View Single Post
Old 11th October 2007   #1
Senior Member
Join Date: May 2007
Posts: 238
Default The fallacy of diet "consensus"

Here's a rather brilliant article that's well worth reading, not only because it tears a strip out of the diet industry, but also because it exposes the very notion of scientific "consensus," and how utterly misguided such a consensus can be:

The basic revelation is this:

The notion that fatty foods shorten your life began as a hypothesis based on dubious assumptions and data; when scientists tried to confirm it they failed repeatedly.

In other words, there's zero evidence that starvation, self-deprivation, or denial is in any way beneficial to health. Quite the opposite.

But where the article really shines is when it identifies the social mechanism that leads to such a hypothesis becoming an established "fact" (when it's really just a myth): the notion of the scientific cascade of error.

The article explains this idea clearly, and I don't want to offer a half-baked precis, but the basic idea is that if one scientist reaches a faulty conclusion, then another echoes him (trusting that the first scientist's credentials confirm him as some kind of authority), then another follows, and another, until eventually, you have a chorus parrotting the first misguided theory, lending a false air of credibility in numbers to an idea that was wrong to begin with.

It's the scientific equivalent of mob behaviour, basically.

Here's another excerpt from the article:

Cascades are especially common in medicine as doctors take their cues from others, leading them to overdiagnose some faddish ailments (called bandwagon diseases) and overprescribe certain treatments (like the tonsillectomies once popular for children). Unable to keep up with the volume of research, doctors look for guidance from an expert — or at least someone who sounds confident.

In the case of fatty foods, that confident voice belonged to Ancel Keys, a prominent diet researcher a half-century ago...He became convinced in the 1950s that Americans were suffering from a new epidemic of heart disease because they were eating more fat than their ancestors.

There were two glaring problems with this theory, as Mr. Taubes, a correspondent for Science magazine, explains in his book. First, it wasn’t clear that traditional diets were especially lean. Nineteenth-century Americans consumed huge amounts of meat; the percentage of fat in the diet of ancient hunter-gatherers, according to the best estimate today, was as high or higher than the ratio in the modern Western diet.

Second, there wasn’t really a new epidemic of heart disease. Yes, more cases were being reported, but not because people were in worse health. It was mainly because they were living longer and were more likely to see a doctor who diagnosed the symptoms.

Cut to a few decades later, and thanks to the cascade of error, dieting has become the medical cure-all. But it turns out that this cure-all doesn't cure anything:

when the theories were tested in clinical trials, the evidence kept turning up negative. As Mr. Taubes notes, the most rigorous meta-analysis of the clinical trials of low-fat diets, published in 2001 by the Cochrane Collaboration, concluded that they had no significant effect on mortality.

Mr. Taubes argues that the low-fat recommendations, besides being unjustified, may well have harmed Americans by encouraging them to switch to carbohydrates, which he believes cause...disease. He acknowledges that that hypothesis is unproved, and that the low-carb diet fad could turn out to be another mistaken cascade

So one diet fad turns out to be futile, leading to another diet fad, which is also futile. And in the meantime, a woman lives her life needlessly depriving herself of the foods that she craves.

Better to enjoy life to the fullest, and to trust the body's natural instincts.
Graham is offline   Reply With Quote