The low-fat diet cascade
Finally the New York Times comes up with a halfway decent review of Gary Taubes’ book Good Calories, Bad Calories. In yesterday’s Science section John Tierney (obviously not a member of the Kolata/Brody/Burros coven) takes a serious look at Gary’s book and what it has to say about the mainstream medical/nutritional establishment’s recommendation to follow a low-fat diet.
Gary Taubes spends many pages in detailed analysis of how the mainstream went wrong in promulgating these incorrect recommendations for so many years despite the mountains of contradictory evidence. John Tierney brilliantly sums up the same situation in just a few paragraphs using a TV show most of us are familiar with as an example:
We like to think that people improve their judgment by putting their minds together, and sometimes they do. The studio audience at “Who Wants to Be a Millionaire” usually votes for the right answer. But suppose, instead of the audience members voting silently in unison, they voted out loud one after another. And suppose the first person gets it wrong.
If the second person isn’t sure of the answer, he’s liable to go along with the first person’s guess. By then, even if the third person suspects another answer is right, she’s more liable to go along just because she assumes the first two together know more than she does. Thus begins an “informational cascade” as one person after another assumes that the rest can’t all be wrong.
Because of this effect, groups are surprisingly prone to reach mistaken conclusions even when most of the people started out knowing better…
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 (the K-rations in World War II were said to be named after him). 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.
As Taubes points out in his book Keys was strong of personality and didn’t shy away from vociferously attacking anyone with whom he disagreed. And he didn’t just point out in a civil way that he though opposing opinions were incorrect and give the reasons why, he attacked vituperatively in medical journals and in person during conferences. He was the Anthony Colpo of his day resorting to personal attacks and innuendo with the difference being that Keys was widely respected by the mainstream and was on the cover of Time magazine(see above); he was like E.F. Hutton: when he spoke people listened (by the millions) despite the fact that what he said was balderdash. Other academicians feared his wrath so they more or less published their findings but didn’t publicly promote them. As a consequence the cascade started with Keys and he made sure that it kept going until it took on a life of its own that still breathes today. If you don’t think so, take a look at some of the reviews of Good Calories, Bad Calories.
(To see an example of what a swine Keys could be, take a look at this exchange. In 1973 a well-respected scientist named Raymond Reiser wrote a paper questioning the idea that saturated fat might be the danger Keys thought it was. (click here for full text) Keys lost no time in responding, accusing Reiser of being a liar and distorting the facts. (click here for full text) Reiser responded (click here), but others got the message: don’t fool with Keys unless you want the same treatment. You can see the same kind of invective today on the part of anyone who questions the lipid hypothesis in the medical literature.)
Tierney has a follow up piece today in the online version of the Times that delves a little deeper into the phenomenon of informational cascades:
The belief that low-fat diets prolong your life is one example of a cascade. The crusade against global warming is another — which is not to say that global warming isn’t real. Cascades can be based on correct beliefs as well as mistaken ones. The point is that large groups of people can reach a “consensus” without most of them really understanding the issue: Once a critical mass of people starts a trend, the rest make the rational decision to go along because they figure the trend-setters can’t all be wrong. The danger is that you end up with the blind leading the blind…
He goes on to quote from a prominent researcher in the field as to why the group consensus over time doesn’t lead to a correct result. In short, it’s because the choice is posed in binary or yes/no form.
It all comes down to the fact that many choices are primarily binary. Endorsing a diet or not endorsing it. Buying a gizmo or not buying it. Going to the restaurant here or not. Running from the lion or not. Chasing the blond girl at the bar or not.
See, prior to our work, researchers thought that the following corrective force would be at work: If I see one agency adopt the 100% low-fat diet, and I think it is a bad idea, I should endorse it only halfway–say, I would suggest a 60% low-fat diet. The next person could figure out from my half-hearted adoption that I wasn’t so favorable, either. If he has negative private views, his choice would become even less favorable (say, 10% low-fat diet). Pretty rapidly, the truth will win out as more and more people act and their actions tell everyone how strongly they believe the diet. They communicate their private views through their action.
What cascades have done is to show that as long as the main choice is binary, this logic won’t hold. There is no strong corrective force any longer. I don’t really have the choice of going 50% low-fat diet. I have the choice of endorsing it or not endorsing it. No one cares about the details of how I am endorsing it. They can only easily observe whether I am for it or against it. If I follow, then those coming after me can no longer learn anything (easily at least) from what I have been choosing as my recommendation.
This analysis confirms one of the suspicions I’ve held for a long time, namely that the most vociferous popularizer of the low-carb diet – Robert Atkins – was its worst enemy in terms of its gaining wide acceptance. Atkins was so personally cantankerous and made such hubristic pronouncements that most mainstream researchers couldn’t stand him and couldn’t bring themselves to admit that he was right about what he said. As a consequence they thought in binary terms: either the low-carb diet is good or it’s bad. And since Atkins is its main proponent and we hate Atkins, it’s bad. Even low-carb proponents didn’t particularly like Dr. Atkins. As I mentioned in a previous post, John Yudkin, a low-carb proponent if there ever was one, said of the Atkins book that its
chief consequence [may have been] to antagonize the medical and nutritional establishment.
Had Dr. Atkins been charismatic, friendly, approachable, in full command of the medical literature, and had he not made the bizarre and hubristic comments about repealing the laws of thermodynamics, I think low-carb would probably be the diet of choice right now, recommended by mainstream nutritionists instead of being viewed as a fad diet that is dangerous. The obesity and diabetes epidemics might have been avoided. I’ve learned from many conversations with various scientists that they just can’t bring themselves to say publicly that Atkins was right because they loathed him so much.
Read these two pieces by John Tierney and you’ll see why people jumped on the low-fat bandwagon; read Good Calories, Bad Calories to see all the information they had to ignore to do so.
To end this post I want to relate an instance where I was almost publicly embarrassed by the cascade effect. In 1989 I was on my first book tour for my first book. It was early in the tour and I was in Minneapolis in the middle of January and going on my very first live TV show that had a studio audience. The book I was promoting told people how to concoct a protein shake and use it as part of a protein-sparing fast regimen. It’s hard to realize now with the plethora of tasty protein shake drinks available that in the late 1980s these products didn’t exist. I came up with a way to use powdered milk, some commercially available protein powders (there were a couple available, but they were used to add to a whole lot of carbs to make body building products – without the sweetening, they were undrinkable) and a few other ingredients to make a pretty good low-carb protein meal replacement. On this TV show I was to make up one of the drinks in front of the audience and have several people try it live.
Needless to say I was a little nervous. I liked the stuff, MD liked the stuff, all the people who loved me told me they liked the stuff, but here I was going to give it to total strangers on live TV and get their opinions. I was in a sweat. I was in the Green Room feverishly making sure I had all the ingredients so that I could put it together without leaving something out. I wasn’t paying attention to the monitor showing what was going on on the show I was moments away from being on.
Unbeknownst to me there was a solar eclipse in process that the hosts of the show kept cutting to on an onstage monitor. As the eclipse progressed the monitor was showing the advancement of the moon across the sun. Of course the moon passing in front of the sun threw the moon’s shadow across the surface of the earth in places where the eclipse was visible.
The host had asked members of the audience what causes an eclipse. The first person asked responded that an eclipse was the shadow of the sun on the earth, which is, of course, idiocy because the sun is the source of light so it can’t be a shadow. As other people were asked the same question, they all fell into step and gave the same answer. This was the setup.
As my turn came and I (filled with angst about the protein shake I was going to make and unaware of the eclipse situation) walked out onto the set, the first thing I was asked after my introduction was something along the following lines:
Now we can get an answer to our question from a real scientist. Dr. Eades there is an eclipse going on right now and we’re all debating about what a solar eclipse really is. We all think it is the shadow of the sun moving across the moon, is that right?
I was caught totally off guard, and my first impulse was to agree with the consensus, but fortunately, I took a moment to think it through and said that No it was the moon moving across the sun. But I realized after how easily I could have gone with the consensus. And if I had thought that going against the consensus would have branded me as a fraud and an idiot, I might have gone along. Or if there had been a Harvard astronomer on the set and the announcer had said Dr. Eades, Dr. X here from the Harvard astronomy department has just told us that the eclipse is caused by the shadow of the sun on the earth, what do you think? I may well have agreed. Cascades can be powerful persuaders.
Oh, and just in case you’re wondering, once we got into the diet part of my appearance it went great. All the people really liked the shake I made, or at least had the decency to say they did on live TV.