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This belief in the fattening powers of carbohydrates can be found in literature as well. In Tolstoy’s Anna Karenina, for instance, written in the mid-1870s, Anna’s lover, Count Vronsky, abstains from starches and sweets in preparation for what turns out to be the climactic horse race. “On the day of the races at Krasnoe Selo,” writes Tolstoy, “Vronsky had come earlier than usual to eat beefsteak in the officers’ mess of the regiment. He had no need to be in strict training, as he had very quickly been brought down to the required weight of one hundred and sixty pounds, but still he had to avoid gaining weight, and he avoided starchy foods and desserts.” In Giuseppe di Lampedusa’s The Leopard, published in 1958, the protagonist, Prince Fabrizio, expresses his distaste for the plump young ladies of Palermo, while blaming their condition on, among other factors, “the dearth of proteins and the overabundance of starch in the food.”

This was what Dr. Spock taught our parents and our grandparents in the first five decades, six editions, and almost 50 million copies of Baby and Child Care, the bible of child-rearing in the latter half of the twentieth century. “Rich desserts,” Spock wrote, and “the amount of plain, starchy foods (cereals, breads, potatoes) taken is what determines, in the case of most people, how much [weight] they gain or lose.” It’s what my Brooklyn-born mother taught me forty-odd years ago. If we eat too much bread or too much spaghetti, we will get fat. The same, of course, is true of sweets. For over a century, this was the common wisdom. “All popular ‘slimming regimes’ involve a restriction in dietary carbohydrate,” wrote Davidson and Passmore in Human Nutrition and Dietetics, offering this advice: “The intake of foods rich in carbohydrate should be drastically reduced since over-indulgence in such foods is the most common cause of obesity.” “The first thing most Americans do when they decide to shed unwanted pounds is to cut out bread, pass up the potatoes and rice, and cross spaghetti dinners off the menu entirely,” wrote the New York Times personal-health reporter, Jane Brody, in her 1985 best-selling Good Food Book.

But by that time there had been a sea change. Now even Brody herself was recommending a diet rich in potatoes, rice, and spaghetti for the same purpose. “We need to eat more carbohydrates,” Brody declared. “Not only is eating pasta at the height of fashion…. It can help you lose weight.” The carbohydrate had become heart-healthy diet food. Now it was the butter rather than the bread, the sour cream on the baked potato that put on the pounds. The bread and the potato themselves were no longer the cause of weight gain but the cure. When a committee of British authorities compiled their “Proposals for Nutritional Guidelines for Health Education in Britain” in 1983, they had to explain that “the previous nutritional advice in the UK to limit the intake of all carbohydrates as a means of weight control now runs counter to current thinking….”

This was one of the more remarkable conceptual shifts in the history of public health. As clinical investigators were demonstrating the singular ability of carbohydrate-restricted diets to generate significant weight loss without hunger,*3 the mainstream medical establishment was insisting, as in a 1973 editorial by the American Medical Association, that the diets were dangerous fads—“bizarre concepts of nutrition and dieting [that] should not be promoted to the public as if they were established scientific principles.”

Just four months after the AMA publicly censured the use of these diets in The Journal of the American Medical Association, obesity researchers from around the world gathered in Bethesda, Maryland, for the first conference on obesity ever hosted by the National Institutes of Health. The only talk on the dietary treatment of obesity was presented by Charlotte Young, a well-known dietitian and nutritionist at Cornell University who had been studying and treating obesity for twenty years. Young first discussed the work of Margaret Ohlson, chair of nutrition at Michigan State University, who had tested carbohydrate-restricted diets in the early 1950s. “The diets developed by Ohlson,” reported Young, “gave excellent clinical results as measured by freedom from hunger, allaying of excessive fatigue, satisfactory weight loss, suitability for long term weight reduction and subsequent weight control.” She then presented the results of her research at Cornell, testing Banting-like diets on overweight young men. As in the other reports over the last century, she noted, her subjects seemed to lose weight by restricting only sugars and starches, without feeling any particular sense of hunger. Moreover, the less carbohydrates in their diets, the greater their weight loss, even though all her subjects were eating equivalent amounts of calories and protein. “No adequate explanation could be given,” Young reported, implying that further scientific research might be important to clarify this issue.

None would be forthcoming, and a century of empirical evidence would be rendered irrelevant, as the AMA’s spin on Banting’s low-carbohydrate diet as fad was quickly adopted as the conventional wisdom, one that has been adhered to faithfully ever since. Dietary fat had been identified as a probable cause of heart disease, and low-fat diets were now being advocated by the American Heart Association as the means of prevention. At the same time, the low-fat diet as the ideal treatment for weight loss was adopted as well, even though a low-fat diet was, by definition, high in the very carbohydrates that were once considered fattening.

This transformation is all the more remarkable because the medical authorities behind it were concerned with heart disease, not obesity. They presented no dramatic scientific data to support their beliefs, only ambiguous evidence, none of which addressed the efficacy of low-fat diets in weight loss. What they did have was the diet-heart hypothesis, which proposed that the excessive consumption of fat in our diets—particularly saturated fats—raises cholesterol levels and so causes atherosclerosis, heart disease, and untimely death. The proponents of this theory believed that Americans—and later the entire developed world—had become gluttons. Americans ate too much of everything—particularly fat—because we could afford to, and because we could not or would not say no. This overnutrition was certainly the cause of obesity. Eating too many calories was the problem, and since fat contains more than twice as many calories per gram as either protein or carbohydrates, “people who cut down on fat usually lose weight,” as the Washington Post reported in 1985.

A healthy diet, by definition, had suddenly become a low-fat diet. Beginning in the late 1980s with publication of The Surgeon General’s Report on Nutrition and Health, an entire research industry arose to create palatable nonfat fat substitutes, while the food industry spent billions of dollars marketing the less-fat-is-good-health message. The U.S. Department of Agriculture’s (USDA’s) booklet on dietary guidelines, and its ubiquitous Food Guide Pyramid, recommended that fats and oils be eaten “sparingly,” while we were now to eat six to eleven servings per day of the pasta, potatoes, rice, and bread once considered uniquely fattening.

The reason for this book is straightforward: despite the depth and certainty of our faith that saturated fat is the nutritional bane of our lives and that obesity is caused by overeating and sedentary behavior, there has always been copious evidence to suggest that those assumptions are incorrect, and that evidence is continuing to mount. “There is always an easy solution to every human problem,” H. L. Mencken once said—“neat, plausible, and wrong.” It is quite possible, despite all our faith to the contrary, that these concepts are such neat, plausible, and wrong solutions. Moreover, it’s also quite possible that the low-fat, high-carbohydrate diets we’ve been told to eat for the past thirty years are not only making us heavier but contributing to other chronic diseases as well.