This is an incredible book that, for me, completely redefined what constituted a healthy diet.



I completely believed the calories in/calories out model of dieting: that is, if you consume more calories than you expend, you will put on weight, and that you lose weight by expending more calories than you consume. That model was simple and made a lot of sense. But, Taubes convincingly argues, it is not just too simplistic, it is wrong.



What matters isn't the quantity of calories consumed, but their quality. Rice, potatoes, flour (including cakes, bread, pasta, etc.), sugar, and other refined, easily digestible carbohydrates are converted to simple sugars in our digestive systems. In turn, this sugar enters our blood streams and raises our blood sugar levels. Since high blood sugar is dangerous and fatal if not addressed, our bodies respond by producing insulin which causes that blood sugar to be converted into fat and stored in our fat cells. This is all basic high-school biology, and completely uncontroversial. Taubes, however, goes further and cites study after study that implicate the recommended "healthy" low-fat, high-carb diets as a primary cause of obesity, coronary heart disease, type 2 diabetes, hypertension, certain cancers and a whole range of other health problems. He explains the mechanisms that lead to these diseases, and punches holes in the accepted wisdom behind recommended "healthy" dietary guidelines.



I was on a long, domestic flight when I read an in-flight magazine article by Taubes about this book back in early 2008. I was very skeptical, because what he had written flew in the face of what I had come to believe about health and diet, but I was intrigued because of the claims he made about the links between diet and hypertension. I had recently been diagnosed with hypertension (high blood pressure) and my doctor had put me on a course of medication to bring it under control. He had also told me to cut out as much sodium from my diet as possible. When I asked my doctor what I needed to do to come off the medication completely, he told me there was nothing I could do and that I probably needed it for the rest of my life. I was in my early 40's and didn't like the sound of that at all! So I bought a copy of this book and read it from cover to cover.



It was a revelation!



He cited studies which indicated that hypertension was caused by eating a diet rich in easily digestible carbohydrates. Such a diet raises blood sugar, which in turn raises insulin - in order to convert that sugar to fat, thereby reducing blood sugar, and storing the resulting fat in the bodies fat cells. However, the research indicated that insulin also had other effects on the body, one of which was to cause the kidneys to reabsorb more water back into the blood stream. In other words, insulin acted as an anti-diuretic. The resulting excess water increased blood pressure. (One of the drugs in my blood pressure medication was a diuretic, so it clearly worked by reducing the amount of water in my bloodstream.) At the same time, Taubes pointed out that blood sodium levels, which conventional wisdom claimed was the cause of that excess water (again, without a great deal of evidence to support it), was quite easily regulated by the kidneys and passed out of the body in urine.



This made a lot of sense to me, and so I started a diet that the book indicated would be healthier: one without starchy food, but with fish, meat, dairy products and green vegetables. Within days, I started getting muscle cramps and dizzy spells, and saw my doctor about the problem. It seemed that the combination of the diet and my hypertension medication was giving me low blood pressure and dehydration symptoms. He halved my medication dosage, instructed me to buy a blood pressure monitor, and to come off the medication altogether if my symptoms continued - but to check my blood pressure regularly. In the end, I stopped taking the medication, and my blood pressure was routinely around 118/75. So much for having to take the medication for the rest of my life.



But other effects were happening to me while I was on this diet. I started losing weight (I was, I'll admit, slightly obese when I started the diet), yet I never felt hungry, and could seemingly eat as much as I liked, without ever feeling bloated or full. This was supposedly one of the primary benefits of the diet and one of the main points of the book, but I was still surprised with the results.



Taubes' research also predicted that such a diet would do the following to my blood lipids: it would lower triglyceride levels, raise HDL ("good" cholesterol) levels and possibly raise LDL ("bad" cholesterol). Over the course of a year, the blood work performed by my doctor backed this up: I significantly lowered my triglyceride levels, significantly raised my HDL levls - both unequivocally good things - while slightly increasing my LDL levels. Taubes' studies had indicated that HDL levels had a strong inverse correlation with coronary heart disease incidence (that is, the higher the HDL levels, the lower the risk of coronary heart disease), while LDL had a weak, positive correlation, so I wasn't too concerned about the increase in LDL.



So, it worked for me.



However, this is not a book primarily about diet. It might be more accurate to say that it's a book about the science of diet, nutrition and health, and Taubes is happy to acknowledge that we still need to do a lot more research on the subject, but without any preconceptions. Indeed, throughout the book, Taubes points out the lies, errors, misinterpretations and failed critical thinking that led to the current dietary recommendations of a predominantly low-fat, high-carb diet. If those recommendations are right, he asks, why are we seeing such an explosion in obesity, hypertension and type 2 diabetes diagnoses?



He certainly doesn't claim to have all the answers, but he does put a lot of pseudo-scientific diet & health claims to the sword - and he explains why. He convincingly argues that Ancel Keys' "lipid hypothesis" - that diets that are high in fat, and high in saturated fat in particular, cause coronary heart disease - not only has no evidence to support it, but is contradicted by the evidence that is available. Taubes also demonstrates that in all likelihood saturated fat, far from being unhealthy, is actually an essential component of our diets.



I highly recommend this book!