Friday, November 09, 2007

Quoting from Gary Taubes

Wherein tonight for dinner it's a slab of bacon washed down with a tub of mayonaise


I'm currently reading Good Calories, Bad Calories by Gary Taubes. Fascinating research and it's a continuation from his ground-breaking article from ma few years back, What if It's All Been a Big Fat Lie? (NY Times, July 2, 2002).

From chapter 1, The Eisenhower Paradox:
From the end of World War II, when the USDA statistics become more reliable, to the late 1960s, while coronary heart-disease mortality rates supposedly soared, per-capita consumption of whole milk dropped steadily, and the use of cream was cut by half. We ate dramatically less lard (13 pounds per person per year, compared with 7 pounds) and less butter (8.5 pounds versus 4) and more margarine (4.5 pounds versus 9 pounds), vegetable shortening (9.5 pounds versus 17 pounds), and salad oils and cooking oils (7 pounds versus 18 pounds). As a result, during the wors decades of the heart-disease "epidemic," vegetable-fat consumption per capita in America doubled (from 28 pounds in the years 1947-49 to 55 pounds in 1976), while the average consumption of all animal fat (including the fat in meat, eggs, and dairy products) dropped from 84 pounds to 71. And so the increase in total fat consumption, to which Ancel Keys and others attributed the "epidemic" of heart disease, paralleled not only increased consumption of vegetables and citrus fruit, but of vegetable fats, which were considered heart-healthy, and a decreased consumption of animal fats.

I'm only a couple of chapters into the book and I'm already wondering how many people Ancel Keys has killed with his bad science:
In 1957, Keys insisted that "Each new research adds detail, reduces areas of uncertainty, and, so far, provides further reason to believe" his hypothesis. This is known technically as selection bias or confirmation bias; it would be applied often in the dietary-fat controversy. The fact, for instance, that Japanese men who lived in Japan had low-blood cholesterol levels and loe levels of heart disease was taken as a confirmation of Keys's hypothesis, as was the fact that Japanese men in California had higher cholesterol levels and higher rates of heart disease. That Japanese men in California who had very low cholesterol levels still had more heart disease than their counterparts living in Japan with similarly low cholesterol was considered largely irrelevant.

Keys, Stamler, and their supporters based their belief on the compelling nature of the hypothesis supplemented only by the evidence in support of it. Any research that did not support their hypothesis was said to be misinterprested, irrelevant, or based on untrustworthy data. Studies of Navajo Indians, Irish immigrants to Boston, African nomads, Swiss Alpine farmers, and Benedictine and Trappist monks all suggested that dietary fat seemed unrelated to heart disease. These were explained away or rejected by Keys.

...Once having adopted firm convictions about the dangers of dietary fat based on his own limited research among small populations around the world, Keys repeatedly preached against the temptation to adopt any firm contrary convictions based on the many other studies of small populations that seemed to repudiate hus hypothesis.

Taubes quoted in John Tierney's Junk Food or Junk Science? (Round 1):
I have two comments about Jeff’s post. First, anyone who can tell you “with certainty” that MacDonald’s is bad for us is the kind of zealot who can be dangerous if taken seriously. He might believe it, and he might have good reason to believe it, but telling us “with certainty”? I don’t think so. I can give him numerous examples of populations with epidemics of obesity and diabetes that were fast-food-restaurant free. McDonald’s may be serving up foods or nutrients that are bad for us (as may be Starbucks, for that matter), but the negative effects will depend entirely on what people order and what they then eat.
Secondly, of course, Jeff’s assuming that saturated fat, sodium and calories are bad, all of which can be (and probably are) the victims of the same kind of cascade you’re talking about with trans fats. My concern about [Mayor Michael] Bloomberg’s ban of transfats is: What happens if the nutrition research community should actually get its act together, do the necessary research, and conclude that sugar (sucrose) and high fructose corn syrup, for instance, are considerably worse for us than trans fats? They’re no more natural, even if the former has a slightly longer pedigree.
Would Bloomberg ban the use of sugar in New York restaurants? That would be fun.

Random House promotional interview:
Q: Everywhere we look, from Cheerios boxes to New York City’s recent ban on trans fats, we see the message that minimizing dietary fat will help prevent obesity and heart disease. How did we come to believe this “conventional wisdom” and when/how did you begin to doubt it?

A: We first came to believe this fifty years ago primarily because a handful of medical researchers of very dubious quality came to believe it unconditionally. They managed to get the American Heart Association to go along, which in turn convinced the health reporters and the politicians and it spread from there. The evidence never came around to support it, but after a while nobody cared. Or at least they didn’t consider the copious evidence refuting the hypothesis to be an impediment to believing that it was true.I came to doubt it initially because I had interviewed some of these people when I was doing an investigative article for the journal Science on the equally unsubstantiated belief that eating salt causes hypertension. My previous two books were about how hard it is to conduct good science, how rigorous and skeptical the scientists have to be, and here I was interviewing these prestigious and respected medical authorities, and they didn’t seem to have a clue what real science was all about. I decided to look into the fat story, knowing nothing about it, simply because these people were involved and claimed to have played significant roles. What I found was the scientific equivalent of a house of cards. These people would do a study to test their beliefs and it would come out either negative or just ambiguous. Then they’d interpret it as supporting their preferred hypothesis—that all fat or just saturated fat was harmful—in light of the fact that there were other studies that also supported their beliefs. And when I looked at the other studies, those were equally ambiguous but were in turn interpreted as supportive because still other studies appeared to support the fat-is-bad hypothesis. And that’s how it went, all the way down and back to the beginning. To mix my metaphors, there was a lot of smoke, but never any fire.

5 Comments:

Blogger Pastor_Jeff said...

Really, all the best nutritional advice basically boils down to:

1) Everything in moderation, and
2) Don't eat way more calories than you burn.

It amazes me that an entire industry (and related lobbying groups) have sprung up to complicate and legislate what is basically very simple.

11/09/2007 03:05:00 PM  
Blogger GK said...

No, pastor_jeff, not _everything_ in moderation -- more good stuff than bad stuff. More whole food than refined. More vegetables than sugar. Much more water than alcohol. More saturated fat than poison mushrooms.

And by the way, just how is one supposed to know consciously how many calories one is burning?

11/10/2007 02:24:00 AM  
Blogger Ahistoricality said...

gk: wouldn't "more good stuff than bad stuff" be the very essence of moderation? Pastor Jeff didn't say "eat the same amount of everything": that would be absurd.

And the latest thing in cosmetic surgery? A calorie counter, usually installed just under the left nipple.

Or you can use the old-fashioned "eat less/exercise more if your weight starts going up."

11/10/2007 04:08:00 PM  
Blogger GK said...

Absurd, yes, but that wouldn't be the first time some one has made an absurd statement on the 'net. Just checking. Further to ahistoricality's comment about moderation, I agree I am being picky here. I definitely would not advise moderation of things that are good to eat (and getting consensus on even that is difficult). I would say eat as much as you like.

Taubes contends that we already have internal calorie counters, that hunger and weight are regulated, IF one eats the "good" things. He theorizes that this internal calorimeter goes out of whack when inundated with too much of the "wrong" carbohydrates -- and when it works properly we just do not gain weight.

11/10/2007 08:07:00 PM  
Anonymous Anonymous said...

I have seen this - patently absurd - mantra so many times and in a characteristic manner of parroting that I wonder whether there is somewhere someone from the Nutrition Mafia who spreads this defense meme. It's not the meme itself but the manner in which it is parroted. It is always the same, and trying to explain things is pointless.

11/25/2007 02:48:00 AM  

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