I have spent much of the last fifteen years reporting and writing about issues of public health, nutrition, and diet. I have spent five years on the research for and writing of this book alone. To a great extent, the conclusions I’ve reached are as much a product of the age we live in as they are my own skeptical inquiry. Just ten years ago, the research for this book would have taken the better part of a lifetime. It was only with the development of the Internet, of search engines and the comprehensive databases of the Library of Medicine, the Institute for Scientific Information, research libraries, and secondhand-book stores worldwide now accessible online that I was able, with reasonable facility, to locate and procure virtually any written source, whether published a century ago or last week, and to track down and contact clinical investigators and public-health officials, even those long retired.

Throughout this research, I tried to follow the facts wherever they led. In writing the book, I have tried to let the science and the evidence speak for themselves. When I began my research, I had no idea that I would come to believe that obesity is not caused by eating too much, or that exercise is not a means of prevention. Nor did I believe that diseases such as cancer and Alzheimer’s could possibly be caused by the consumption of refined carbohydrates and sugars. I had no idea that I would find the quality of the research on nutrition, obesity, and chronic disease to be so inadequate; that so much of the conventional wisdom would be founded on so little substantial evidence; and that, once it was, the researchers and the public-health authorities who funded the research would no longer see any reason to challenge this conventional wisdom and so to test its validity.

As I emerge from this research, though, certain conclusions seem inescapable to me, based on the existing knowledge:

1. Dietary fat, whether saturated or not, is not a cause of obesity, heart disease, or any other chronic disease of civilization.

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.

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.

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.

5. Obesity is a disorder of excess fat accumulation, not overeating, and not sedentary behavior.