Excerpted from an article in the New York Times on January 6, 2023:

The Seven Countries Study, as it later became known, famously found associations between saturated fats, cholesterol levels and coronary heart disease. But the researchers also reported another notable result: Those who lived in and around the Mediterranean — in countries like Italy, Greece and Croatia — had lower rates of cardiovascular disease than participants who lived elsewhere. Their diets, rich in fruits, vegetables, legumes, whole grains, nuts, seeds, lean proteins and healthy fats, seemed to have a protective effect.

Since then, the Mediterranean diet has become the bedrock of heart-healthy eating, with well-studied health benefits including lower blood pressure and cholesterol, and a reduced risk of Type 2 diabetes.

What exactly is the Mediterranean diet?

The Mediterranean diet isn’t as much a strict meal plan as it is a lifestyle, said Julia Zumpano, a registered dietitian who specializes in preventive cardiology at the Cleveland Clinic in Ohio. People who follow the Mediterranean diet tend to “eat foods their grandparents would recognize,” Dr. Heffron added: whole, unprocessed foods with few or no additives.

The diet prioritizes whole grains, fruits, vegetables, legumes, nuts, herbs, spices and olive oil. Fish rich in omega-3 fatty acids, like salmon, sardines and tuna, are the preferred animal protein source. Other lean animal proteins, like chicken or turkey, are eaten to a lesser extent. And foods high in saturated fats, like red meat and butter, are eaten rarely. Eggs and dairy products like yogurt and cheese can also be part of the Mediterranean diet, but in moderation. And moderate alcohol consumption, like a glass of wine at dinner, is allowed.

Breakfast might be smashed avocado on whole-grain toast with a side of fresh fruit and a low-fat Greek yogurt, Dr. Heffron said. For lunch or dinner, a vegetable and grain dish cooked with olive oil and seasoned with herbs — roasted root vegetables, leafy greens, a side of hummus and small portions of pasta or whole grain bread, with a lean protein like grilled fish.

What are the health benefits of the Mediterranean diet?

A number of rigorous studies have found that the Mediterranean diet contributes to better health, and in particular better heart health, in a variety of ways. In one study, published in 2018, researchers assessed nearly 26,000 women and found that those who followed the Mediterranean diet most closely for up to 12 years had about a 25 percent reduced risk of developing cardiovascular disease. This was mainly because of changes in blood sugar, inflammation and body mass index, the researchers reported. Other studies, in men and women, have reached similar conclusions.

Research has also found that the diet can protect against oxidative stress, which can cause DNA damage that contributes to chronic conditions like neurological disease and cancer. And some studies suggest it can help reduce the risk of developing Type 2 diabetes.

Will the Mediterranean diet help with weight loss?

The diet can be conducive to weight loss, Ms. Zumpano said, but you’ll still need to pay attention to calories.

“Nutrient-rich foods aren’t necessarily low in calories,” said Dr. Heffron, who noted that the diet includes foods like olive oil and nuts, which are heart-healthy yet high in calories and can lead to weight gain if consumed in large portions. But if you’re changing your diet from one that is rich in calories, saturated fats and added sugars, for instance, with one that prioritizes vegetables, fruits and leaner proteins, that can result in some weight loss, he said.

The Mediterranean diet is not meant to be a hack for rapid weight loss, though. Rather, it should inspire a long-term shift in eating behavior. In one study of more than 30,000 people living in Italy, for instance, researchers found that those who followed the Mediterranean diet most closely for about 12 years were less likely to become overweight or obese than those who followed the diet less closely. A smaller study, published in 2020, enrolled 565 adults who had intentionally lost 10 percent or more of their body weight in the year prior. It found that those who reported adhering to the Mediterranean diet closely were twice as likely to maintain their weight loss as those who did not closely follow the diet.