The Energy Metabolism Laboratory at CNRC

A science-based definition of human energy requirements is crucial in order to set policy guidelines, control and prevent under-nutrition due to insufficient intake of food energy, and help understand factors leading to excessive energy intake.

The faculty and staff of the Energy Metabolism Labora-tory at the Children’s Nutrition Research Center (CNRC) have become leaders in research to determine human energy requirements. The state-of-the-art facility at CNRC can determine the actual energy requirements of healthy individuals across the lifespan from birth to adulthood. The laboratory is equipped with four room respiration calorimeters for adults and older children, as well as a smaller chamber for infants. The room calorimeters are furnished like “a home away from home” with televisions, telephones, com-puters, internet access and exercise equipment. Using the calorimeters, researchers mea-sure the volunteers’ 24-hour basal meta-bolic rate (BMR) and total energy expenditure. An additional measurement often used with calorimetry is the doubly labeled water method that measures free-living total energy expen-diture. This method uses two stable, non-radioactive isotopes to track the end-products of metabolism, water and carbon dioxide. This method requires only that study volunteers drink a small amount of stable-isotope labeled water and collect a sample of their saliva or urine each day for about a week. Doubly labeled water, together with calorimetry, have been used to define the energy requirements of infants, children, adolescents, and women.

Since the energy metabolism laboratory was established in 1990, more than 2000 partici-pants have been residents of the respiration calorimeter room. These volunteers have contributed substantially to the scientific base of human energy requirements. Volunteers are always needed. See the Volunteer section above.