Good Calories, Bad Calories

body. The term was often used interchangeably with “atherosclerosis.”

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^*5 Decreasing cholesterol consumption from four hundred milligrams a day, the average American intake in the 1990s, to the three hundred milligrams a day recommended by the National Cholesterol Education Program would be expected to reduce cholesterol levels by 1 to 2 mg/dl, or a decrease of perhaps 1 percent.

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^*6 It did include a half-page of “recent scientific references on dietary fat and atherosclerosis,” many of which contradicted the conclusions of the report.

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^*7 Another of the seven was a reanalysis of a 1964 study that had compared the health and diet of Dubliners with those of their siblings who had immigrated to Boston. The 1964 incarnation of the study concluded that the Boston Irish consumed six hundred calories a day less than their Dublin siblings and 10 percent less animal fat, but weighed more and had higher cholesterol. Heart-disease rates were similar, but the Irish brothers lived longer. This study was then reinterpreted twenty years later by Lawrence Kushi, who worked in Keys’s department at the University of Minnesota. Kushi concluded that those men who reportedly ate the most saturated fat and the least polyunsaturated fat in the early 1960s had slightly higher heart-disease rates in the years that followed. Though “The Cholesterol Facts” described the reanalysis as producing “particularly impressive results,” Kushi himself had been less impressed: “These results,” he wrote, “tend to support the hypothesis that diet is related, albeit weakly, to the development of coronary heart disease.”

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^*8 When Dayton and his colleagues autopsied the men who died, they found no difference in the amount of atherosclerosis between those on the two diets.

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^†9 Ordinary milk was replaced with an emulsion of soybean oil in skim milk, and butter and ordinary margarine were replaced with a margarine made of polyunsaturated fats. These changes alone supposedly increased the ratio of polyunsaturated to saturated fats sixfold.

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^*10 The results were also presented at a conference of the American Heart Association in 1975. A small chart documenting the results, without explanation, was then published as an abstract in the journal Circulation, along with the other abstracts from the conference.

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^*11 A second randomized double-blind controlled trial—the Heart and Estrogen/Progestin Replacement Study—tested hormone replacement in twenty-three hundred women who had already had heart disease. It also found no benefit from the hormones and suggested an increased risk of heart disease, at least for the first few years of taking hormone-replacement therapy.

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^*12 Frantz’s Minnesota Coronary Survey was technically a pilot project for the National Diet- Heart Study.

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^*13 The investigative reporter William Broad suggested another version of this story in Science in June 1979. He said the Dietary Goals constituted a last-ditch effort to save McGovern’s Select Committee, which had required renewal every two years since its inception and was now facing a reorganization that would downgrade its status to a subcommittee of the Senate Committee on Agriculture. “They were fighting for their life,” Cortez Enloe, editor of Nutrition Today, told Broad. “Their tenure was up.”

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^*14 As Dietary Goals explained, “Fat supplies 9 calories per gram, whereas protein and carbohydrates, the other two energy sources, supply only 4 calories per gram…. Consequently, particularly for those not involved in heavy physical activity, the consumption of a diet deriving 40 percent of its calories from fat may result in a continual struggle to lose weight.”

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^*15 It also affirmed the suspicion that polyunsaturated fats might be dangerous, and so further diminished the role of margarines and corn oils in dietary recommendations.

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^*16 The Honolulu Heart Program offered an extreme example of this conflict in 1985. The study revealed that high-fat diets were significantly associated with a lower risk of total mortality, cancer mortality, and stroke mortality. On the other hand, the percentage of calories as fat and dietary- cholesterol intake were both associated with a higher risk of heart-disease death. Thus, the authors concluded that “these data provide support for the diet-heart hypothesis,” albeit with a caveat: “They also suggest that men with low fat intakes have a higher total mortality rate than men with higher fat intakes.”

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^*17 In 1997, the MRFIT investigators also reported that the men in the treatment group subsequently had more lung cancer than the controls. This was despite the fact that 21 percent of the men had quit smoking in the treatment group, compared with 6 percent in the usual-care group. Because it was hard to believe that quitting smoking increased rates of lung cancer, the MRFIT investigators suggested the possibility that the lower cholesterol levels in the treatment group “might explain [their] higher lung cancer mortality.” And, indeed, serum cholesterol showed a “marginally significant inverse association” with lung-cancer mortality. Nonetheless, the MRFIT investigators concluded that this was not a likely explanation for the results.

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^*18 The fourth author was Henry McGill, a pathologist who studied atherosclerosis in humans and in baboons, who says he had agreed unconditionally with the American Heart Association position on dietary fat since the early 1960s.

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^*19 Though women were clearly meant to adhere to the low-fat guidelines, they had not been included in any of the clinical trials. The evidence suggested that high cholesterol in women is not associated with more heart disease, as it might be in men, with the possible exception of women under fifty, in whom heart disease is exceedingly rare.

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^*20 Browner’s analysis also assumed that restricting dietary fat would reduce cancer deaths, which was speculative then and is even more speculative now.

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^*21 William Taylor, the Harvard physician who had done the first of the three analyses on the questionable benefits of eating less fat, was unimpressed with this argument. “Most patients don’t come into my office saying I really want to contribute to the public health statistics in this country,” he said. “If they did, I’d know what to do for them.”

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^*22 Melvin Konner has doubts about the conclusions. “Boyd and I probably did underestimate the amount of meat in the Paleolithic diet based on our extrapolations for hunter-gatherers,” he said. “I just don’t think it’s nearly as extreme as this paper claims.”

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^*23 They did not, however, lose any weight because of this, which is paradoxical, and an issue we will discuss later.

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^*24 This paradox could also include Switzerland. In 1979, Swiss public-health authories reported