A nutrition scientist reveals the missing piece of the Mediterranean diet

Of the many fad diets that plague us, one of the most persistent also happens to be a balanced, science-backed regimen. The Mediterranean diet, so called because of the cuisine associated with countries around the Sea, promotes high-fat, low-carb, and low-processed food eating.

The diet is characterized by whole grains, abundant fruits and vegetables, olive oil as the main cooking fat, and protein mostly from fish and legumes. But part of the diet’s success may come from a certain X-factor, something that can’t be quantified or tested in a clinical setting.

Where did the Mediterranean diet come from?

Arguably, the Mediterranean diet has existed as long as humans have lived and eaten around the Mediterranean Sea. When and how it became a popular diet for the rest of the world is another story.

In 1958, American physiologist Ancel Keys launched the Seven Countries Study. Keys aimed to find a relationship between diet and the prevalence of coronary heart disease in seven countries with contrasting lifestyles and diets: Greece, Italy, Spain, South Africa, Japan, and Finland. A crucial connection he pursued was how dietary fat affected cholesterol levels in the blood. He found that participants from Japan, Greece, and Italy had the lowest incidence of not just coronary heart disease but all-cause mortality. Curiously, Japanese participants had a low-fat diet, yet the Mediterranean groups (Greece and Italy) had a higher-fat one. In particular, the diet was effective in elderly people who didn’t smoke, regularly exercised, and drank alcohol moderately.

Starting in the 1960s, what we now know as the Mediterranean diet took off.

What makes the Mediterranean diet healthy?

While the term “healthy” is relative, this diet’s pillars come from its emphasis on fresh fruits and vegetables, legumes, nuts and seeds, fatty fish, moderate alcohol consumption, and avoidance of ultra-processed foods and sugars. The diet is high in monosaturated fats, what most people call the “healthy” fats, high in fiber, and it has a low glycemic index.

In May 2022, an article published in The American Journal of Clinical Nutrition directly compared the keto and Mediterranean diets. In this study, 40 participants with prediabetes or Type 2 diabetes spent 12 weeks on the Mediterranean diet and another 12 on the keto diet. One of the study’s authors, Christopher Gardner, a nutrition researcher at Stanford University, notes that during both diets, participants lost significant amounts of weight, had better control over their glucose levels, and had lower triglycerides (a value that reflects the fat content in the blood), though the keto portion had even lower triglycerides. On the other hand, keto seemed to raise LDL cholesterol.

It was the follow-up he found interesting. Twelve weeks after both trial diets concluded, Gardner and his team checked in to see which diet habits participants stuck with. Most were eating a more Mediterranean diet, which he believes is because the keto diet is more restrictive.

Is there more to the Mediterranean diet than food?

As interesting as this comparison is, Gardner thinks there’s something missing from the discussion about why the Mediterranean diet works, and it has nothing to do with the food.

Gardner recalls a publication called the Nutrition Action Healthletter by the Center for Science and the Public Interests. He remembers about 20 years ago, when fad diets were peak-trendy, the Healthletter’s cover story featured the diet.

“They said, ‘The Mediterranean isn’t just a diet — it’s a way of life,” he says. The cover, he tells Inverse, evoked western European behaviors — walking for hours every day, eating a huge lunch, taking a three-hour nap, meeting friends late at night for a light dinner and glass of red wine.

The idea is that in addition to the food you eat, it’s the way you eat and live. This image of the Mediterranean diet is about enjoying not only food but life itself. There’s no need to restrict or ban certain foods, and eating is a joyful, communal practice. The glowing health benefits arise from the diet itself, as well as from living a highly connected, low-stress life.

However, Gardner notes, it’s hard to quantify things like joy. As such, it’s hard to test multiple factors associated with life satisfaction the way one tracks multiple macros in a diet.

But there’s some support that there’s more to a healthy diet than the food itself. This notion comes from what’s now known as Blue Zones, or communities around the world where people live longest and healthiest. Gardner recalls from the data that centenarians from Blue Zones had two big commonalities: a relaxed, physically active lifestyle — and beans. High in protein and fiber and low in fat, beans seem to make sense, and that can be easy to track. Even physical activity is easy to track. But relative levels of relaxation and satisfaction with life can be hard to measure as it impacts one’s diet.

“I can’t really randomly assign you to be at peace with yourself and nature,” Gardner says.

Why is it still around?

According to Gardner, the key to this diet’s staying power is simple: “It tastes good.”

There’s no need to sacrifice carbs or fat. It’s flexible and inclusive, as Gardner notes because the Mediterranean diet can encompass Greek, French, Italian, Turkish, and Middle Eastern foods.

As recently as 2018, nutrition researchers are still digging into the science behind the Mediterranean diet. In 2013, the PREDIMED (Prevención con Dieta Mediterránea) study, investigating the effects of the Mediterranean diet in more than 7,400 people, was published. They found an inverse relationship between the diet and risk of cardiovascular disease, as Keys had, and compared them against a group who had been assigned a low-fat diet.

In 2018, the researchers amended their study after PREDIMED had been retracted, though Gardner still considers the original paper legitimate and influential. What’s more, the reissued paper came to the same conclusions.

While it still may be a fad diet, the Mediterranean regimen’s benefits lie in its non-restrictive nature and the value that it’s not only possible to live a healthy life while enjoying food, but that it’s, in fact, integral.