The lessons we learn from nutritional science

My employer is concerned about the health of his employees and subscribed us all to a health newsletter. Every two weeks we receive some health tips in about ten to fifteen lines, based on the latest findings in health science. In the last newsletter, there was one article that jumped out on me. It was titled “Lots of fats or lots of carbohydrates?”. This is how it starts: (translated from Dutch)

Nutritional Sciences made large blunders in the past. For a long time, we had to avoid fats to stay healthy. Not only was this the wrong advice, it also has proved counterproductive.

In the 1950s, scientists drew the wrong conclusions from population studies. They focused on fats as the only cause of obesity and heart disease. Recent studies provide a more nuanced picture: a diet rich in fats and low in carbohydrates works at least as well to lose weight!

This sounded very familiar. Until a few years ago, fats were seen as something bad for our health due to our sedentary life styles and considered to be THE cause of obesity with loads of negative side effects like hypertension and heart disease.

The industry jumped in on the hype and began to produce “light” products among which products with less fats. Problem with this is that fats bring taste to the food, so to compensate for that, they added for example sugars. Now it was found that those sugars play a much greater role in obesity, hypertension, but also in other things like diabetes.

In that light, I could agree with the statement that it was not only the wrong advice, but also counterproductive. By trying to avoid the “negative effects” of fats, the experts exposed the public to a substance that is now believed to have actually a lot of negative effects, also those that were previously attributed to fats.

Wasn’t that a case of progressive insight? Scientists of last century obviously drew the wrong conclusions, but today’s scientists found out how it really worked and now come with a different recommendation? I believe that is true, but there is more to it. The experts, with help from the media, broadcasted their recommendations with certainty to the public. The same is true for this health tip. It basically said that the conclusions of the scientist from the 1950s were wrong, but now we know better and, hey, these are the new recommendations. They also didn’t mention the interesting history of this reversal.

Weren’t these things then not known until a few years ago? Not exactly. I heard about this hypothesis already in the 1980s, so why did it take so long to change the recommendations? The problem was that the scientists of last century claimed that there was a consensus on fats being bad for us and other scientists who didn’t adhere to this consensus were marginalized, vilified or neglected. The best known example is probably John Yudkin who proposed his hypothesis already at the end the 1950s.

In fact, the issue was brought to the public attention by skeptical outsiders, not by nutritional scientists. The experts were blinded by this apparent consensus and skeptical scientist were pushed out of the debate.

Before I continue, let me be clear that I don’t want to claim that eating a lot of fat is good for you. Dose is the key. Fats deliver certain essential nutrients and in that quantity are just fine. This post however is about the earlier consensus of fats in our food and how this consensus changed over the last few years.

I saw some large parallels with climate science:

• they both study a complex, coupled system (the metabolism of humans and the climate system)
• both are focused primarily on one specific element from that system (fats and CO₂)
• there is a self proclaimed consensus (on fats being bad for our health and CO₂ being bad for the climate)
• the message is brought with a certainty that is unwarranted for an observational science
• this consensus side is trusted by the government to make policy recommendations
• in both cases this consensus is defended viciously against those who think otherwise (not only with scientific arguments)
• the media and government play a big role
• skeptical scientists fearing for their careers, leaving it for a large part to skeptical outsiders to bring the issue to the public
• …

Okay, would you say, the fact that nutritional sciences made some serious errors in the past, doesn’t necessarily mean that climate scientists would be wrong now. True, the fact that nutritional sciences made errors in the past and that the consensus position was the reason why these errors were uncovered only many decades later, doesn’t prove that climate science is plagued with the same issues.

It however proves that a consensus on its own can not be trusted. It proves that scientists can be fooled by a consensus. Even all scientists of a particular field can be fooled by that consensus. Setting back development for many decades, giving bad advice to policy makers and wrong recommendations to the public for at least two generations, with unintended consequences as a result.

While I perceived the consensus as something natural in my believer’s years (if all scientists agree, it must be true), later it didn’t make much sense anymore. Especially considering climate science being a multidisciplinary field that is studying long term changes in a complex, coupled, chaotic system over a long time frame with only one subject and only reliable data for the last decades. Wouldn’t it then be more logical that more scientists disagree with each other? Claiming a consensus in a highly complex system with sparse data seems a downright miracle to me. Also, even nutritional sciences have the advantage of having lots more subjects to study (there are a lot of people) over climate science (which has only one system to study).

Concluding, from my current point of view, it is my firm impression that climate science is riddled with the exact same issues as nutritional sciences until a few years ago…

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