The Mediterranean diet probably should be considered from a number of different angles forming a Mediterranean lifestyle. It is not a standard diet for it exists in various forms. Firstly, which fatty acids are important? It seems that both monounsaturates (oleic, n-9 family) and n-3 fatty acids are relevant. The latter may come from nuts like walnuts as a source of alpha-linolenate, as well as from fish. The place of fresh fruit and vegetables is a central recurrent feature. The diet has been found beneficial in non-mediterranean countries such as India in modifying the course of cardiovascular disease.
With regard to obesity and the metabolic (insulin resistance) syndrome (IRS), the situation is more complicated. Mediterranean countries do not appear to be less prone to obesity. However, a small study has shown that a mediterranean type of diet which is richer in percent fat (as monounsaturates) leads to a similar weight loss when compared to a more conventional low fat diet, with the additional advantage of being more "palatable" (increased compliance). N-3 fatty acids also influence many of the complications of the IRS by lowering triglycerides, blood pressure and improving the clotting profile. Weight loss of only 5-10% is sufficient to improve many of the abnormalities associated with the IRS, thereby decreasing the need for multiple drug therapy. However, even this "simple" goal is unattainable by the conventional medical approach (~5% long-term success), because treatment involves behavioral modification to what we would call the Mediterranean lifestyle and promoting motivation for a radical change in nutrition and exercise habits.
From a public health perspective motivating exercise is the most cost-effective intervention in managing the obesity epidemic. Therefore, exercise is (and correctly should be) placed at the bottom of the energy pyramid in order to emphasize its cardinal role in eating habits - with the motto that "fat and fit is better than lean and lazy". It is most relevant to note that most of the improvements associated with weight loss may be achieved through exercise even without weight change. A simple "exercise" in etymology shows that the Greek word "diaita (diet)" really refers to "lifestyle" more than solely caloric intake (diet) and thus, the Mediterranean lifestyle - rather than just concentrating on the diet - may have some special benefit in helping to achieve good health and longevity.
Elliot M. Berry
Hebrew University, Israel