Everyone knows that eating fatty foods is bad for you, that high cholesterol causes heart disease and that we should all do some more exercise so that we can lose weight. How do I know that everyone knows this? Well, for one thing, this government website tells me so:
We all know too much fat is bad for us. But we don't always know where it's lurking. It seems to be in so many of the things we like, so it's sometimes difficult to know how to cut down.
...kids need to do at least 60 minutes of physical activity that gets their heart beating faster than usual. And they need to do it every day to burn off calories and prevent them storing up excess fat in the body which can lead to cancer, type 2 diabetes and heart disease.
See, it's right there in black and white. We all know too much fat is bad for us. Except... there are a lot of people who don't agree. Gary Taubes is one of them, His book, Good Calories Bad Calories (The Diet Delusion in the UK and Australia), sets out the case against what he calls the Dietary Fat Hypothesis for obesity and heart disease, and proposes instead the Carbohydrate Hypothesis: that both obesity and heart disease are caused by excessive consumption of refined carbohydrates, rather than dietary fat.
Taubes is very convincing. He explains how people have consistently recommended low-carb diets for weight-loss for the past 150 years. He explains how scientists roundly ignored studies that contradicted the link between high cholesterol and coronary disease. There are details of the mechanism by which eating refined carbohydrate affects insulin production, leading to obesity. He gives a plausible narrative for how the Dietary Fat Hypothesis came to be accepted scientific wisdom despite not actually being true (or supported by the majority of the evidence). He explains how studies of low-fat diets simply ignored overall mortality rates, reporting only deaths from heart disease, and how one study wasn't published because 'we weren't happy with the way it turned out'. All in all, the book is very convincing.
I expect a relatively large percentage of people on LW are already aware of this. Searching the LW archives for 'Taubes' gives several, mostly positive, references to his work (Eliezer seems to be convinced "Dietary scientists ignoring their own experimental evidence have killed millions and condemned hundreds of millions more to obesity with high-fructose corn syrup."). However, I do expect it to be news to some people, and I think it raises an important question. Given that everyone needs to eat something, we all need to decide whether we believe Taubes or whether we believe Change 4 Life.
Good Calories, Bad Calories is 601 pages of relatively small type, and contains 111 pages of references. Most of you probably don't want to read a book that long, and you definitely don't want to check all of it's references. Even if you did, Taubes openly admits that his book is attempting to argue for the Carbohydrate Hypothesis - he is trying to convince you, why should you be surprised if you find yourself convinced? (He claims not to be cherry-picking but then, he would, wouldn't he?) So how can you decide whether to trust the government or whether to trust some journalist with no training in biology? Even if you do decide to assess the evidence for yourself, how exactly should you go about it?
This is the key question of rationality. How can we believe what is true? And I think this makes a great case study - it's an area in which we all have to have a belief (or at least, act as though we have a belief) and one in which there is (or at least appears to be) genuine controversy as to what is true and what is not.
If you've already thought about this, do you believe Taubes' thesis, and how did you come to this conclusion? If this is the first time you've ever heard of Taubes, how far have you shifted your probability for the Dietary Fat Hypothesis based on reading this post? What more research do you intend to do to decide whether or not to continue believing it? How much weight do you place on the fact that I believe Taubes? On the fact that Eliezer believes Taubes (Eliezer, if your position is more nuanced than this, feel free to correct me)? How much did you update your beliefs based on what other commentors have said (assuming there have been any)?
Great post. Since I have had (a diluted form of) the position Taubes describes for a long time (since before I was exposed to OvercomingBias, much less LessWrong) I cannot speak too much about the influences from here but it is a useful exercise to to try to trace how I update my beliefs in practice.
Caveat: I know damn well that I suck at giving true reports on what really causes me to change my mind. Our self awareness isn't particularly motivated to be honest about such things. Nevertheless I can give a best estimate on what influenced me.
Yes. From what I can tell I formed the belief based on exposure to various experts that appeared to be Correct Contrarians. As someone who has taken an interest in a whole range of topics regarding health I have been exposed to experts in all sorts of fields that overlap with nutrition. It is not hard to distinguish between experts that seek out research to form accurate opinions and 'experts' who specialise in presenting authoritative beliefs. It is also not hard (given the right skillset) to independently verify the positions of such experts on their core positions. Basically none of those individuals support the idea that fat is the big culprit or a worse health risk than carbohydrate.
I know little about Taubes. I've seen him as a reference but most of my exposure has been to other authors.
Probably quite a lot. ie. I am currently studying pharmacology degree with the intent of doing research in loosely related areas. I will almost certainly learn more about that kind of nutrition so as to better understand my own specific topics of interest.
A moderate amount. Your presentation is credible and any report from an evidently educated reader that demonstrates an interest in epistemic knowledge and an understanding of bias carries weight.
Hmm. Eliezer does seem to be good at identifying correct contrarians so his position on such topics carries some weight. What carries even more weight is when Robin and Eliezer both support the same position - they have sufficiently different influences that agreement counts for something. I don't recall whether Robin has blogged about diet advice in particular but his writing on health topics in general give credence to this position either way.
To be honest probably not much. I participate in other forums with a much higher level of knowledge on this area. On health related topics where I have been disagreement with other commenters here I have updated far less than when I have disagreed on non-health topics.
Which forums?
ETA: You probably refer to Imminst.org, right?