This book is divided into three parts. Part I is entitled “The Fat-Cholesterol Hypothesis” and describes how we came to believe that heart disease is caused by the effect of dietary fat and particularly saturated fat on the cholesterol in our blood. It evaluates the evidence to support that hypothesis. Part II is entitled “The Carbohydrate Hypothesis.” It describes the history of the carbohydrate hypothesis of chronic disease, beginning in the nineteenth century. It then discusses in some detail the science that has evolved since the 1960s to support this hypothesis, and how this evidence was interpreted once public-health authorities established the fat-cholesterol hypothesis as conventional wisdom. Part II ends with the suggestion, which is widely accepted, that those factors of diet and lifestyle that cause us to fatten excessively are also the primary environmental factors in the cause of all of the chronic diseases of civilization. Part III, entitled “Obesity and the Regulation of Weight,” discusses the competing hypotheses of how and why we fatten. It addresses whether or not the conventional wisdom that we get fat because we consume more calories than we expend—i.e., by overeating and sedentary behavior—can explain any of the observations about obesity, whether societal or individual. It then discusses the alternative hypothesis: that obesity is caused by the quality of the calories, rather than the quantity, and specifically by the effect of refined and easily digestible carbohydrates on the hormonal regulation of fat storage and metabolism.

My background is as a journalist with scientific training in college and graduate school. Since 1984, my journalistic endeavors have focused on controversial science and the excruciating difficulties of getting the right answer in any scientific pursuit. More often than not, I have chronicled the misfortunes of researchers who have come upon the wrong answer and found reason, sooner or later, to regret it. I began writing and reporting on public-health and medical issues in the early 1990s, when I realized that the research in these critically important disciplines often failed to live up to the strict standards necessary to establish reliable knowledge. In a series of lengthy articles written for the journal Science, I then developed the approach to the conventional wisdom of public-health recommendations that I applied in this book.