Final answer:
The metabolic rate is the amount of energy consumed minus the amount of energy expended by the body. It is measured as the basal metabolic rate (BMR). About 70% of daily energy expenditure comes from the basic functions of organs, 20% from physical activity, and 10% for body temperature control.
Step-by-step explanation:
The metabolic rate is the amount of energy consumed minus the amount of energy expended by the body. The basal metabolic rate (BMR) describes the amount of daily energy expended by humans at rest, in a neutrally temperate environment, while in the postabsorptive state. It measures how much energy the body needs for normal, basic, daily activity.
About 70 percent of all daily energy expenditure comes from the basic functions of the organs in the body. Another 20 percent comes from physical activity, and the remaining 10 percent is necessary for body thermoregulation or temperature control. This rate will be higher if a person is more active or has more lean body mass.
As you age, the BMR generally decreases as the percentage of less lean muscle mass decreases.