Sunday, February 26, 2006

Fat Chance You'll Hear About This

"The great tragedy of Science -- the slaying of a beautiful hypothesis by an ugly fact." -- Thomas Huxley

Of all the beautiful hypotheses in the temple of preventive medicine, the claim that low-fat diets could prevent cancer and heart disease is perhaps the most central. But the last few weeks have been more than a little unkind to the beautiful hypotheses of the lifestyle medicine crowd. In fact the ugly facts have been piling up fairly quickly.

In early January, a study published in the Journal of the American Medical Association reported that low fat diets produced only temporary, moderate weight loss.

Then along came another JAMA study early this year that showed that the consumption of omega-3 fatty acids did not significantly reduce the risk of cancer.

And finally, again in JAMA, there were the three attention grabbing studies which reported that low-fat diets failed to reduce the risks of heart disease, colorectal cancer and breast cancer.

There have been numerous attempts to spin these studies into something that they weren't -- clear, if weak, endorsements of low fat diets as protective for cancer and cardiovascular disease. But that evidence simply isn't there.

For example, in the breast cancer study, incidence rates between the intervention and comparison group did not show a statistically significant difference, meaning that any differences between the groups were indistinguishable from chance. Similarly, in the cardiovascular disease study, the "diet had no significant effects on incidence of CHD (coronary heart disease), ... stroke ... or CVD (cardiovascular disease)."

So whatever the hype about these studies showing "trends" toward the benefits of low-fat diets, the scientific results do not support those claims....

As even Barbara Howard, one of the principal investigators for the low-fat studies, admitted to Gina Kolata of The New York Times for her story this month "Low-Fat Diet Does Not Cut Health Risks, Study Finds," ''We are not going to reverse any of the chronic diseases in this country by changing the composition of the diet.'' Except for smoking, all of the advice about healthy lifestyle is based largely on indirect evidence, she noted.

Indirect evidence in science, though, is often no evidence at all. With the JAMA studies this month we have, in what Michael Thun of the American Cancer Society called the "Rolls-Royce of studies," studies that should have found evidence if there was evidence to be found.

Yet, these facts never appear to disturb the public health community. And the strong advice about low-fat diets based on very flimsy evidence continues, with reporters paying more attention to the alleged flaws in the studies as opined by the high priests of the low-fat faith than to what the studies actually say....

We've got some more naked emperors (or priests) wandering amongst us; the 'Pop' health/medicine/lifestyle industry, and the food packaging industry.

I read a book called 'The Zone Diet', some folk hate it, some swear by it, it suggests roughly equal parts protein, carbs and fats. I've been eating that way, more or less for ten years, cramming as much peanut-butter (un-hydrogenated) cookies, olives and guacamole in my gob as I can get just to get my fat content UP. It certainly raises my energy level, as did going back to eating beef, which I avoided for about six years.

Apparently I'm doing everything wrong but boy do I ever feel great.

Italics Mine


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