Accounting for Calories

Dieting culture of the 1920s also affected fashion, as in this image of a flapper. By Arthur Ignatius Keller. LC-USZ62-66253.

The long life of the calorie began not in the dieter’s mirror but in 19th-century laboratories and factories. The calorie became indispensable in the study of heat and energy in machines—especially steam engines—and later in human machines as part of food and metabolic studies. So how did the calorie escape from the lab and the factory to become an enduring feature of dieting culture?

During the 1860s scientists began to investigate systematically the chemical composition of foods. They were particularly interested in measuring the energy (heat) value of foods, at first for livestock and later for humans. Knowledge about the heat value of foods, however, was incomplete without answers about how the body used that energy. In the 1880s chemist Wilbur Olin Atwater wanted to know how many calories and grams of nutrients bricklayers required in order to perform their work—information of particular interest to industrial managers. Brickyard managers and proprietors used such studies to learn which diets would promote the greatest production of brick per man at the least cost to the employer.

Though Atwater promoted his own work, the calorie never reached a wide audience. So while ordinary Americans might have read or heard of the word calorie by World War I, many were uncertain of its meaning. But by the end of World War I the Food Administration had turned calorie into a familiar word. The organization published pamphlets and posters encouraging Americans to ration foods shipped off to allied countries, particularly meat, wheat, and sugar. A typical poster in 1918 told Americans that “Food Will Win the War . . . Waste Nothing.” The agency also instructed Americans that they could ration food and still obtain enough calories. To consume more calories than recommended by the Food Administration’s nutrition experts for one’s respective age, sex, and activity level meant undermining both the war effort and physiological efficiency. In New York City, restaurants eager to brandish their patriotism even featured calorie counts on their menus, next to entrée descriptions and prices.

But when war and rationing ended, the calorie stayed on. Until the beginning of the 20th century Americans associated plumpness with beauty and wealth. Thinness implied illness or poverty. Following World War I a sea change in fashion encouraged women to take thyroid extracts, exercise, and buy rolling pins that promised to “roll off the fat.” And when stronger weight loss measures were called for, calorie counting promised a failure-proof, “scientific” approach to weight loss.

By the 1920s a flat-chested, narrow-hipped, long-legged figure epitomized feminine beauty among the fashion-conscious set. Changes in women’s clothing and fashion complemented the shift in the ideal female body. Fashion became an even mightier force in the 1920s as images of the latest styles and featherweight models—real or illustrated—reached consumers via national advertisements, motion pictures, department-store displays, and traveling fashion shows.

The new thin body signified wealth and leisure, inspiring the affluent and aspirational classes to diet. If Atwater introduced the calorie to American nutrition science, doctor Lulu Hunt Peters was the self-proclaimed “popularizer” of calories. Her personal struggles with weight and her own relative success with counting calories convinced her that managing calorie consumption was the answer to weight control. By her own account Peters weighed 220 pounds at her heaviest, then lost 70 pounds through calorie restriction.

From 1918 until her death Peters promoted calorie counting for weight loss through her syndicated column and diet guides. But while Atwater proposed counting calories to achieve physiological efficiency and equilibrium, Peters did so primarily as a tool to manipulate one’s weight for aesthetic ends. She lectured in Diet and Health (the book for which she is remembered), “You should know and also use the word calorie as frequently, or more frequently, than you use the words foot, yard, quart, gallon, and so forth, as measures of length and liquids. Hereafter you are going to eat calories of food. Instead of saying one slice of bread, or a piece of pie, you will say 100 calories of bread, 350 calories of pie.”

Diet and Health sold like calorie-laden hotcakes. In 1922 alone the 105-page book went through 9 printings and topped the New York Tribune’s list of best-selling nonfiction books. By 1930, the year Peters died, the word calorie seemed to roll off people’s tongues, and even some schoolchildren were fluent in calorie counting. In 1927 one home economist observed that “in this country the calorie is a familiar word in the vocabulary of practically every adult, and anyone who doubts the possibility of popularizing it should observe a group of 10-year-old children counting their calories.”

Peters’ program of calorie counting made dieting seem more scientific and failure-proof. To be able to quantify and manipulate food intake gave dieters a newfound feeling of control over the size and shape of their bodies. Not everyone embraced the new dieting culture of the 1920s, but these voices of opposition had little effect on the fledgling cult of thinness. The early 20th-century social forces that enabled the calorie’s transfer from nutrition laboratory to factory to everyday dieting continued through the rest of the century and into the 21st. When Lulu Hunt Peters and other experts seized upon knowledge of the calorie as central to weight loss, the calorie ceased being a relatively obscure term denoting heat value. It had metamorphosed into a body-shaping tool central to dieting.

Chin Jou is a Visiting Scholar at the American Academy of Arts and Sciences. Michal Meyer is editor in chief of Chemical Heritage magazine.

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