The University of Michigan Health System study, published in Journal of the American Dietetic Association, found the women on the Mediterranean diet plan increased their consumption of monounsaturated "good" fats such as olive oil.

The six-month study divided 69 women into two groups. In one group, registered dietitians used an "exchange list" of foods common in a Mediterranean diet to make a plan for each participant that maintained the caloric and total fat intakes each women consumed at the beginning of the study. The dietitians also provided counseling on making dietary changes.

Women in the other group continued their usual diet and were offered one dietary counseling session after completing their part in the study.

Those following the exchange-list plan reached the goals of the Mediterranean diet within three months and maintained the change for the six-month duration of the study, but the comparison group made few dietary changes.

"That tells us that the exchange list was helpful in assisting women to make major changes in their diet, without changes in their caloric or total fat intake," study lead author Zora Djuric said in a statement.