Final answer:
The amount of energy the body needs to maintain life while at rest is called basal metabolic rate (BMR). Factors influencing BMR include age, gender, total body weight, and muscle mass.
Step-by-step explanation:
The amount of energy the body needs to maintain life while at digestive, physical, and emotional rest is called the basal metabolic rate (BMR). BMR is the rate at which the body uses food energy to sustain life and to perform basic functions like breathing, digestion, and maintaining body temperature.
During rest, about 75% of the calories burned in a day go into these basic functions. The BMR is influenced by factors such as age, gender, total body weight, and amount of muscle mass. Athletes tend to have a higher BMR due to their increased muscle mass.
Overall, energy is consumed and utilized by various systems in the body, with the largest fraction going to the liver and spleen, followed by the brain. During vigorous exercise, the energy consumption of the skeletal muscles and heart increases significantly.