Monday, November 09, 2015

Was It the Government That Was (Chiefly) Responsible for the Low-Fat Diet?

Nutrition science is (apparently) seriously revising its recommendations for the amount of fat we should have in our diets. In response, many of my libertarian Facebook friends have been posting things like, "See: never pay attention to government nutritional guidelines."

But was it really the government that drove these recommendations? My impression -- and I have not studied this history in any depth, so this is only an impression -- is that this was more a matter of nutrition scientists jumping to plausible conclusions with too little evidence at hand. Studies showed that the presence of cholesterol in the blood had a positive correlation with heart disease. Therefore, people should lower their cholesterol intake. This hypothesis proceeded on the sensible idea that if we suffer from having too much of X in our bodies, we should put less X into our bodies.

But nutrition and physiology are very complex subjects, and it seems that this plausible idea was not tested sufficiently. Perhaps the real problem is a genetic predisposition to accumulate cholesterol in the blood, and diet has little to do with this. Or perhaps something else entirely!

In any case, government health agencies did pick up this low-fat ball and run with it, perhaps foolishly. (I would never deny that government bureaucracies often behave foolishly!) But the public choice explanations I've seen for assigning nefarious motives to this decision don't make sense to me: there are meat and dairy lobbies as well as grain lobbies, and it's not clear why even the grain lobby would be behind the low-meat-consumption guidelines, since it takes much more than a pound of grain to produce a pound of meat.

Scientific hubris and a naive faith in expert pronouncements seem sufficient to explain what happened here: Does anyone more familiar with this history than me know a reason why this is not so?


  1. Try Gary Taubes: "what if it is all a big fat lie" From all the reading I have done on the subject the low fat is good reads like a bad example of Thomas Kuhn's paradigm shift I. Which it appears that politics played a mayor role. He argues that the traditional scientific wisdom since the 1800's had been that carbohydrates made you fat. "It was Ancel Keys, paradoxically, who introduced the low-fat-is-good-health dogma in the 50's with his theory that dietary fat raises cholesterol levels and gives you heart disease. Over the next two decades, however, the scientific evidence supporting this theory remained stubbornly ambiguous. The case was eventually settled not by new science but by politics. It began in January 1977, when a Senate committee led by George McGovern published its ''Dietary Goals for the United States,'' advising that Americans significantly curb their fat intake to abate an epidemic of ''killer diseases'' supposedly sweeping the country. It peaked in late 1984, when the National Institutes of Health officially recommended that all Americans over the age of 2 eat less fat. By that time, fat had become ''this greasy killer'' in the memorable words of the Center for Science in the Public Interest, and the model American breakfast of eggs and bacon was well on its way to becoming a bowl of Special K with low-fat milk, a glass of orange juice and toast, hold the butter -- a dubious feast of refined carbohydrates."

  2. Scientists do make errors, and this is indeed to be expected and encouraged, but (as you indeed note) it took a government to plaster this advice all over the country and in every classroom. To the extent that scientists misrepresented their justifiable confidence in the advice to the point they thought it reached the "tell everyone and make it policy" threshold, that was in fact an avoidable failure.

    It's likewise a failure not to use your clout to say "hey -- our current confidence level doesn't justify that food pyramid you're bandying about".

  3. I think it is even simpler. Faced with the unknown, we have to make our best guess according to what we know, even if that is precious little.

    1. But the nutritional advice failure was not merely a best guess! It was "my confidence on this is high enough that it should be the advice given to everyone, and FDA labeling policy should follow the health recommendations of this chart".

      It's understandable to make mistakes. It's not understandable to mis-state your confidence this badly! (And FWIW, I think that's largely encouraged by the "fake it till you make it", "every negative self evaluation is Impostor Syndrome" culture.)

    2. I am with Silas here: the sin of the nutritionists here was a lack of humility. If they had just said, "Our very preliminary findings show that perhaps a lower fat diet might help," I'd have no complaint.

      There is a theme here: the hubris of the rationalist planners. They didn't just try out a housing project or two, to see how they worked: nope! They bulldozed numerous slums and moved millions into these (as it turned out) atrocities. Rationalist forestry... ah, I'd better make this a post!


Euphemisms II

It's not just abortion where these euphemisms bug me either. I think it is sometimes OK to euthanize your pet, but... you did not "...