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  • A new study suggests that a low-fat vegan diet may be more effective than the Mediterranean diet for promoting healthy weight loss.
  • In the study, the Mediterranean diet did not cause significant changes in weight, insulin sensitivity or resistance, or cholesterol levels.
  • If these findings are accurate, people looking to lose weight and improve their overall health now have a more effective, eco-friendly option.

Many people advocate the Mediterranean diet, which involves eating plenty of fruits, vegetables, legumes, and olive oil while limiting the intake of saturated fat and red meat.

However, there is increasing evidence that following a vegan diet — by avoiding all animal-based foods — may offer similar benefits.

A 2020 review concluded that veganism is linked to at least 11 major health benefits, including a reduced risk of heart disease, diabetes, obesity, and cancer. In a recent study, researchers set out to compare the benefits of vegan and Mediterranean diets.

“Previous studies have suggested that both Mediterranean and vegan diets improve body weight and cardiometabolic risk factors,” says study author Dr. Hana Kahleova, Ph.D., director of clinical research for the Physicians Committee for Responsible Medicine in Washington, D.C.

“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. Kahleova adds.

This finding could be good news for people looking to reach or maintain a moderate weight, reduce their risk of cardiovascular disease, or improve various other health metrics.

It could also be good for the environment.

Plant-based foods produce far fewer carbon emissions and use less water and land to grow than animal products. Eating more plant-based foods and fewer animal-based foods may also help alleviate global hunger.

The recent study appears in the Journal of the American College of Nutrition.

In the 1960s, researchers started formally exploring the benefits of a so-called Mediterranean diet, a term that people initially used to describe a diet high in vegetable oils and low in saturated fats.

Today, the term Mediterranean diet describes traditional eating habits in the many countries bordering the Mediterranean Sea. Therefore, it encompasses regional, cultural, ethnic, religious, agricultural, and economic factors affecting how, what, when, and where people eat.

Based on the scientific evidence, it seems fairly clear that following a Mediterranean diet reduces the risk of developing cardiovascular disease.

The American Heart Association state that eating a Mediterranean-style diet may reduce the risk of heart disease, stroke, high cholesterol, high blood pressure, diabetes, and obesity. They also note that it may reduce the risk of dementia and improve brain health.

However, although the Mediterranean diet has become one of the most popular diets for overall health, experts know less about its effect on body weight and weight loss.

A few studies have explored the issue, but their results are difficult to interpret because the researchers often ask the participants to limit their caloric intake or change their exercise habits.

At the same time, new research is establishing a positive association between a vegetarian or vegan diet and various health metrics, including cholesterol, blood pressure, body weight, and blood sugar, among others.

People following a low-fat vegan diet avoid foods of animal origin — including meat, fish, dairy, and eggs — and foods high in fat, especially saturated fat.

It makes sense that a low-fat vegan diet would offer similar benefits to a Mediterranean diet. Both diets focus on consuming plant-based foods and avoiding red meats high in saturated fat and cholesterol.

The latest study was the first randomized trial to compare the efficacy of the two diets.

In the study, 62 adults with overweight ate either a low-fat vegan diet or a Mediterranean diet for 16 weeks. The researchers told the adults in both groups not to limit their calorie intake or make any other exercise or medication changes.

The participants following the Mediterranean diet ate according to the PREDIMED Study protocol. This protocol involves eating mostly vegetables, fruits, legumes, extra virgin olive oil, low-fat dairy, and fish while limiting red meat and saturated fat intake.

Individuals following the low-fat vegan diet avoided all foods of animal origin and limited their intake of fatty foods.

Following the 16-week period, the participants went back to their regular dietary habits for 4 weeks. After that, the groups switched, and the participants followed the other diet for another 16 weeks.

The study found that within 16 weeks, the low-fat vegan diet consistently produced:

  • an average weight loss of 13 pounds (lb), whereas the Mediterranean diet produced no mean change
  • greater loss of visceral fat than the Mediterranean diet
  • greater loss of fat mass (about 7.5 lb more)
  • average reductions of 15.3 milligrams per deciliter (mg/dl) in the levels of “bad” or low-density lipoprotein (LDL) cholesterol and 18.7 mg/dl in total cholesterol levels, while the Mediterranean diet produced no significant changes
  • reduced insulin resistance and increased insulin sensitivity, while the Mediterranean diet caused no significant changes

Both diets led to a drop in blood pressure, but the Mediterranean diet reduced it by about 6.0 millimeters of mercury (mm Hg), and the vegan diet decreased it by 3.2 mm Hg.

The authors claim that the low-fat vegan diet probably caused weight loss because most participants on the diet naturally reduced their calorie consumption. They also reduced their fat and saturated fat intake and increased their fiber intake.

The authors also noted that the Mediterranean diet allows people to eat high-fat foods, such as vegetable or nut oils, dairy products, and fatty fish.

The study had certain limitations. For instance, the researchers could not control how strictly the participants followed their diets.

Future studies also need to assess how low-fat vegan diets affect cardiovascular risk factors, such as unhealthy cholesterol and high blood pressure levels, over longer periods.

Regardless of these shortcomings, if true, these findings could help people lose weight and improve their health more effectively through their diet.

“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,” says Dr. Kahleova.