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Research News: A groundbreaking new study has compared the vegan diet to the Mediterranean diet to ascertain which is best for weight-loss.  And which one crashed and burned. This is what the researchers found.

Weight loss is a global ideal

The world is grappling with an epidemic of weight gain and obesity.  Indeed, excess body weight and cardiovascular disease are major worldwide health problems. Approximately 70% of US adults are overweight. Nearly half have cardiovascular disease (including coronary heart disease, heart failure, stroke, or hypertension).

weight loss

But which diet?

There are many diet options available to those who need to lose weight. More often than not, dieters will lose weight, but with time and relaxation of sticking to a prescribed and often restrictive diet, the weight piles back on.  Many reports over many years have suggested that following a Mediterranean diet is the healthiest way to eat. It’s also a way of eating that is more sustainable and leads to greater longevity.

More recently, though, scientists have been suggesting that a plant-based diet, low in fat, is the best diet to follow for weight-loss.

Low-fat vegan diet and weight loss

First, in case you are wondering, the Mediterranean and vegan diets have long been studied for their effects on body weight and cardio-metabolic risk. A “Mediterranean diet” can refer to a variety of culinary traditions. The term has been codified for research purposes to refer to a diet that includes abundant plant-based foods. It also favors olive oil as the primary source of fat and includes low to moderate amounts of meat, dairy products, eggs, and wine.

This new study published in the Journal of the American College of Nutrition,  has specifically reviewed the two diets head to head. It has been reported that a low-fat vegan diet has better outcomes for weight, body composition, insulin sensitivity, and cholesterol levels, compared with a Mediterranean diet.

Let’s take a look at the findings in more detail.

What the study looked at

The study randomly assigned participants–who were overweight and had no history of diabetes–to a vegan diet or a Mediterranean diet in a 1:1 ratio.


For 16 weeks, half of the participants started with a low-fat vegan diet that eliminated animal products and focused on fruits, vegetables, whole grains, and legumes. The other half started with the Mediterranean diet, which followed the PREDIMED protocol, which focuses on fruits, vegetables, legumes, fish, low-fat dairy, and extra virgin olive oil while limiting or avoiding red meat and saturated fats.

extra virgin olive oil | Longevity LiveNo calorie limit

Neither group had a calorie limit. Also, participants did not change their exercise or medication routines unless directed by their personal doctors. As part of the crossover design, participants then went back to their baseline diets for a four-week washout period before switching to the opposite group for an additional 16 weeks.

Who lost weight over 16 weeks on each diet?

– Participants lost an average of 6 kilograms (or about 13 pounds) on the vegan diet, compared with no meaningful change on the Mediterranean diet.
–  Members of the trial lost 3.4 kg (about 7.5 pounds) more fat mass on the vegan diet.
–  They saw a greater reduction in visceral fat by 315 cm3 on the vegan diet.
– The vegan diet decreased total and LDL cholesterol levels by 18.7 mg/dL and 15.3 mg/dL, respectively, while there were no significant cholesterol changes on the Mediterranean diet.
– Systolic and diastolic blood pressure decreased more on the Mediterranean diet. decreased on both diets, 6.0 mm Hg, compared to 3.2 mmHg on the vegan diet.

Testing the diets head to head

weight loss Hana KhaleovaStudy author Hana Kahleova, MD, PhD, director of clinical research for the Physicians Committee, reported: “Previous studies have suggested that both Mediterranean and vegan diets improve body weight and cardio-metabolic risk factors. However, until now, their relative efficacy had not been compared in a randomized trial. 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.”

Vegan diets increase fiber and have fewer calories

The authors note that the vegan diet likely led to weight loss, because it was associated with a reduction in calorie intake, increase in fiber intake, decrease in fat consumption, and decrease in saturated fat consumption.

Why is fiber so important?

Plant-based diets are high in fiber. Fiber is often overlooked when it comes to healthy plates. Yet dietary fiber is an essential part of a healthy diet. It’s crucial for keeping the gut healthy and reducing the risk of chronic health conditions.

Most people in the United States do not get enough fiber from their diets. According to some estimates, only 5% of the population meet the adequate intake recommendations. This means that most people in the U.S. could get health benefits from increasing their daily fiber intake.

The diet crashed and burned when put to the test

Neal Barnard weight lossStudy author Neal Barnard, MD, president of the Physicians Committee also weighed in.  “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. In the 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 causes significant and consistent weight loss.”

Prior studies support this latest finding

A low-fat vegan diet led to significant weight loss, confirming the findings of prior studies.  Plant-based diets also reduce blood pressure, presumably due to reductions in blood viscosity and body weight, and their high potassium content.

The bottom line

The Mediterranean diet has many benefits, however, as Dr. Kahleova concludes,  “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.”


A Mediterranean Diet and Low-Fat Vegan Diet to Improve Body Weight and Cardiometabolic Risk Factors: A Randomized, Cross-over Trial
Received 23 Nov 2020, Accepted 22 Dec 2020, Published online: 05 Feb 2021
Gisèle Wertheim Aymes

Gisèle Wertheim Aymes

Gisèle is the owner of the Longevity brand. She is a seasoned media professional and autodidactic. Her goal? Sharing the joy with others of living in good health, while living beyond 100, You can follow her @giselewaymes on Twitter and Instagram or read her Linked-In profile for full bio details.


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