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Recently I saw an article about a chef who has created a low-fat Mediterranean diet. Until now, I really did think that I had heard it all, but this is just so utterly bizarre that I sat stunned, staring at my computer screen for a minute or so. If ever there was a contradiction in terms it is the words "low-fat" combined with "Mediterranean diet." Reading about this chef, it's clear that this is another of those people who simply don't understand anything about nutrition.
One of the great benefits of our understanding about the Mediterranean diet is that it put to rest the myth that a low-fat diet is beneficial.
The idea of a low-fat diet came about as the result of faulty science in the 1980s. There are a lot of reasons for this, and I do believe that researchers at the time were working from the best information they had available to them. This culminated in 1990 with the work of Dr. Dean Ornish and a report in The Lancet on his research known as The Lifestyle Heart Trial. This was a small study that followed two groups of patients with documented heart disease. The control group received the "usual care" and the study group a low-fat diet. The results showed a regression of heart disease in the study group and the food world changed overnight.
All of the sudden everything was about consuming a low-fat diet - to the exclusion of everything else. This idea prevailed throughout the 1990s with a tremendous amount of diet research focusing on the concept. As the research results came in, however, it became clear that a healthy diet isn't about low-fat at all. When larger studies were done it became clear that the amount of trans-fats in foods and their contribution to heart disease was the issue. At the same time researchers were discovering that it was not so much the amount of fat but the ratio of quality monounsaturated fats and polyunsaturated fats to the amount of saturated fat.
Parallel to this research and supporting the conclusions were very large studies being performed in Mediterranean countries. About a dozen years after Dr. Ornish's work, the results were clear that a low-fat diet is not a good idea and may actually cause more harm than good. The target is around 35% to 40% of calories from fat (not 10%).
What changed was the explosion in good quality nutrition research over the last 20 years, but also people overlooked something important in Dr. Ornish's work. Not only was there instruction in a low-fat diet, but they were also instructed in a program to help the participants stop smoking, exercise and reduce stress. Because the study was so small, it's hard to know which of these may have had the most effect (although we know that all three are beneficial both by themselves and when combined with each other).
As a result of the confusion in the 1990s, the idea of low-fat diet often became confused with lowering cholesterol and there was for the longest time the idea that a low-cholesterol diet would actually lower one's serum cholesterol. This has been pretty much disproven now as well. While there are a small minority of people who will have their cholesterol profile affected by consuming a high cholesterol diet, for the majority of us consuming cholesterol in our diet simply doesn't matter.
The take home message here is that if you see a recipe or a product labeled "low-fat" or "low-cholesterol," be suspect. That's not to say that all reduced-fat products are bad, but choose wisely. Lower fat dairy products can be a good choice, but low-fat cookies or snack foods will usually have more calories than their "regular" versions.
Likewise, it's clear that there's no reason for you to be following a low-fat diet. Choosing the right fats is key.
Eat well, eat healthy, enjoy life!
Timothy S. Harlan, M.D.