Good Calories, Bad Calories

I strongly recommend Good Calories, Bad Calories, by Gary Taubes.  If you haven't heard of it, the subtitle is, "Challenging the Conventional Wisdom on Diet, Weight Control, and Disease," and that is an understatement!  This book turns everything you thought you knew about nutrition on its head, or at least attempts to. 

First, I want to thank all of you who recommended this book to me.  I have been liberated from my fear of fat!  I knew that I did better eating protein versus carbohydrates, but I still thought I should eat lean meats and low fat dairy products to minimize fat, both for weight control and to keep my cholesterol down.  Even after reading Taubes' NYT article, What if it's Been a Big Fat Lie, I didn't quite get it.  Here is the inescapable truth: there is no correlation between dietary cholesterol and heart disease.  There is not even a clear correlation between the "bad" cholesterol in your blood, LDL, and heart disease.  And a correlation would only be a start anyway - as you know, correlation does not equal causation.  There is a correlation between the "good" cholesterol, HDL and heart disease: the more HDL, the less heart disease.  There are also some good theories for causation that fit with the studies that show this correlation, although they are not proven yet (in my opinion).  Still, nothing supports the conventional wisdom that suggests limiting fat in the diet--simply nothing.  The original correlations have withered away with conflicting data.  The theory has gotten consistently weaker through time.  Read the book - the evidence from the studies could not be clearer.   

Taubes has a much more ambitious purpose than just to debunk the conventional wisdom, though.  His goal is to inspire more formal study of the harmful effects of refined carbohydrates and sugars in the diet.  Overall, I agree that this absolutely needs to be done, but I think, along the way, Taubes ends up making some of the same mistakes he identifies in the low-fat advocates.  He puts too much faith in observational studies and anecdotal evidence.  I was much more convinced by his skepticism than his positive thesis.  To be more specific, I'll use the author's summary of his own conclusions based on the evidence he collected, and put in my two cents (in italics):

1. Dietary fat, whether saturated or not, is not a cause of obesity, heart disease, or any other chronic disease of civilization. (Emphasis added.) I'm not convinced that "disease of civilization" is a valid concept but otherwise, I agree with this statement as a general rule for obesity and heart disease. This is where I think Taubes is brilliant and revolutionary.  His meticulous collection and presentation of the relevent studies is impressive and convincing.  

2. The problem is the carbohydrates in the diet, their effect on insulin secretion, and thus the hormonal regulation of homeostasis--the entire harmonic ensemble of the human body. The more easily digestible and refined the carbohydrates, the greater the effect on our health, weight, and well-being. This is where I think he goes too far, but I fully agree that there is enough evidence to treat this as a theory to be studied further. Further, I think it is enough to justify my own effort to reduce my carbohydrate and sugar consumption, but in a much more limited way than Taubes might recommend. I might even call it "probable" that carbohydrates are a big problem in a modern diet. But to call carbohydrates "the problem" is going too far based on the evidence he has presented.

3. Sugars--sucrose and high-fructose corn syrup specifically--are particularly harmful, probably because the combination of fructose and glucose simultaneously elevates insulin levels while overloading the liver with carbohydrates. I don't think there is all that much evidence for HFCS being even more harmful than sugar (although there is enough to warrant further study), but what impressed me in his discussion of sugar is the mammoth amount of sugar consumed per capita in our country now - I can't find the figures but it went from approximately 10 pounds a couple hundred years ago to well over 100 pounds per year now. Otherwise, my comments on #2 apply here.

4. Through their direct effect on insulin and blood sugar, refined carbohydrates, starches, and sugars are the dietary cause of coronary heart disease and diabetes. They are the most likely dietary causes of cancer, Alzheimer's disease, and the other chronic diseases of civilization. I would put the qualifier "most likely cause" on the first set of conditions and "a possible cause" on the latter. Note that Taubes says "dietary cause," not "cause." This means: as effected by diet. Taubes does not deny the interaction of genetic factors or other environmental factors. He is speaking strictly about effects from the diet. But, again, with the diseases of civilization! I think that would only be a valid concept if, in fact, the earlier part of this statement was proved correct. In other words, if we did prove that carbohydrates and sugars caused diseases x,y,z, and we found that those diseases cropped up with the introduction of those foods in various diets, then we would have a valid concept. Of course, we'd probably call it something different then, like, "diseases of refined carbohydrates" or something. Still, this is the first place I have ever seen (and I have looked all over the internet, including in academic articles) any evidence at all presented for the "diseases of civilization" concept. It seems to be so accepted that nobody bothers to explain or justify it. But Taubes did give a history of the idea and it was a fascinating and compelling set of anecdotal evidence, but I just don't think it's valid to speak of these diseases as a group (and the members in the group are not always clear either). I think that is dangerous assumption-making, and the kind of oversimplification that Taubes warns us about in the earlier parts of the book. (The term "civilization" is inflammatory, from an Objectivist's point of view, but really it refers to agriculture, which many consider to be the necessary precondition to civilization. It really angered me, though, when Taubes quoted somebody who said that agriculture may have been the biggest disaster in the history of man, or something to that effect. Now that is the kind of anti-man statement I've heard when reading about the Paleo diet, at least in implication. If there are indeed "diseases of civilization," they are still a small price to pay for our modern world! Also, as somebody pointed out in the comments here on my blog, if modern foods are causing health problems, the answer is more science, not reversion.)

5. Obesity is a disorder of excess fat accumulation, not overeating, and not sedentary behavior. Wow! This is another area where Taubes shook up my worldview. You just can't understand this unless you read the book and the mountains of circumstantial evidence for this statement. I would add a qualifier to this statement that says that obesity "may sometimes be" a disorder of excess fat accumulation...or possibly, "may usually be." I still believe some (many?) people are overweight because they eat too much, even when their internal nutritional needs are met, but Taubes presents a plausible theory (see details below), there is evidence for it, and it fits with my own experience.

6. Consuming excess calories does not cause us to grow fatter, any more than it causes a child to grow taller. Expending more energy than we consume does not lead to long-term weight loss; it leads to hunger. Again, you'll have to read the book to understand and believe this. The key is that you can eat and the calories can get stored in your fat tissue without giving your cells the energy they need, so that being overweight is actually a manifestation of internal starvation. See #7. There is much evidence for this, but again, it really is not proven yet, in my opinion.

7. Fattening and obesity are caused by an imbalance-a disequilibrium-in the hormonal regulation of adipose tissue and fat metabolism. Fat synthesis and storage exceed the mobilization of fat from the adipose tissue and its subsequent oxidation. We become leaner when the hormonal regulation of the fat tissue reverses this balance. If you haven't read the book this probably doesn't make much sense to you, but it is intelligible in the context of the science presented in the book.

8. Insulin is the primary regulator of fat storage. When insulin levels are elevated-either chronically or after a meal-we accumulate fat in our fat tissue. When insulin levels fall, we release fat from our fat tissue and use it for fuel. Again, maybe. I learned a lot about the role of insulin by reading this book and it was fascinating.

9. By stimulating insulin secretion, carbohydrates make us fat and ultimately cause obesity. The fewer carbohydrates we consume, the leaner we will be. I wish, but again, I only give this a maybe.

10. By driving fat accumulation, carbohydrates also increase hunger and decrease the amount of energy we expend in metabolism and physical activity. Overall, I am pretty confident there is some truth to this theory, but I'm not convinced it is as clear-cut as Taubes suggests and I definitely do not think the evidence warrants cutting out most carbohydrates from one's diet, regardless of the costs in enjoyment, convenience, and price.

Much of the reason I say there is not enough evidence for many of these claims is that there have never been any real studies testing the hypotheses!  Taubes claims that the fat hypothesis is so ingrained and accepted that to even undertake a test of these theories would be blasphemy, so to speak.  To Taubes' credit, he calls the ten statements above his "own conclusions" and specifically calls for controlled studies.

I found the early part of the book the most interesting, where Taubes makes it clear that the erroneous fat hypothesis became gospel through a mixture of bad science, inertia, and government interference.  He goes as far as to say:

It's possible to point to a single day when the controversy was shifted irrevocably in favor of [the fat] hypothesis--Friday, January 14, 1977, when Senator George McGovern announced the publication of the first Dietary Goals for the United States.  The document was "the first comprehensive statement by any branch of the Federal Government on risk factors in the American diet," said McGovern.

This was the first time that any government institution (as opposed to private groups like the AHA) had told Americans they could improve their health by eating less fat...The document itself became gospel. It is hard to overstate its impact.

Another interesting issue is the concept of public health.  In a chapter called "The Greater Good" Taubes traces how the desire to "achieve the greatest good by treating entire populations rather than individuals" leads to patients who are not motivated to change their behaviors, which in turn leads to "experts" who exaggerate risks and try to create social pressure to change people's behavior, whether it is good for any particular individual or not.  Recognizing that this is an instance of collectivism at work really helps to understand the succession of "public service messages" we receive about health, which invariably are later revoked.  Think about the campaign against salt, or the outrageous exaggerations of the anti-drug campaign.

I could write even more about this book but I'll end with my own conclusions.  I do not think that carbohydrates are bad in the way that Taubes does so I suppose that I fundamentally disagree with the book.  (It is, after all, called "Good Calories, Bad Calories.")  I think the balance is off in the standard American diet--it is slanted too much towards carbohydrate consumption, in part because of convenience (which is a value) and in part (more recently) because of the low-fat campaign.  (Taubes specifically takes issue with the idea of a "balanced diet," claiming that the concept comes from the errors in the fat hypothesis, but I don't agree.  Because I do not think there is enough evidence, I default to a principle which fits with all my other knowledge about health, and life in general for that matter.)  For now, I'm not so much reducing carbohydrates as adding fats back into my diet.  For me, that means that carbohydrates are falling away more naturally, since I don't really like to eat much of them anyway.  I'm really just retraining myself to stop thinking in terms of fat being bad.  Once you see the Big Fat Lie for what it is, you will be shocked at how ingrained it is into your psyche.   I intend to trust my body's signals more than I have in the past, and to be even more skeptical (if that is possible) about nutritional studies.