Atwater and his colleagues also constructed a giant live-in calorimeter to measure the combustion of food by the human body. This calorimeter was large enough to provide a modest living space for experiments lasting multiple days. Atwater’s system was so effective that it was able to demonstrate with greater than 99 percent accuracy that the energy entering a weight-stable person as food is equal to the energy leaving the body. In other words, in a person neither gaining nor losing weight, the number of calories consumed is equal to the number burned.
