I recently posted a link on Facebook to Gary Taubes' article about why the campaign to stop America's obesity crisis keeps failing, and my friend Scott raised the following issue:
Taubes may or may not be on to something. But, he comes off like an Intelligent Design guy, "The experts are wrong, and they can't handle the Truth that I'm bringing."
I agree that Taubes' writings sometimes have the feel of a crazy outsider fighting against the establishment. However, both my personal experience (as well as those of a number of friends) and my (non-expert) reading of the literature both suggest that Taubes is largely right on in terms of his critique of the standard dogma regarding weight loss, food, and health.
First, the testimonial. As I noted in a previous post, it was Taubes' writings that were largely responsible for pushing me towards the low-carb way of eating that I have followed for more than a year now. After cutting carbs way down (except for my daily dose of dark chocolate, which is non-negotiable), I lost 20 pounds of fat and have kept it off, without any sense that I am being deprived; I basically eat whatever I want whenever I want, as long as it's real food and paleo-friendly (i.e., avoiding refined sugar, grains, and seed oils). Most important, I feel great eating this way; in particular, whereas I used to get serious hunger pangs and energy dips 3-4 hours after eating, I can now easily fast for 24 hours without feeling particularly hungry. My wife Jen has also had an interesting experience on this diet. She has been able to maintain her weight or lose weight while never feeling hungry, whereas on our old carb-heavy vegetarian diet she was only able to lose weight through radical caloric restriction that left her constantly famished. Similarly, a number of friends and family members have found that they were able to lose a substantial amount of weight after reducing carbs, while still feeling like they were able to eat to satiety. I have *never* heard anyone say that they went on a low-carb diet and gained weight; more often, I have heard from people that they went on a low-carb diet and lost weight but then were afraid that all of the saturated fat was going to cause them to have a heart attack any day.
This brings us to one of the central points of Taubes' writings, which is that the standard story about what comprises a healthy diet, namely the link between heart disease, cholesterol, and saturated fat, is just plain wrong. If you want a good overview of his general narrative without reading the books, I would suggest three NY Times pieces: one on the relation between dietary fat and disease from 2002, a blistering critique of epidemiological research from 2007, and his piece "Is Sugar Toxic" from 2011.
There are a lot of claims in the Taubes books, and I have not looked into all of them. However, to the degree that I have looked into the claims that I found most important and relevant to my own diet, I have found them to all have fairly compelling scientific bases. The most important regards the relation between heart disease, cholesterol, and saturated fat. It is amazing how the supposed unhealthiness of dietary cholesterol and saturated fat has become a "fact" that is repeated almost reflexively (e.g., most recently I encountered it in Tyler Cowen's "An Economist Gets Lunch"). I think that in part it is due to the visual similarity of saturated fat in meat and the plaques that are seen in atherosclerosis; it's just too easy to believe that the saturated fat that we eat is "clogging our arteries." The data appear to say otherwise. First, it has been known since 1950 that serum cholesterol bears little relation to dietary cholesterol; the mechanisms behind this are laid out nicely in Peter Attia's recent series on cholesterol. Second, a large recent meta-analysis (including data from more than 347,000 individuals across 21 published studies) found no relation between saturated fat intake and heart disease or stroke. Similarly, a recent Cochrane Collaborative meta-analysis of intervention studies showed that there was no significant reduction of total or cardiovascular mortality due to changes in dietary fat. Although I think Taubes is correct in his arguments that epidemiological studies are hugely problematic (which I will discuss some other time), I trust these large meta-analyses much more than I trust any individual study (e.g., the China Study), especially when they show no effect (given all of the biases towards publishing positive effects). I have also put my money where my mouth is: I now eat a high-fat diet including full-fat yogurt, eggs, and bacon almost every morning. It look me several months to stop craving sugar, but I'm now perfectly happy to a dinner without dessert, and in fact I no longer have a taste for foods that are extremely sugary.
Another of Taubes' main assertions is that obesity is caused primarily by carbohydrates (fleshed out in his book Why We Get Fat). My feeling here is that obesity is an incredibly complex problem that involves both the body and the brain, and any story that tries to simplify it to a single component of our environment is bound to be wrong. That said, it's clear to me from the person experience described above that the "calories in, calories out" story is wrong, and that it does matter a lot what one eats, not just how much. There has recently been a big argument in the blogosphere recently between Stephan Guyenet and Taubes over the relative importance of peripheral factors (e.g., insulin's effects on fat storage) versus neural factors (e.g., the role of satiety hormones and reward pathways); both of them have staked out strong positions, and I think that the truth is likely to fall somewhere in the middle (as usual). As a neuroscientist I clearly think that the brain plays an important role; I won't talk more about that here, maybe some time soon. I have not dug very deeply into the science of feeding trials in animals, in part because my reading of several summaries of this work suggests that the details can be very tricky but very important. In particular, without a great deal of control over exactly what kinds of nutrients are in the food, it can be very difficult to make any conclusions from the data. There are however some individual studies in humans that do provide support for Taubes' claims. For example, the A to Z Weight Loss Study showed that subjects assigned to the Atkins diet lost more weight and had better metabolic outcomes than people assigned to low-fat/high-carb diets like the Ornish Diet. It's just one study, and it would be good to see more, but this along with my personal experience is enough to convince me.
Later in the discussion that I mentioned above, Scott made the following additional observation:
But the question remains, why doesn't the science on the cellular level ever reach the public health scientific community? I'm usually very skeptical when some sort of conspiracy is trotted out to explain the lack of uptake.
There are a lot of answers to this, which Taubes goes into great detail to discuss in his books. But the general problem is that science itself can be a slow-moving ship; when it gets drawn well off course (as it appears to have been by the anti-fat arguments of Keys and others), it can take a long time to get back, and even longer for that new scientific knowledge to get translated into medical education and practice. What is most striking to me is how studies whose data seem clearly inconsistent with the standard view are often presented in a way that suggests that they support the view, often by picking and choosing specific conditions. Taubes gives numerous examples of this, as does Denise Minger's detailed analysis of the China Study. I've also noticed it on a number of occasions when reading papers in this literature. Thus, unless one is reading the papers closely (or following others who do this), it can be easy to continue to think that the standard model remains valid; you just can't take the abstract (or even the results section) at face value. However, the fact that the rise in obesity has occurred alongside declining fat intake (coupled with increasing carb intake) over the last 40 years makes it pretty clear to me that the standard theory is just plain wrong, and that the carb theory is a viable alternative that needs to be studied more intently. Unfortunately, many of the thought leaders in this area continue to expound solutions based on the "calories-in/calories-out" and low-fat ideas that got us here in the first place.
