THURSDAY, Aug. 27, 2020 (HealthDay News) — For a host of reasons, millions worldwide are deciding to give up meat and focus on a plant-based diet.

But new research out of Greece is a reminder that not all vegetarian diets are healthy — especially for people who are already obese.

“The quality of plant-based diets varies,” concluded a team led by Matina Kouvari of Harokopio University in Athens.

Reporting Thursday at the virtual meeting of the European Society of Cardiology (ESC), her team assessed the diets of 146 randomly selected obese people in Athens, who had normal blood pressure, blood cholesterol and blood sugar, and did not yet have heart disease.

Their diets were assessed using a questionnaire about their typical eating habits in the previous year. It asked about 156 foods and beverages commonly consumed in Greece.

Within 10 years, nearly half of the participants had gone on to develop high blood pressure, high blood cholesterol and high blood sugar — a combination that’s particularly risky for the heart.

However, diets focused on healthier plant-based foods were associated with normal blood pressure, blood lipids and blood sugar. These “healthier” vegetarian options included whole grains, fruits, vegetables, nuts, olive oil and tea/coffee, as well as foods made with the least amount of processing.

On the other hand, unhealthy plant-based foods — items such as juices, sweetened beverages, refined grains (for example, white bread and pasta), potatoes and any kind of sweets — were associated with developing high blood pressure, high blood cholesterol and high blood sugar, the team found.

“This finding was more evident in women,” Kouvari said in an ESC news release. “Prior research has shown that women tend to eat more plant-based foods and less animal-based products than men. But our study suggests that this does not guarantee healthier food choices and in turn better health status.”

Most dietary studies define plant-based diets simply as “vegetarian” or “low in meat,” which means all plant foods are considered equal, the researchers noted. But “our study highlights the variable nutritional quality of plant foods,” Kouvari said.

Sharon Zarabi is a registered dietitian who directs the bariatric program at Lenox Hill Hospital in New York City. Reading over the new findings, she agreed that simply going without meat won’t guarantee good health.

“Going vegetarian and avoiding meat will leave more room for highly processed carbohydrates, which raise insulin levels and make weight loss difficult,” she noted.

“Well-informed, nutrition-knowledgeable vegetarians looking to reduce insulin [which is a fat-storing hormone], reduce blood pressure, triglycerides and cholesterol will have to plan better to incorporate nuts, seeds, fish and eggs, depending or whether they are lacto-ovo vegetarians or pescatarians,” Zarabi said. In this way, they can “manage moderate protein levels and avoid adding excess carbohydrates,” she explained.

Whatever your diet regimen, the key is to make it “sustainable and enjoyable,” she said.

Because the findings were presented at a medical meeting, they should be considered preliminary until published in a peer-reviewed journal.