Basal metabolic rate (BMR), also called the resting metabolic rate, is the amount of energy needed to support the body's most basic functions when at rest in a neutral, or non-stressful, environment. The BMR is the number of calories a specific human needs per day to stay alive. BMR can be responsible for 70% of the calories burned per day.
The body's most basic functions are those that are immediately necessary for a person to stay alive. These functions include pumping blood, breathing and producing heat. Nonessential functions, such as digestion and standing are not included in this calculation.
The BMR was originally created as a tool for measuring the thyroid status of humans by comparing the metabolic rate of animals to that of humans. Today, the BMR is used as a measure of an individual's metabolism, which changes with age, weight, height, and a variety of medical conditions. A person's exercise habits may affect their BMR.
Both basal metabolic rate and resting metabolic rate are usually expressed in terms of daily rates of energy expenditure. The early work of the scientists J. Arthur Harris and Francis G. Benedict showed that average values could be derived using body surface area (calculated from height and weight), age, and gender along with the oxygen and carbon dioxide measures taken from calorimetry. Studies also showed that by eliminating the gender differences that occur with the accumulation of adipose tissue by expressing metabolic rate per unit of "fat-free" or lean body weight, the values between genders for basal metabolism are essentially the same. Today there are less time intensive tests that are often used in place of the BMR test.
BMR calculations are increasingly being used by the public to formulate weight loss plans that proponents claim can be tailored to the individual needs of the individual.
Today, the BMR is under preliminary investigation to estimate everything from reproductive success to diabetes risk. The results of such inquires remain unknown.
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