Low-Fat Lessons

The hardest thing for an authority figure to say is, “I don’t know.”

We often ask authority figures questions they really can’t honestly answer, but the very human response is for them to make an educated guess. People tend to demand an answer of some kind from an authority figure, and if one particular expert refuses to provide an answer, people go looking for an expert who will. When you combine these tendencies with the sweeping authority of the government, you end up with the potential for major errors.

For the last 30+ years scientists, doctors, nutritionists etc. have recommended a diet low in fat as a means of preventing heart disease and cancer. The federal government has integrated this recommendation into everything from dietary guidelines to requirements for school lunches.

A study published today in the Journal of the American Medical Association looked at the association between a low-fat diet and the risk of cancer and heart attack.The study is huge, following nearly 49,000 women over a period of over 8 years. What did the study find? It found that a low-fat diet had no statistically significant effect on either cancer or heart disease.

Can you say whoops?

The study has its limitations. The fat reduction of the intervention group was considered “moderate,” so the study doesn’t tell us much about more radical restrictions on fat intake. On the other hand, the fat-intake reduction is inline with that which most people could reasonably be expected to effect, so it probably represents the results that most people in the real world could expect. Given how broad the study is, if any even near-linear relationship existed between fat intake and the studied diseases it should have showed up.

I think the low-fat-diet concept is another example of public science running ahead of hard data. The social and political dynamics overwhelm scientific discipline. People want answers and authority figures want to provide them. Authority figures don’t want to say “I don’t know” and ordinary people don’t want to hear them say it. When the government got seriously involved in nutrition in the early ’70s it became a political imperative to provide an authoritative answer. After the political and medical establishment staked its reputation on the low-fat concept, it became that much more difficult to get it reassessed.

Many people pushed the low-fat idea not because the evidence backed it but because it conformed to their social and political prejudices. Low-fat diets appeal to puritanical moralists of all stripes. Leftists love to castigate the corporate world for providing a high-fat diet to ignorant masses. Blue Staters love to mock Red Staters for their presumed high-fat diets and so on. Indeed, for every study that people thought confirmed the idea there was easily one that refuted it. The idea that the benefits of low-fat diets were well proven came from the heavy marketing of cherry-picked studies.

The parallels between the low-fat-diet concept, other instances of failures of publicly significant science such as the “energy crisis,” and the current mania concerning global warming should be obvious. In all three cases we have authorities making definitive statements for which they have no solidly confirmed data. In all three cases, powerful political factions staked out public positions based on the experts’ pronouncements. In all three cases we have a social divide where the concept plays into the prejudices of one side while affronting those of the other.

As one of the study’s authors said to the New York Times:

“But Dr. Freedman, the Berkeley statistician, said the overall lesson was clear.
“We, in the scientific community, often give strong advice based on flimsy evidence,” he said. “That’s why we have to do experiments.”

When faced with a subject like global warming, where the only real test of the concept is the passage of time, we should be doubly careful.

17 thoughts on “Low-Fat Lessons”

  1. And there are usually mavericks.

    The late Atkins, may have been a fanatic & certainly made bucks, but he also may have been right – or at least not as wrong as the scientific/nutritional community repeatedly portrayed him.

  2. But, um, I’m not, (And I share this with the majority of the world’s population.) a postmenopausal women. And given that sex hormones are chemically related to fats, this may be significant. This study’s applicability to premenopausal women, and men, is at least questionable.

  3. Brett Bellmore,

    from the Times article:

    Although all the study participants were women, the colon cancer and heart disease results should also apply to men, said Dr. Jacques Rossouw, the project officer for the Women’s Health Initiative. Dr. Rossouw said the observational studies that led to the hypothesis about colon cancer and die-tary fat included men and women. With heart disease, he said, researchers have found that women and men respond in the same way to die-tary fat.

  4. I believe Harvard published a similar study in the late 1990’s. It concluded that there was no statistical relationship between eating fats and heart desease. (The study used 80,00 nurses.)

  5. Death is a zero sum game. It’s the classical pie chart we’ve seen since high school. If deaths decrease in one part of the chart, they’ll increase in another. Thus will be born another ‘epidemic’ for the special interest groups to sell their ‘guilt’ upon the masses.

    Just pull out an almanac. Go look at the Census data. Check every decade. Our life expectancy grows every time. The social security program is a demographic time bomb, because us old people aren’t dying like we use to. Do they blame that on the food we eat?

    Fact. We are all going to die. No one gets out of this life alive.
    Fact. Death is natural. Now, when was the last time the death certificates listed ‘old age’ as the cause of death. When you tag the event with something other than the natural process of decay, it becomes a tool of power for interest groups to leverage power over your life and society.

    “See, I have scientific facts on my side, now do what you are told” Whack, whack, whack [with a rolled up scientific article]

  6. Don, spot on. There’s much derision of the high-fat diets we consume today, unlike preceding generations’ diets that were principally carbohydrates. However, the high amounts of fat and protein we consume give us bigger, stronger bodies. We now die from diseases our forefathers rarely had a chance to die from, whereas our forefathers’ lean diets generally left them weaker as they aged. My dad was of age to enlist at the start of WWII. He died at nearly 82, smoking and drinking up until a couple of days before he died, when the cancer left him bedridden.

    I touched on that in an entry When the bottom line isn’t everything, mainly discussing how greater wealth creates more choices for the consumer, and allows us to live longer, happier lives.

  7. Geeze, Don, every heard of the naturalistic falacy? Who cares if death is natural? So’s smallpox! It’s still an abomination, which we ought to abolish as soon as we can. As Alan Harrington said, Hire the scientists, spend the money, and hunt death down like a dog. He was too early, but today we’re within sight of doing just that.

    Sure, I’m going to die some day. Hopefully of proton decay…

  8. IIRC, the number one factor for when someone will die is the age at which his relatives die, not lifestyle, not health.

    That being said, part of my fanatacism for exercise is that I want to be active when I’m older and not sedentary simply because I let things go now.

  9. This discussion reminds me of a joke a friend used to tell whenever there was a purported new scientific finding about causes of death:

    “Yeah, you know what’s really bad for you according to statistics? Being 100 years old.”

  10. THIS is also the conclusion of the Daily telegraph medical writer, James Lefanu. His book on medical history made the same bet, arguing along with Shannon, about its political element. Special interest perversion?

    Unfortunately, while people have gotten a handle on corporate blood sucking (thanks to Ralph Nader? or higher education?), the high priests of Science are yet to be granted equal recognition.

  11. Uh, it’s a little more complicated than that. Oh, I’m not talking about this topic in particular, which I am not particularly knowledgeable about, but experts and medicine. If say, an expert in a particular field of medicine says quite honestly, “I don’t know”, some referring clinicians and patients hate, hate, hate that and ‘shop’ until they find someone who says they do know, absolutely for sure, such and such. This, of course, encourages quite a lot of nonsense. Oh, it comes from within the field, as well. But it’s a complicated business, this assessment of what we know, how we know it, and what that means specifically for a particular patient.

  12. Oh, I’m an idiot. Of course you just said that at the start of your post, didn’t you? I guess I was trying to make a slightly different point and didn’t do it well: that authority figures, by trying to be obliging, often get themselves in trouble. That obliging-ness is a particulary tricky thing to deal with in what is essentially a service industry, which is what medicine is, so you have authorities who also have to cater to non-authorities in a very wierd kind of symbiosis.

    Sorry about my earlier comment.

    It’s one of those days already :)

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