Good Calories, Bad Calories (49 page)

Through the 1960s, Mayer documented this relationship between energy intake, inactivity, and obesity in a series of human studies. He noted that high-school girls who were overweight ate “several hundred calories less” than those who weren’t. “The laws of thermodynamics, however, were not flouted by this finding,” he said, because the obese girls spent only a third as much time in physical activity as the lean girls; they spent four times as many hours watching television. Mayer studied adolescent girls at summer camp and reported that the obese girls expended “far less energy,” even during scheduled exercise periods, than their non-obese counterparts. He also studied infants. “The striking phenomenon is that the fatter babies were quiet, placid babies that had moderate intake,” Mayer reported, “whereas the babies who had the highest intake tended to be very thin babies, cried a lot, moved a lot, and became very tense.” Thus, Mayer concluded, “some individuals are born very quiet, inactive, and placid and with moderate intake get fat, and some individuals from the very beginning are very active and do not get particularly fat even with high intake.”

Mayer also believed that this link between physical inactivity and overweight explained another troubling conflict in the evidence. How could the prevalence of obesity and overweight be increasing in the 1950s if calorie consumption, according to USDA estimates, had dropped significantly since the turn of the century? (Recal the changing-American-diet story.)

Descriptions of typical meals in the nineteenth century, as Mayer noted, suggest they were enormous compared with what we eat today. Breakfasts of the British gentry of the late nineteenth century “frequently assumed prodigious proportions,” according to the anthropologist Eric Ross. In a typical country house, wrote one British authority in the late 1880s, breakfasts consisted of “fish, poultry, or game, if in season; sausages, and one meat of some sort, such as mutton cutlets, or filets of beef; omelettes, and eggs served in a variety of ways; bread of both kinds, white and brown, and fancy bread of as many kinds as can conveniently be served; two or three kinds of jam, orange marmalade, and fruits when in season; and on the side table, cold meats such as ham, tongue, cold game, or game pie, galantines, and in winter a round of spiced beef.” In the United States, according to the historian Hil el Schwartz, such enormous meals were also the norm: “The 75-cent special at Fred Harvey restaurants in the late 1870s included tomato purée, stuffed whitefish with potatoes, a choice of mutton or beef or pork or turkey, chicken turnovers, shrimp salad, rice pudding and apple pie, cheese with crackers, and coffee…. When life insurance medical directors sat down to their banquet in 1895, they had clams, cream soup, kingfish with new potatoes, filet mignon with string beans, sweetbreads and green peas, squabs and asparagus, petits fours, cheese with coffee, and liqueurs to fol ow….” Incredibly, Schwartz noted, these gargantuan repasts “were two or more courses and thirty to sixty minutes shorter than formal dinners of the previous era, and their portions were smal er.”

Having concluded that caloric intake had actual y fal en since the nineteenth century, Mayer pioneered the practice of implicating the sedentary nature of our lives as the “most important factor” in obesity and the chronic diseases that accompany it. Americans in the mid-twentieth century, as Mayer perceived it, were more inert than their “pioneer forebears,” who were “constantly engaged in hard physical labor.” Every modern convenience, from the car to the extensions on our telephones and even the electric toothbrush, only served to make our lives ever more sedentary. “The development of obesity (and of heart disease as wel as a number of other pathologic conditions),” Mayer wrote in 1968, “is to a large extent the result of the lack of foresight of a civilization which spends tens of bil ions annual y on cars, but is unwil ing to include a swimming pool and tennis courts in the plans of every high school.”

But Mayer’s hypothesis always had shortcomings. First, the association between reduced physical activity and obesity doesn’t tel us what is cause and what is effect. “It is a common observation,” noted Hugo Rony, “that many obese persons are lazy, i.e., show decreased impulse to muscle activity. This may be, in part, an effect that excess weight would have on the activity impulse of any normal person.” It’s also possible that both obesity and physical inactivity are the symptoms of the same underlying cause. This was a likely explanation for the inactivity and obesity that Mayer had observed in his laboratory mice. The same genetic mutation that rendered these mice sedentary could also have induced obesity (and perhaps diabetes).

Another problem, as we discussed in the last chapter, is that obesity is also associated with poverty, and even extreme poverty, and that should be a compel ing argument against physical inactivity as a cause of the disease. Those who earn their living through manual labor tend to be the less advantaged members of societies in developed nations, and yet they wil have the greatest obesity rates.

A third problem was the observation that exercise accomplishes little in the way of tilting the caloric balance when compared with a very modest restriction of intake—walking a few miles as opposed to eating one less slice of bread—and that increasing activity wil increase appetite. Mayer ignored the comparison of intake and expenditure by focusing on expenditure alone. “For a long period the role of exercise in weight control was disregarded, if not actual y ridiculed,” he wrote in a 1965 New York Times Magazine article. “One reason often advanced for this neglect is that ‘exercise consumes very little energy.’…Somehow the impression was given that any such exercise had to be accomplished in a single uninterrupted session. Actual y, exercise does correspond to a caloric expenditure that can be considerable, and this expenditure wil take place in a day or a decade.” And so the expenditure of calories by exercise, no matter how smal , according to Mayer, would accumulate, leading to long-term weight reduction. This, of course, would be true only if the excess expenditure went unaccompanied by a compensatory increase in appetite and intake.

Mayer acknowledged that exercise could increase food intake, but said it wasn’t “necessarily” the case. This was the heart of Mayer’s hypothesis—a purported loophole in the relationship between appetite and physical activity. “If exercise is decreased below a certain point,” Mayer told the New York Times in 1961, “food intake no longer decreases. In other words, walking one-half hour a day may be equivalent to only four slices of bread, but if you don’t walk the half hour, you stil want to eat the four slices….” Mayer based this conclusion on two of his own studies from the mid-1950s.*78 The first was with laboratory rats and purported to demonstrate that rats that are exercised for one to two hours every day wil actual y eat less than rats that don’t exercise at al . The second was a study of mil workers in West Bengal, India, and stands as a reminder that dreadful science can pass for seminal research in the field of obesity.

Mayer worked with the dietician and chief medical officer of the company that owned the Bengali mil and an accompanying bazaar, and it was these Indian col eagues who assessed the physical activity and diet of the resident workers. These men, as Mayer reported, ranged from “extraordinarily inert”

stal holders “who sat at their shop al day long,” to those engaged in intense physical activity who “shoveled ashes and coal in tending furnaces al day long.”

The evidence reported in Mayer’s paper could have been used to demonstrate any point. The more active workers in the mil , for example, both weighed more and ate more. As for the sedentary workers, the more sedentary they were, the more they ate and the less they weighed. The twenty-two clerks who lived on the premises and sat al day long weighed ten to fifteen pounds less and were reported to have eaten four hundred calories more on average than the twenty-three clerks who had to walk three to six miles to work, or even than those five clerks who walked to work and played soccer every day.

Nonetheless, Mayer claimed that the study confirmed the findings of his rat experiment. He based his conclusion exclusively on the relative girth of thirteen stal holders and eight supervisors. These men weighed, respectively, fifty to sixty pounds and thirty to forty pounds more than the clerks who worked for them, and yet, according to Mayer’s data, consumed the same amount of calories. Mayer implied that they added this extra weight because they were somehow even less active than those employees whose jobs entailed sitting al day, but he had no evidence for it. It’s also possible that their relative wealth introduced other dietary factors that could have explained the dramatic differences in weight. Either way, as John Garrow noted, these findings would never be replicated, which is why such authorities as the Institute of Medicine of the National Academies of Science stil cite Mayer’s study today as the only evidence for the proposition that “too little” exercise can disrupt the mechanisms that normal y regulate food intake.

Mayer’s advocacy of exercise for weight control did not go unchal enged. After his 1965 New York Times Magazine article, entitled “The Best Diet Is Exercise,” physicians working with obese patients wrote to the newspaper saying that Mayer’s faith in exercise was unreasonable and flouted common sense. “As much as Dr. Mayer minimizes the thirst and appetite increases after exercise, my patients al seem to be thirstier after tennis and find it difficult to stick to plain water,” wrote Morton Glenn of New York University Col ege of Medicine; “and who hasn’t heard someone say: ‘This walk al the way home sure gave me an appetite!’ Exercise can and does increase thirst and appetite, in most persons, in most situations, and most people respond to these sensations accordingly!”

Despite these commonsensical objections, Mayer’s hypothesis won out. It helped that Mayer—like Ancel Keys and Dennis Burkitt—perceived the process of convincing the public and the medical-research community to be akin to a crusade. This served to absolve him, apparently, of the obligation to remain strictly accurate about what the research, including his own, had or had not demonstrated. In the popular press, Mayer would unleash his less scientific impulses. He wrote about the “false idea which continues to have broad and pernicious acceptance” that exercise would increase appetite, and he insisted that the “facts overwhelmingly demonstrate” that this was “not necessarily” the case.

As Mayer’s political influence grew through the 1960s, his prominence and his proselytizing contributed to the belief that his hypothesis had both been proven true and was widely accepted. In 1966, when the U.S. Public Health Service advocated increased physical activity and diet as the best ways for us to lose weight, Mayer was the primary author of the report. Three years later, Mayer chaired Richard Nixon’s White House Conference on Food, Nutrition, and Health. “The successful treatment of obesity must involve far reaching changes in life style,” the conference report concluded. “These changes include alterations of dietary patterns and physical activity….” In 1972, Mayer began writing a syndicated newspaper column on nutrition that clearly did not hold to the standards of a serious scientific publication. Sounding suspiciously like a diet doctor sel ing a patent claim, Mayer said that exercise “makes weight melt away faster.” “Contrary to popular belief,” Mayer asserted, “exercise won’t stimulate your appetite.”

The current culture of physical exercise in the United States emerged in the late 1960s, coincident with Mayer’s crusade and accompanied by a media debate about whether exercise is or is not good for us. “While it is general y agreed that exercise programs can improve strength, stamina, coordination and flexibility and provide an overal sense of wel -being, two crucial questions remain,” a 1977 New York Times Magazine article observed: “(1) Does exercise prolong life? and (2) does it give any protection against the modern scourge, heart disease?” A handful of observational studies had linked exercise to greater longevity—the most famous being a study of seventeen thousand Harvard alumni published by Ralph Paffenbarger in 1978—but these didn’t reveal whether this effect was due to the health benefits of exercise or the fact that healthier people are more likely to exercise. Those who exercised regularly also tended to smoke less and pay more attention to their diets.

Nonetheless, the view of exercise as a panacea for excess weight soon became conventional wisdom. “Diligent exercisers tend to lose weight,” was how a Washington Post article on the fitness revolution phrased it in 1980. No source for this claim was deemed necessary. Al doubts about whether the weight-reducing benefits of exercise actual y existed were left behind. In 1983, Jane Brody of the New York Times was counting the numerous ways in which exercise was “the key” to successful weight loss. Exercise, she explained, increases metabolism for hours afterward, which further increases caloric expenditure. It is also “an appetite suppressant, sometimes delaying the return of hunger for hours.” Exercise builds up muscle tissue, Brody said, which in turn burns more calories than fat. And muscle tissue is denser than fat, Brody concluded, “so even if you do not lose any weight, exercise wil make you trimmer.” By the end of the decade, as Newsweek observed, exercise was now considered “essential” to any weight-loss program. In 1989 the New York Times counseled readers that, on those infrequent occasions “when exercise isn’t enough” to induce sufficient weight loss, “you must also make sure you don’t overeat.”

The press may have been convinced, but the scientific evidence never supported Mayer’s hypothesis. In October 1973, when the National Institutes of Health hosted its first conference on obesity, Per Björntorp, a Swedish investigator, reported about his own clinical trials on obesity and exercise. After six months of a thrice-weekly exercise program, his seven obese subjects remained both as heavy and as fat as ever. Four years later, when the NIH again hosted a conference on obesity, the conference report concluded that “the importance of exercise in weight control is less than might be believed, because increases in energy expenditure due to exercise also tend to increase food consumption, and it is not possible to predict whether the increased caloric output wil be outweighed by the greater food intake.” In 1989, when Xavier Pi-Sunyer, director of the Obesity Research Clinic at St. Luke’s