Final answer:
Resting energy expenditure, or BMR, accounts for roughly 70-75% of a person's daily caloric needs. The BMR is influenced by various factors, including muscle mass, and it primarily functions to sustain basic life-sustaining activities of the body.
Step-by-step explanation:
Resting energy expenditure accounts for approximately 70-75% of total daily caloric needs depending on the activity level and occupation of the person. The metabolic rate is crucial as it is the rate at which the body uses food energy to sustain life and engage in various activities.
The basal metabolic rate (BMR) represents the total energy conversion rate of a person at rest and primarily supports the basic functions of the liver, spleen, and brain. Factors such as age, gender, total body weight, and muscle mass influence an individual's BMR. For example, individuals with more muscle mass or athletes tend to have a higher BMR.
Overall, the majority of the calories consumed in a day are dedicated to maintaining these basic vital functions, and only a small percentage is used for work or converted to thermal energy and stored as fat.