ARS nutritionists find out how many calories we burn when performing various tasks by placing an individual inside a specialized laboratory called a room calorimeter. In Beltsville, a volunteer inside the 'box' performs various tasks and functions, from aerobic exercise to sleeping, and energy expended is carefully monitored. In the direct calorimeter, heat expenditures are measured; in the indirect calorimeter, energy expenditures are calculated from measurements of oxygen consumption and carbon dioxide production. The two methods can be checked against each other to make sure results are accurate.

Updated 7/15/03