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Low-Carb Shenanigans: The Battle Rages On …

January 23, 2011
In the previous Low Carb Shenanigans post I explained how I loved Gary Taubes’s book Good Calories, Bad Calories when I read it in early 2010 – then I started having doubts, these doubts were confirmed by various bloggers and by December 2010 I had a fairly low opinion of Taubes. In the same month his new book Why We Get Fat was released. I read it, and like I said in the previous post, it resolved some of the issues I had found with Taubes’s argumentations – so I thought that all was well, and that I could support Taubes again.
Well, as it turns out this was a bit premature – and it is also a more complex issue than “Taubes is right” or “Taubes is wrong”.
In a Nutshell
I think that he’s right about the lipid hypothesis – saturated fat and cholesterol don’t cause heart disease. He’s also right in pointing out that eating less starch/sugar is not only effective for weight loss, but can also be a health benefit if in exchange people eat more healthy fats (including saturated fat). But he goes on to make the claim that the “carbohydrate hypothesis” can be explained scientifically, and fails at doing so. We know through anecdotal evidence, historic common wisdom and blood panels that low-carb/high-fat works for many people, but we can’t yet explain exactly how it works (and whether it works for all people), and trying to make it appear like we can by cherry-picking or even misrepresenting (outdated) research, like Taubes seems to be doing repeatedly in GCBC, is in the long term not going to improve the mainstream acceptance of low-carb.

The Long Version
Let me first point out that GCBC has two main aspects:
1. The Lipid Hypothesis
This mainly deals with how saturated fat and cholesterol were established as causes for heart disease, and how this could happen when there never was any substantial evidence to back it up. Taubes brilliantly explains  the historic development and why even today mainstream MDs are still trapped in this flawed paradigm of fat/cholesterol metabolism.
2. The Carbohydrate Hypothesis
This is where things eventually go awry. Taubes tries to establish this dichotomy where it’s either “calories in / calories out” or carbohydrate which are to blame both for obesity and metabolic syndrome, and all the health issues these conditions entail. He corrects this to a large degree in Why We Get Fat – he explains that “calories in / calories out” is valid, but simply doesn’t explain causality. 
In my humble opinion he could have stopped with debunking the lipid hypothesis and it would have been a brilliant book. But he moves on and sets up his own hypothesis. Now he’s the one making a positive claim, and he needs to present evidence to support his hypothesis, which is that carbohydrates are the main cause for overeating/underexpending. He first produces a lot of historical evidence and shows that until the 1970s people “knew”, as part of conventional wisdom, that when someone is obese and wants to lose weight, starchy/sugary foods are what needs to be restricted. I’m with Taubes on that, and I think that this is again a point where he could have stopped and it would still have been a good book. But even then, as for example James Krieger pointed out in his blog, the Pima indians, which Taubes uses as an example of a peoples which developed diabetes and obesity when they started living off of ration packs (which contained primarily white flour and sugar) in reservations, backfire because there are Pima societies in Mexico who today still live on their original diet – which contains a lot of carbohydrate – and who don’t have problems with obesity and diabetes. This still leaves refined flour or sugar as possible causes, but in both cases it would not be digestible carbohydrate (glucose) which raises insulin which raises fat (according to Taubes) which could explain the problems with the Pima in the reservations.
Unfortunately, Taubes goes yet another step further and looks at the science of fat tissue regulation. And here I must definitely side with his critics: He seems to be cherry-picking research which supports his hypothesis, and ignoring that which doesn’t. He focuses on outdated research, claiming that “this all should have been obvious decades ago”  and suggesting that most modern research is flawed and can be ignored out of hand, because it is tainted by the lipid hypothesis. James Krieger made one very good general comment about why much of the old research is clearly inferior to current research: In the early 1900s much of the information about hormonal regulation of fat tissue was derived from in vitro experiments – researchers put cells in a petri dish, subjected them to various influences, and then observed the outcome. Today we of course have more sophisticated methods of observing cells in vivo, and I think we can all agree that human metabolism is a very complex system. Change any one variable, and most likely a list of other variables will change, and those changes will cause changes in yet more variables, creating many regulatory circles that are heavily interdependent. Observing cells that have been isolated from the entire organism can give you some information, but drawing conclusions from these observations about the entire organism is problematic.
Much of what Taubes says about insulin and how carbohydrate through insulin drives fat storage is not (or no longer) supported by actual science. There’s much truth to some particular facts he presents – insulin is indeed a storage hormone, and in many cases an increase in insulin may cause an increase in fat storage, and people who don’t have any insulin (type 1 diabetics) can’t store fat. But most people are not type 1 diabetics, and protein drives insulin as much as carbohydrate does, and many people thrive on high carbohydrate diets without getting fat.  The point is that his central conclusions from those isolated factoids are not sound. Sure, they sound good and they seem to make sense intuitively when you have the preconceived idea – which, like I said above, is supported by historical and anecdotal evidence – that carbohydrates are “uniquely fattening”. But often, when something sounds too good to be true, it’s actually not true.
As much as I hate to say it, in my opinion in GCBC Taubes is in many cases dishonest about the actual science of fat tissue regulation. I heard him say in a lecture that what he said about glycerol-3-phosphate may have been “skewed”:
“… although in all honesty whether it’s doing it as much as I believed it was when I wrote my book is now in question because some very smart young biophysicists who read my book went back to the literature I’ve never found and said that both what I’m saying and what the [endocrinology textbooks] are saying may indeed be a bit skewed.”
I was impressed that he admitted this publicly, but I think he simply removed the topic in subsequent presentations, and he also didn’t mention it in Why We Get Fat. Which is a good thing, but he still kept the “carbohydrate drives insulin drives fat” mantra and sort of swept the glycerol-3-phosphate under the rug.
Ultimately he’s doing low-carb a disservice when he tries to use flawed science to justify it. Granted, many people may start eating low-carb because of his book, their health will improve, and they’ll love him for it and won’t really care about such “fine points”. But I’d rather he made a post on his blog where he admits that much of the science cited in GCBC is actually outdated – or was even misrepresented by him on order to align with his preconceived hypothesis. Maybe he also made genuine mistakes or simply saw conclusions that weren’t really there … admitting that and moving on to refine your theories is what a scientist would do. I don’t think it’s too late for him to do that, but the longer he waits, the more he risks becoming yet another Ancel Keys.

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