Researchers at the University of Santiago de Compostela discovered a link between the Atlantic diet and a reduced risk of developing metabolic syndrome—a group of conditions that together heighten your risk of serious health problems such as heart disease. The findings were published this month in the journal JAMA Network Open. 

Amid the global obesity epidemic, one nutrition expert who wasn’t involved in the research tells Fortune the study’s lack of attention to calorie counting is important.

“They showed that just focusing on what you eat, without focusing on how much you eat, can pretty significantly improve your health,” says Dr. Dariush Mozaffarian, a cardiologist and director of the Food is Medicine Institute at Tufts University. “People think, ‘If I change my diet and I don’t lose weight, I’m failing,’ and that’s a mistake.

“You can substantially change your health—without changing your weight but by changing your diet—for better and for worse.”

What is metabolic syndrome?

Metabolic syndrome, also called insulin resistance syndrome, is a blanket term for a set of risk factors that collectively increase your chances of developing more precarious medical conditions including stroke, heart disease, and diabetes. Having at least three of the following constitutes metabolic syndrome:

• Abdominal, or central, obesity
• High blood pressure
• High blood sugar levels
• High blood triglycerides, which can raise “bad” (LDL) cholesterol
• Low “good” (HDL) cholesterol

It’s no surprise these well-established indicators would be most sensitive to a healthy diet, Mozaffarian says. 

Whereas drugs have a specific target, “nutrition pretty much affects every pathway in the body,” he says. “It’s the accumulated benefits across all those pathways that make a difference.”

About a third of U.S. adults have metabolic syndrome, which is largely preventable, according to the National Heart, Lung, and Blood Institute.

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What can you eat on the Atlantic diet?

The study refers to the Atlantic diet as “the traditional dietary pattern in northwestern Spain and Portugal, which is composed of home-cooked local, fresh, and minimally processed seasonal products.” Researchers note a high intake of these foods as a hallmark of the diet:

• Cheese
• Chestnuts
• Dried fruits
• Milk
• Seafood
• Starches, mainly bread and potatoes

A moderate consumption of meat and wine is highlighted as another differentiation between the Atlantic and Mediterranean diets. The eating styles share a high consumption of:

• Beans
• Fruits
• Olive oil
• Vegetables
• Whole grains

Atlantic diet vs. Mediterranean diet

Beyond the bounds of the study, however, the Atlantic and Mediterranean diets are virtually the same, says Sander Kersten, Ph.D., director of the Division of Nutritional Sciences at Cornell University, who wasn’t affiliated with the research.

“You focus on minimally processed foods, lots of vegetables, fruits, whole grains, beans, olive oil, and those kinds of things,” Kersten tells Fortune. “[The Atlantic] diet could be slightly higher in meat compared to the Mediterranean diet but, again, there’s no hard data to go by that defines and directly compares these two diets.”

Because the Atlantic Ocean is far bigger than the Mediterranean Sea and abuts several European countries alone, a true Atlantic diet would encompass more variation than the study suggests, Kersten says. 

Previous research has referred to the eating regimen of the northwestern Iberian Peninsula as the Southern European Atlantic Diet. A 2021 review in the journal Minerva Endocrinology called it “more than a diet, it is a lifestyle where exercise, simple cooking techniques, respect for traditions, and pleasure of eating accompanied are constants.” This eating style is also known as the Galician Atlantic diet; the autonomous community of Galicia is located in northwestern Spain.

The Mediterranean diet has been well-studied, and even recognized by Unesco as an Intangible Cultural Heritage of Humanity. This has led to confusion and frustration among regions and communities whose eating habits are just as nutritious, such as Japan’s Okinawa diet, Mozaffarian says.

“What we have discovered as nutrition scientists is that it’s not the Mediterranean diet, per se, that’s healthy, but the principles of what constitutes it,” Mozaffarian says. “There’s different cultural ways to get to that same healthy diet, and the principles are here in this paper: minimally processed, fiber-rich, and bioactive-rich plant foods.”

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How was the Atlantic diet studied?

This latest research is a secondary analysis of the Galicia Atlantic Diet study, a randomized clinical trial performed from 2014-15 in rural northwestern Spain. Subjects included 518 adults ages 18-85 across 231 families—all of Spanish ethnicity, Caucasian descent, and “moderate socioeconomic and educational levels.” Participants were 60% female, with an average age of 47. People with select conditions including dementia, pregnancy, and alcoholism were excluded.

People in the control group didn’t change their eating habits. Those in the dietary intervention group not only received regular food baskets but also benefited from a cooking class, written materials, and three nutrition education sessions. The amount of food they consumed was unrestricted. Variables including medication use and physical activity were recorded for both groups.

After six months, people who had adhered to the Atlantic diet showed a 68% reduction in risk of developing metabolic syndrome compared to those who didn’t alter their diet. People in the dietary intervention group also were 42% less likely to have an additional component of metabolic syndrome than those in the control group. In addition, the dieters showed a reduced risk of abdominal obesity and low “good” cholesterol.

The Atlantic diet didn’t have a significant effect on high blood pressure, high blood sugar levels, or high blood triglycerides. And while some participants from each group had metabolic syndrome at the beginning of the study but not the end, the diet wasn’t associated with a reduced risk in disease prevalence.

“What [the study] suggests is that adherence to the Atlantic diet—which is essentially the Mediterranean diet—can help people improve their health,” Kersten says. “In principle, that’s not a message that is new.”

Citing environmental health as a key component of the study, the researchers also found that the dietary intervention group didn’t have a significantly reduced carbon footprint compared to the control group. Even so, carbon emissions are just one indicator of environmental impact, Kersten notes, opening the door to future study.

“Water use or land use [gives] an idea of how sustainable a diet is, or how well a diet conforms to our sustainability goals that we’ve set forth in the world,” he says.

For more on the Mediterranean diet:

• Eating a Mediterranean diet could reduce your risk of dementia and lead to a longer life. Here’s how to get started
• A new study on the Mediterranean diet offers the strongest proof yet that it’s associated with healthy brain aging
• The 4 best diets for healthy aging that experts say will keep your brain sharp and your body healthy
• The 9 best foods for high blood pressure