Mediterranean diet and exercise cut diabetes risk by nearly one-third, even without much weight loss, study finds
A large six-year trial found that older adults who combined a Mediterranean diet with regular exercise were far less likely to develop type 2 diabetes than those who only changed their diet.
Researchers from Harvard and 23 Spanish hospitals studied more than 4,700 adults aged 55 to 75 with metabolic syndrome and excess weight over six years.
One group ate a traditional Mediterranean diet consisting of more fruits, vegetables, nuts and extra-virgin olive oil while limiting meat and added sugars.
Meanwhile, the other group ate a similar diet but also slashed their daily intake by 600 calories and followed physical activity recommendations that included about 45 minutes of aerobic exercise six days a week, balance and flexibility exercises at least three days a week, and strength training at least two days a week.
"The physical activity program included aerobic activities, such as brisk walking or any equivalent activity of moderate intensity (e.g. aquagym, biking, swimming, etc.)," Dr. Jordi Salas, one of the lead authors of the study and professor of nutrition and bromatology at the Rovira i Virgili University in Spain, told ABC News. "The dietitians adapted the recommendations to the participants' fitness and preferences."
Those who reduced calories and exercise showed a marked reduction in the risk of type 2 diabetes -- 31% -- despite only a small average weight loss of about six and a half pounds over the study period.
"In practice, a combination of modest weight loss, improvement in eating habits, and regular physical activity is likely to be more effective for diabetes prevention than focusing on a single factor," said Dr. Frank Hu, another one of the lead authors of the study and professor of medicine and chair of the department of nutrition at the Harvard School of Public Health.
The authors suggest that the potential anti-inflammatory effects of the diet may work together with the fat-lowering effects of fewer calories and more exercise to reduce the risk of diabetes.
"This study suggests that adding even small amounts of calorie reduction and movement can significantly enhance health benefits of the Mediterranean diet," Hu added.
The Mediterranean diet, ranked the world's best diet for the eighth year in a row by U.S. News & World Report in January 2025, may also help protect against Alzheimer's disease. A study published today in Nature Medicine found it lowered risk in people with genetic risk factors, adding to the diet's list of potential benefits.
"It is never too late to shift toward a healthy diet like the Mediterranean diet and increase physical activity levels to improve health status and prevent disease," Salas said.
Raihan El-Naas, MD, is a board-certified internal medicine physician and current endocrinology fellow at Weill Cornell Medical Center and Memorial Sloan Kettering Cancer Center and a member of the ABC News Medical Unit.
