Good Calories, Bad Calories

The belief in physical activity as a method of weight control is relatively new, however, and it has long been contradicted by the evidence. When Russell Wilder of the Mayo Clinic lectured on obesity in 1932, he noted that his patients tended to lose more weight with bed rest, “while unusually strenuous physical exercise slows the rate of loss.” “The patient reasons quite correctly,” Wilder said, “that the more exercise he takes the more fat should be burned and that loss of weight should be in proportion, and he is discouraged to find that the scales reveal no progress.”

Until the 1960s, clinical investigators routinely pointed out that moderate exercise would lead only to insignificant increases in energy expenditure, and these could be easily matched by slight and comparatively effortless changes in diet. A 250-pound man will expend three extra calories climbing a flight of stairs, as Louis Newburgh of the University of Michigan calculated in 1942, and this in turn is the equivalent of depriving himself of one-fourth of a teaspoon of sugar or a tenth of an ounce of butter. “He will have to climb twenty flights of stairs to rid himself of the energy contained in one slice of bread!” Newburgh observed.

Though more strenuous exercise would burn more calories, it would also lead to a significant increase in appetite. This is the implication of the phrase “working up an appetite.” “Vigorous muscle exercise usually results in immediate demand for a large meal,” noted the Northwestern University endocrinologist Hugo Rony in 1940. “Consistently high or low energy expenditures result in consistently high or low levels of appetite. Thus men doing heavy physical work spontaneously eat more than men engaged in sedentary occupations. Statistics show that the average daily caloric intake of lumberjacks is more than 5,000 calories while that of tailors is only about 2,500 calories. Persons who change their occupation from light to heavy work or vice versa soon develop corresponding changes in their appetite.”^*77 If a tailor became a lumberjack and, by doing so, took to eating like one, there was little reason to think that the same wouldn’t happen, albeit on a lesser scale, to an obese tailor who chose to work out like a lumberjack for an hour a day. In 1960, when the epidemiologist Alvan Feinstein examined the efficacy of various obesity treatments in a lengthy review in the Journal of Chronic Diseases, he dismissed exercise in a single paragraph. “There has been ample demonstration that exercise is an ineffective method of increasing energy output,” Feinstein noted, “since it takes far too much activity to burn up enough calories for a significant weight loss. In addition, physical exertion may evoke a desire for food so that the subsequent intake of calories may exceed what was lost during the exercise.”

By this time, though, exercise had a profoundly influential proponent: the Harvard nutritionist Jean Mayer, who would almost single-handedly overturn a century of clinical evidence and anecdotal experience. In the 1950s, when Mayer established himself as the leading authority on obesity in the United States, he did so based more on the romance of his background than his expertise as a clinical scientist: he was the son of the famous French physiologist Andre Mayer, and he had fought in the French resistance during World War II.

Mayer represented a new breed of obesity authority, of a kind that would now come to dominate the field. His predecessors—among them Louis Newburgh, Hugo Rony, Hilde Bruch, Frank Evans, Julius Bauer, and Russell Wilder—had all been physicians who worked closely with obese patients. Collectively, they had treated thousands of them. Their views on the cause of obesity differed, often radically, but their firsthand experience was unquestionable. Mayer was not a clinician. His training was in physiological chemistry; he had obtained a doctorate at Yale on the interrelationship of vitamins A and C in rats. In the ensuing decades, he would publish hundreds of papers on different aspects of nutrition, including obesity, but he never treated obese patients, so his hypotheses were less fettered by any anecdotal or real-life experience.

As early as 1953, after just two years of research on genetically obese mice, Mayer was extolling the virtues of exercise for weight control. By the end of the decade, he was getting credit from the New York Times for having “debunked” the “popular theories,” argued by clinicians and their obese patients, that exercise had little influence on weight. Mayer knew that the obese often eat no more than the lean, and often even less. This seemed to exclude overeating, which meant the obese had to be less physically active. Otherwise, how could they have achieved positive energy balance and become obese? Mayer himself first reported this phenomenon in a strain of laboratory mice that were prone to both obesity and diabetes. They ate little more than their lean littermates, he noted, but their activity was “almost nil” this sedentary behavior could explain their propensity to grow fat.

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? (Recall 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 Hillel Schwartz, such enormous meals were also the norm: “The 75-cent special at Fred Harvey restaurants in the late 1870s included tomato puree, 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 follow….” 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 smaller.”

Having concluded that caloric intake had actually fallen 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 well 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 billions annually on cars, but is unwilling to include a swimming pool and tennis courts in the plans of every high school.”