Feast Your Eyes: Where Calorie Counting Comes From Chart: Wilbur Atwater's Calorie Counts, Circa 1902
Wilbur Olin Atwater's experiments with a "bomb calorimeter" helped develop the system of food energy dieters and food manufacturers rely on today.
In 1902, Wilbur Olin Atwater created this chart to quantify the nutritional content of beef, flour, sugar, and various other foods. Atwater, a scientist working at Wesleyen University in Connecticut, believed that optimal human nutrition would come through the study and quantification of foods, as well as carefully measuring the energy expended during certain activities.
To measure energy in various foods, he burned small amounts of each inside a bomb calorimeter—a lab tool that surrounds a food-filled capsule with water. The heat given off determines the energy contained in beef or flour; one calorie raises the temperature of one kilogram of water one degree Celsius. Food calories are actually kilocalories and Atwater found that fat had 9 kilocalories per gram, carbohydrates contained 4 kilocalories per gram, and protein weighed in at 3 kilocalories per gram.
This system underlies the current nutrition labeling and calorie counting on menus, but rather than burning Twinkies, Honey Nut Cheerios, or Granny Smith apple slices inside calorimeters, food manufacturers and restaurants rely on the precise estimates he developed—now called Atwater units—to determine the calorie value of foods, which have been standardized in these U.S. Department of Agriculture tables.
Atwater's work guides our thinking on nutrition programs and his system for quantifying food underlies an approach that, for better or worse, determines the value of foods with scientific-sounding numbers.
Chart from: Principles of nutrition and nutritive value of food, via University of North Texas Libraries Government Documents Department, Denton, Texas. Thanks to Jessica Mudry, the author of Measured Meals, for background and assistance.