The amount of energy needed to maintain essential physiological functions when a person is at complete rest is called
a. anabolism
b. metabolic rate
c. base caloric requirement
d. basal metabolism
The correct answer and explanation is:
The correct answer is d. basal metabolism.
Explanation:
Basal metabolism refers to the minimum amount of energy (calories) that the body requires to maintain essential physiological functions while at complete rest. These vital functions include breathing, circulation, cell production, nutrient processing, and maintaining body temperature. Basal metabolism accounts for the largest portion of a person’s total daily energy expenditure, often about 60-70%.
Here’s a breakdown of the terms in the question:
- a. Anabolism: This is a metabolic process involving the building up of complex molecules from simpler ones, such as protein synthesis. It requires energy but is not the total energy expenditure at rest.
- b. Metabolic rate: This is a general term that describes the rate at which the body uses energy. It can refer to basal metabolic rate (BMR), resting metabolic rate (RMR), or total metabolic rate depending on the context.
- c. Base caloric requirement: This term is not a standard scientific term. It might be used informally to mean the calories needed for basic body functions, but the correct and precise term for energy used at complete rest is “basal metabolism.”
- d. Basal metabolism: This is the precise term for the energy required to sustain vital functions when the body is at complete rest, in a fasting state, and in a thermoneutral environment (neither too hot nor too cold).
Why is Basal Metabolism Important?
Understanding basal metabolism is crucial for many reasons:
- Nutritional Planning: It helps dietitians and healthcare providers estimate how many calories a person needs daily just to maintain basic bodily functions. This information is essential when planning diets for weight maintenance, gain, or loss.
- Medical Assessments: Knowing the basal metabolic rate can help detect metabolic problems such as hypothyroidism or hyperthyroidism, which slow down or speed up metabolism respectively.
- Energy Balance: Basal metabolism forms the baseline calorie usage before physical activities or digestion-related energy expenditures are added.
How is Basal Metabolism Measured?
Basal Metabolic Rate (BMR) is typically measured under strict conditions:
- The person is at complete physical and mental rest.
- The person has fasted for 12 hours (no food or drink except water).
- The measurement is taken in a thermoneutral environment.
- Usually measured early in the morning after a full night’s sleep.
Because direct measurement of BMR can be complex, formulas like the Harris-Benedict or Mifflin-St Jeor equations are often used to estimate it based on age, sex, weight, and height.
In summary, basal metabolism is the fundamental energy expenditure required to sustain life at rest, distinguishing it from other forms of metabolism and energy use.