A Mediterranean-style diet on its own is linked to better health, but new research shows it’s even more powerful when combined with calorie reduction, regular exercise and weight loss support.
In the PREDIMED-Plus trial, the largest nutrition and lifestyle clinical study ever conducted in Europe, participants who followed the full lifestyle program had a 31% lower risk of developing type 2 diabetes compared with those who followed the Mediterranean diet alone. The findings were published in the Annals of Internal Medicine.
“We’re facing a global epidemic of diabetes,” said co-author Frank Hu, Fredrick J. Stare Professor of Nutrition and Epidemiology and chair of the Department of Nutrition at Harvard T.H. Chan School of Public Health. “With the highest-level evidence, our study shows that modest, sustained changes in diet and lifestyle could prevent millions of cases of this disease worldwide.”
The Mediterranean diet emphasizes fruits, vegetables, whole grains and healthy fats, with moderate amounts of dairy and lean proteins and little red meat. To test its effects alongside lifestyle changes, researchers assigned 4,746 adults aged 55 to 75 to either an intervention group or a control group. The intervention included a Mediterranean diet, about 600 fewer calories per day, moderate activity such as brisk walking and strength training and professional weight loss support. The control group followed a Mediterranean diet without calorie limits, structured exercise or guidance.
After six years, the intervention group lost an average of 3.3 kilograms (about 7 pounds) and reduced their waist size by 3.6 centimeters (about 1.4 inches), compared to 0.6 kilograms (about 1 pound) and 0.3 centimeters (about 0.1 inches) in the control group.
“In practical terms, adding calorie control and physical activity to the Mediterranean diet prevented around three out of every 100 people from developing diabetes — a clear, measurable benefit for public health,” said co-author Miguel Martínez-González, professor at the University of Navarra and adjunct professor of nutrition at Harvard Chan School.
The results suggest that even modest, sustained lifestyle changes, when paired with a healthy dietary pattern, can significantly reduce diabetes risk among people already at high risk because of age, weight or metabolic syndrome.
The study was funded by the European Research Council, the Spanish National Institute of Health, the Biomedical Research Networking Centre and the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.