Metabolic rate is the rate of metabolism, the amount of energy used by an animal per unit of time. Basal metabolic rate (BMR) is the amount of energy used daily by animals at rest.
| Energy expenditure breakdown | |
|---|---|
| Liver | 27% |
| Brain | 19% |
| Heart | 7% |
| Kidneys | 10% |
| Skeletal muscle | 18% |
| Other organs | 19% |
About 70% of a human's total energy use is due to the basal life processes within the organs of the body (see table). About 20% of one's energy use comes from physical activity and another 10% from the digestion of food after eating.[1]
All of these processes require an intake of oxygen to provide energy for survival, usually from macronutrients like carbohydrates, fats, and proteins. The Krebs cycle produces energy-rich ATP molecules, and gives off carbon dioxide.
- ↑ McArdle, William D. (1986). Exercise physiology (2nd ed.). Philadelphia: Lea & Febigier. ISBN 9780812109917.[page needed]