That carbohydrates are uniquely fattening was the scientific consensus from the early 19th century through most of the 20th. The biochemical rationale for this easily observable phenomenon, known as metabolic syndrome, was thoroughly documented by German researchers in the 1920s and 1930s, and it has never been refuted. The culprit, according to this evidence, is the role of insulin in regulating fat accumulation, which enables an overabundance of carbohydrates to disrupt the balance between burning fats and storing fats within the cell.

 

So why, beginning in the late 1970s, did the United States government start recommending that we increase our consumption of carbohydrates? And why is that same government now surprised and alarmed that we have an “epidemic of obesity,” a serious health problem whose origins can be traced to that same period?

 

Gary Taubes, a long-time correspondent for Science and the only print journalist to have won three Science in Society Journalism Awards from the National Association of Science Writers, explores the history, as well as the science, of our current preoccupation with bad eating habits and their impact not just on obesity, but on diabetes, heart disease, and cancer. Taubes, whose previous book was Bad Science: The Short Life and Weird Times of Cold Fusion, assigns the science of nutrition, if not the science of epidemiology, to the same circle of hell in which he places Fleischman and Pons’ spurious work on low-energy nuclear reactions.

 

Having spent three years mining the literature from the 1920s up to today, Taubes presents evidence that fat is not the culprit behind obesity, heart disease, and many other of our ills. Cholesterol, he says, is similarly misunderstood. It became a target largely because it could be easily measured and, after the introduction of statins, managed with prescription drugs. According to Taubes, conventional wisdom about cholesterol and fat is based on flawed epidemiology, careerist logrolling, political solidarity, arrogance, conflict of interest, and a distinctive American Puritan streak that insists that the obese are lazy and lack will power.

 

Since the 1950s, the primary challenge of Western medicine has been its confrontation with the so-called “diseases of civilization.” Early in that decade, the epidemiologist Ancel Keys noted an apparent health discrepancy between populations who ate traditional diets, and populations whose fat-rich diets reflected the bounty of Western prosperity. “Eating well” on red meat and other fatty foods was associated with an alarming rise in the incidence of heart disease, at least according to Keys. His note of alarm was picked up by emerging leaders in nutrition, a field that had thrived in Europe, but which had been disrupted by the rise of fascism. After World War II, the discipline got a “fresh start” in North America, especially at Harvard University, where it was heavily financed, Taubes notes, by Kellogg, Nabisco, Frito-Lay, and the sugar industry.

 

Keys’ denunciation of fat in the diet coincided with an “epidemic” of heart disease, announced by Paul Dudley White, a famous cardiologist who was, at the time, consulting with the ailing President Dwight Eisenhower. (White’s pronouncement was conjecture at best. Other data suggest that there were simply more 50-year-olds who had survived the era of deadly infectious diseases and malnutrition and could now die from heart attacks.) Next thing you know, the American Heart Association, after demurring for some time, endorsed low fat, and Keys appeared on the cover of Time.

 

But then pressure from the public health establishment added to the confusion. In the 1970s, leading epidemiologists and nutritionists were asked to testify before the Senate Select Committee on Nutrition. According to Taubes, what these well-regarded scientists offered Congress was guesswork. Often, their testimony directly contradicted the research they cited.

 

But what emerged from their self-confident speculations seemed heartfelt and scientifically plausible; it was a line of argument that, even if specious, was easy to follow—a linear, simplistic thermodynamics: energy in through calories eaten, energy out through expenditure during exercise. They focused on the organism rather than the cell, ignoring the extensive body of German research on insulin regulation and metabolic syndrome.

 

These premature musings were picked up by the media, endorsed by the government, then enshrined in the ubiquitous “food pyramid,” used to illustrate that eating lots of grains and other carbohydrates—six to 11 servings a day—was the foundation of a healthy diet.

 

Again and again, Taubes describes exchanges with leading figures in nutrition in which he brings up the well-documented case for fat regulation in the cell. In these recent conversations, just as in their testimony before Congress 30 years ago, experts acknowledge the evidence that undercuts their position, then end the conversation by affirming their orthodox faith in low fat. It is like watching Inspector Clouseau not only fail to recognize the significance of the smoking gun sitting on the table, but time and again pick it up, admire it, feel its heft, and then put it back down, moving on to search for clues in the next room because the light is better there.

 

How the evidence was and continues to be mangled and disregarded is the most engaging, mystifying, and instructive aspect of his book. If Taubes is right, and his exhaustive use of the literature suggests that he is, the nation has been poorly served by “enthusiast virtue” as well as by the U.S. food industry. The problem of obesity has moved from a simple biochemical reaction to a question of the will, while starchy junk foods labeled “low in fat” and tanker cars of high fructose corn syrup flood the land.Politics, misguided consumer advocacy, and marketing have turned bad science and guesswork into certainty. As H. L. Mencken was wont to say, “There is always an easy solution to every human problem, neat, plausible, and wrong.”