Health kick 2 year update, and defending Ancel Keys

Something occurred to me during my transition to a low sugar diet. If you think about it, it makes no sense that cholesterol in eggs, or saturated fat, would be harmful to humans. Our species has been raising chickens for around 4,000 years, and surviving on fatty meat for tens of thousands of years. Sugar, on the other hand, only became a regular part of most people’s diets between the 17th and 19th Centuries. So if you were looking for something the body might not have evolved to be able to process, you’d suspect the sugar, not the fat. It turns out that Dr John Yudkin made the same argument in his now-famous books in the early 1970s. He was ignored, rubbished, and his career ruined.

The evidence is pretty much in at this point. Cholesterol is harmless — go ahead and eat eggs every day. Saturated fat is harmless too. If you watch, you can see the purveyors of dietary advice slowly backing away from their previous prohibitions: the official US government guidelines have quietly dropped the warnings about eggs, though they’re moving more slowly on saturated fat.

So how did nutrition science go so badly wrong? Research data was simply ignored when it contradicted scientists’ beliefs, even if it was extremely rigorous.

Now, it would be easy to blame the whole thing on Ancel Keys. Many are doing so, because the world likes a simple good vs evil story. Reality is a bit more complicated than that, though. Yes, his dataset was cherry-picked, but the missing data would still have allowed him to draw the same conclusions. Yes, the “Seven Countries Study” excluded France and Germany, but that was more for reasons of budget than conspiracy. Meanwhile, Keys was quite clear that cholesterol was harmless. As he wrote in 1956:

It is concluded that in adult men the serum cholesterol level is essentially independent of the cholesterol intake over the whole range of natural human diets.

His “Mediterranean Diet” isn’t a bad diet, but unfortunately Keys was wrong about the reasons why it’s healthy — and people who didn’t adopt a Mediterranean diet assumed that Keys’ theories about why it was good would apply to other diets.

Keys shouldn’t have dismissed Yudkin’s theories. Like discredited fraudster and former doctor Alan Wakefield, Ancel Keys accused his opponent of being in the pocket of big business, in Yudkin’s case the meat and dairy industries, writing “Yudkin and his commercial backers are not deterred by the facts; they continue to sing the same discredited tune.”

But overall, I think the recent Guardian article is wrong — it wasn’t a conspiracy, it was more one of those “madness of crowds” scenarios, where everyone latched onto bad science for different reasons.

That’s not to say that the sugar industry had nothing to do with it. As recently as 1999, The Guardian was gullibly reporting the assertions of The Sugar Bureau that the whole “sugar is bad for you” thing was a myth and was totally over.

For my part, it’s now just over two years since I switched to a low sugar diet. My weight has remained stable in the 76-79kg range, with the highs tending to follow soon after holidays like Christmas and Easter when I relax my sugar limits a little. I don’t count calories, and I allow myself all the non-fructose-containing carbs I want, though I aim for whole grains and minimally processed foods as much as possible. My body fat could be better, but is in healthy range for my age.

One thought on “Health kick 2 year update, and defending Ancel Keys

  1. I think that nutrition science in the last half century has been only a bit better than the “four humours” stage of medicine, when even (especially?) well-educated, conscientious doctors would do more or less the opposite of what was good for their patient (most notably, bleeding them). Using evolutionary logic to decide what to eat, while a little bit tricky due to disagreements about what precisely we ate and how far back you should go, is at least working on science (evolution and archaeology) that is more or less on the right track. Nutrition is an important topic for study, but like economics, just because the topic is important to study doesn’t mean the experts know what they’re talking about yet.

    The more interesting questions about nutrition now are on things like milk, wheat, and alcohol, which our ancestors 50,000 years ago weren’t eating but a few thousand years ago they were. I think the result is that some of us have the right genes/ancestors to digest them well, and others don’t, and that will eventually require us to get our DNA sequenced before we can get good advice on what to eat and not eat (or else just trial and error, and see what works for you).

    But, nobody’s ancestors were eating sugar long enough ago to have adapted to it, and pretty much everybody’s ancestors were eating eggs long enough ago to have adapted to it, so there evolutionary science should have trumped the nutrition decades ago.

Comments are closed.