Basal metabolic rate (BMR) is the average daily amount of energy (calories) that is used by a body when it is at rest. Heredity, height, body composition, and age determine a person's basal metabolic rate. It is also known as basal energy expenditure (BEE).

The energy in a person's BMR is used to keep body temperature normal and to power the heartbeat, breathing, and other organ functions. Your BMR uses up about two-thirds of your daily calories.