Vegan diets are better for weight loss and controlling cholesterol levels compared to the Mediterranean diet, which popular belief has often hailed as a guide to losing weight, a new study has shown. Putting the two diets head-to-head in a randomised crossover trial, the researchers also found that low-fat plant-based diets resulted in more positive outcomes in terms of insulin sensitivity and body composition.
The study, published in the peer-reviewed Journal of the American College of Nutrition, compared the Mediterranean diet against a low-fat vegan diet, and found that the latter was more effective for weight loss, body composition, insulin sensitivity, as well as cholesterol levels. Researchers conducted a randomised crossover trial, where half of the cohort of overweight participants with no history of diabetes were prescribed either one of the diets for 16 weeks, before switching to the other diet for 16 weeks after a four-week “washout” period.
While the Mediterranean diet consisted of fruits, vegetables, legumes, fish, low-fat dairy, and extra virgin olive oil, limiting red meat and saturated fats as per PREDIMED guidelines, the low-fat vegan diet eliminated all animal-based products and contained fruits, vegetables, whole grains and legumes. Participants in the study were not given a calorie limit, and no other factors were changed, such as exercise regimen and medication routines.
It represents one of the first scientific trials that compares the two diets side-by-side. “Previous studies have suggested that both Mediterranean and vegan diets improve body weight and cardiometabolic risk factors, but until now, their relative efficacy had not been compared in a randomised trial,” explained Dr. Hana Kahleova, co-author of the study and director of clinical research at the Physicians Committee.
We decided to test the diets head to head and found that a vegan diet is more effective for both improving health markers and boosting weight loss.Dr. Hana Kahleova
The specific findings of the study suggests that low-fat vegan diets were more successful on multiple health indices, but most of all, in terms of weight loss and fat loss. Within the 16-week period, participants lost an average of 6 kilograms on the vegan diet, compared to no change on the Mediterranean diet. When it came to fat, low-fat vegan diets resulted in 3.4 kilograms more fat mass lost and a greater reduction in visceral fat by 315 centimetres squared.
Researchers further found that the plant-based diet decreased the total and LDL cholesterol levels of participants by 18.7 mg/dL and 15.3 mg/dL respectively, while the Mediterranean diet showed no significant change.
The only factor that saw the Mediterranean diet perform better than the vegan diet was on blood pressure, where levels decreased by 6.0 mm Hg compared to 3.2 mmHg.
Commenting on the findings, Dr. Kahleova said: “We decided to test the diets head to head and found that a vegan diet is more effective for both improving health markers and boosting weight loss.”
The authors of the paper attribute the efficacy of the vegan diet for weight loss because it was associated with a greater reduction in calorie intake, higher fibre consumption, lower intake of fats, especially saturated fats.
“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,” said co-author of the study and president of the Physicians Committee Dr. Neal Barnard, who added that the “problem” with the Mediterranean diet seemed to be the consumption of dairy products, fatty fish and oils.
Researchers hope that the results will encourage more people who have set their New Year’s goals to live a healthier lifestyle or to lose excess weight to choose a plant-based diet, which they describe a “great way to achieve your resolution”.
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.Dr. Neal Barnard
A number of other scientific papers have also found positive health outcomes associated with plant-based diet, with one recent large-scale study concluding a correlation between plant-based diets and gut microbes that help lower risks for heart disease, obesity and diabetes.
Another study, led by the National Cancer Institute in the U.S., found an “inverse association” between higher consumption of plant-based foods and heart disease mortality rates. The most prominent inverse associations were recorded in the replacement of eggs and red meat with plant proteins.
In addition to supporting human health, plant-based proteins are also more environmentally-friendly. An Oxford University 2019 study found that healthy plant-based foods are almost always associated with a smaller carbon footprint.
Lead image courtesy of Getty Images.