basal metabolism n the turnover of energy in a fasting and resting organism using energy solely to maintain vital cellular activity, respiration, and circulation as measured by the basal metabolic rate
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the minimum amount of energy expended by the body to maintain vital processes, e.g. respiration, circulation, and digestion. It is expressed in terms of heat production per unit of body surface area per day (basal metabolic rate - BMR), and for an average man the BMR is 1.7 Calories (7.115 kilojoules) per day. BMR may be determined by the direct method, in which the subject is placed in a respiratory chamber and the amount of heat evolved is measured, or (more normally) by the indirect method, based on the respiratory quotient. Measurements are best taken during a period of least activity, i.e. during sleep and 12-18 hours after a meal, under controlled temperature conditions. Various factors, such as age, sex, and particularly thyroid activity, influence the value of the BMR.
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the minimal energy expended for the maintenance of respiration, circulation, peristalsis, muscle tonus, body temperature, glandular activity, and the other vegetative functions of the body. The rate of basal metabolism (basal metabolic rate) is measured by means of a calorimeter, in a subject at absolute rest, 14 to 18 hours after eating, and is expressed in calories per hour per square meter of body surface.Medical dictionary. 2011.