Final answer:
The Basal Metabolic Rate (BMR) is the measure of energy needed to maintain the basic bodily functions at rest without food, and it makes up approximately 70% of the daily energy expenditure.
Step-by-step explanation:
The measure of the energy needed to maintain life while at rest and without food is known as the Basal Metabolic Rate (BMR). This rate defines the amount of energy expended daily by the human body when at complete rest, in a temperate environment, while in the postabsorptive state - meaning after the body has finished digesting food.
The BMR accounts for about 70% of all daily energy expenditure and is essential for maintaining the basic functions of organs in the body. As a person's activity level or lean body mass increases, so does the BMR. Conversely, with age, as lean muscle mass tends to decrease, BMR also declines.