A new study finds that following a Mediterranean-style diet rich in extra-virgin olive oil is 40 percent more effective in curbing the development of Type 2 diabetes than adhering to a low fat diet, even without efforts of weight loss.

Published in the Annals of Internal Medicine, the study followed a group of more than 3,500 Spaniards aged 55 to 80 who were at high risk of developing heart disease for about four years.The researchers divided the subjects into three diet groups: Mediterranean diet with extra-virgin olive oil, Mediterranean diet supplemented with mixed nuts, and low-fat diet. The subjects were not told to lose weight or increase their physical activity.

"Randomized trials have shown that lifestyle interventions promoting weight loss can reduce the incidence of type 2 diabetes, however, whether dietary changes without calorie restriction or increased physical activity also protect from diabetes development has not been evaluated in the past," Jordi Salas-Salvado, the study's lead author and a professor of nutrition at Rovira i Virgili University and the head of the Department of Nutrition at the Hospital de Sant Joan de Reus in Spain, wrote in an email to Reuters Health.

Those in the Mediterranean diet focused on eating fruits, vegetables, whole grains and fish but not olive oil while those in the nut group could eat about an ounce of walnuts, almonds and hazelnuts a day. Those in the olive group, on the other hand, were allowed a little more than three tablespoons of olive oil a day.

The result of the study showed that those who followed the Mediterranean diet were about 30 percent less likely to develop type 2 diabetes than those who followed a low-fat diet and those who supplemented their diet with olive oil were 40 percent less likely to develop diabetes than those who adhered to a low-fat diet.

"These benefits have been observed in participants between 55 to 80 years old at high cardiovascular risk," Salas-Salvado said. "Therefore, the message is that it is never too late to switch to a healthy diet like the Mediterranean."

Salas-Salvado also added that despite the apparent effectiveness of the Mediterranean diet in lowering risks of type 2 diabetes withou involving weight loss, cutting calories along with adopting a Mediterranean-style diet would likely cut risks even further.