Good Calories, Bad Calories

In the early 1950s, clinical investigators began to characterize the physiological mechanisms that would underlie Cleave’s saccharine-disease hypothesis of chronic disease, and that could explain the appearance of diseases of civilization going back over a century—the basis, in effect, of this carbohydrate hypothesis. The research evolved in multiple threads that resulted in some of the most fundamental discoveries in heart-disease and diabetes research. Only in the late 1980s did they begin to come together, when the Stanford diabetologist Gerald Reaven proposed the name Syndrome X to describe the metabolic abnormalities common to obesity, diabetes, and heart disease, all, at the very least, exacerbated by the consumption of sugar, flour, and other easily digestible carbohydrates. Syndrome X included elevated levels of the blood fats known as triglycerides; low levels of HDL cholesterol, now known as the good cholesterol; it included hypertension, and three phenomena that are considered precursors of adult-onset diabetes—chronically high levels of insulin (hyperinsulinemia), a condition known as insulin resistance (a relative insensitivity of cells to insulin), and the related condition of glucose intolerance (an inability to metabolize glucose properly). Over the years, other abnormalities have been added to this list: the presence of predominantly small, dense LDL particles, and high levels of a protein called fibrinogen that increases the likelihood of blood-clot formation. Elevated uric-acid concentrations in the blood, a precursor of gout, have been linked to Syndrome X, as has a state of chronic inflammation, marked by a high concentration in the blood of a protein known as C-reactive protein.

In the last decade, Syndrome X has taken on a variety of names as authorities, institutions, and associations have slowly come to accept its validity. It is often referred to as insulin resistance syndrome. The National Heart, Lung, and Blood Institute belatedly recognized the existence of Syndrome X in 2001, calling it metabolic syndrome. It has even been referred to as insulin resistance/metabolic syndrome X, or MSX, by those investigators attempting to cover all bases.^*39 By any name, this metabolic syndrome is as much a disorder of carbohydrate metabolism as is adult-onset diabetes, and is certainly a consequence of the carbohydrate content of the diet, particularly, as Cleave would have predicted, such refined, easily digestible carbohydrates as sugar and white flour.

It wasn’t until the late 1990s that the evolving science of metabolic syndrome began to have any significant influence outside the field of diabetes, at which point the media finally began to take notice.^†40 The potential implications of metabolic syndrome for heart disease and other chronic diseases have only just begun to be appreciated by the research community. As a result, a hypothesis that emerged from research in the 1950s as an alternative explanation for the high rates of heart disease in Western nations has been accepted by medical researchers and public-health authorities a half-century later as a minor modification to Keys’s dietary-fat/cholesterol hypothesis, even though this alternative hypothesis implies that Keys’s hypothesis is wrong. The bulk of the science is no longer controversial, but its potential significance has been minimized by the assumption that saturated fat is still the primary evil in modern diets.