basal metabolism [Gk, basis + metabole, change] , the amount of energy needed to maintain essential body functions, such as respiration, circulation, temperature, peristalsis, and muscle tone. Basal metabolism is measured when the subject is awake and at complete rest, has not eaten for 14 to 18 hours, and is in a comfortable, warm environment. It is expressed as a basal metabolic rate, according to calories per hour per square meter of body surface. See also Calorie.
