Energy and Calories Energy is a key component within the body.
All carbon containing compounds have a certain amount of energy.
Most energy measurements are currently reported as calories or kilocalories. Another measurement, the joule or kilojoule is used primarily for research purposes, and will not likely be used extensively in the consumer market for several years. One pound of body fat contains about 3,500 calories. This represents the amount of energy expended by a person at rest and under thermal neutrality. REE is closely related to lean body mass.