What’s so magical about the Mediterranean Diet?

Forget the mouse studies. After a couple weeks of controversial and much-contested rat studies on the effects of carbohydrates on various aspects of metabolism and disease, here’s a study involving 200 newly-diagnosed, diabetic humans.  Half were told to follow a Mediterranean-style diet, rich in vegetables, whole grains, and monounsaturated fats from poultry, fish, and olive oil and limiting carbohydrates to 50% or less of total calories.

The other half were assigned to a “low-fat” diet, which also emphasized whole grains and discouraged sweets and high fat snacks. Fat was limited to 30% or less of calories and saturated fat to 10% or less of calories.

After four years, the Mediterranean group had lost more weight and was only half as likely to need anti-diabetic medications.

What’s the real difference here?

Notice that the macronutrient distributions between the two diets are not all that different. The Mediterranean diet was not terribly low in carbohydrates (although it’s being described in media reports as a “low-carb” diet). The low-fat diet isn’t really all that low in fat. The two percentages certainly aren’t mutually exclusive. In fact, it’s entirely possible that the distribution of fats, proteins, and carbohydrates between the two groups was very similar.  Nor can we necessarily chalk it up to refined versus complex carbohydrates.  Both groups were instructed to favor whole grains.

Perhaps it was just a matter of what the dieters were told to focus on.  The Mediterranean group was told what to eat: vegetables, fish, grains, olive oil. The low-fat group were told what to avoid: sugary snacks and high-fat foods.  Could it be as simple as casting dietary recommendations in terms of positives instead of negatives?

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