recent clinical trial, evaluated the weight loss efficacy of a vegan diet and compared it with the Mediterranean diet.
The randomized crossover trial is published in the Journal of the American College of Nutrition, showing that a low-fat vegan diet has better outcomes for weight, body composition, insulin sensitivity, and cholesterol levels compared with a Mediterranean diet (Barnard, Alwarith et al. 2021).
According to the authors, a “Mediterranean diet” includes abundant plant-based foods, favors olive oil as the primary source of fat, and includes low to moderate amounts of meat, dairy products, eggs, and wine; on the other hand, a vegan diet is rich in vegetables free of animal products: meat, milk, eggs, dairy products, and so on.
Both Mediterranean and vegan diets are known to have significant weight loss efficacy(Tonstad, Butler et al. 2009, Mancini, Filion et al. 2016). However, a head-to-head comparison study is rarely done. No such studies have been conducted that examined and compared relative effects of the Mediterranean and low-fat vegan diet for improving body weight or altering cardiovascular risk factors—the authors of the study stated.
The “study directly compared a Mediterranean and a vegan diet for their effects on weight and cardiometabolic parameters, using a crossover design.”
The study recruited adults with a body mass index between 28 and 40 kg/m2 between February and October 2019 in Washington, DC, and assigned them in two groups in a 1:1 ratio. One group was given a Mediterranean diet, while the other group started with a low-fat vegan diet. After 16 weeks, both groups returned to their baseline diet for a four-week washout before switching the diet for an additional 16 weeks.
Neither group had a calorie limit, neither the participants change their exercise or medication routines unless suggested by their personal care doctors.
The study found vegan treatment reduced 6 kg body weight compared with no change by the Mediterranean diet treatment. Participants on a vegan diet lost 3.4 kg more fat mass than the participants on the Mediterranean diet.
Similarly, vegan treatment reduced visceral fat by 315 cm3, total cholesterol by 18.7 mg/dL, LDL cholesterol levels by 15.3 mg/dL, respectively, with no significant changes on the Mediterranean diet. Participants on both diets had reduced blood pressure but 6.0 mm Hg on the Mediterranean diet compared to 3.2 mmHg on the vegan diet.
“While many people think of the Mediterranean diet as one of the best ways to lose weight, the diet actually crashed and burned when we put it to the test,” says study author Neal Barnard, MD, president of the Physicians Committee.
“In a randomized, controlled trial, the Mediterranean diet caused no weight loss at all. The problem seems to be the inclusion of fatty fish, dairy products, and oils. In contrast, a low-fat vegan diet caused significant and consistent weight loss”(Anderson 2021).
“If your goal is to lose weight or get healthy in 2021, choosing a plant-based diet is a great way to achieve your resolution,” adds Dr. Kahleova.