The amount of energy needed by the body for maintenance of life when the person is at digestive, physical, and emotional rest.
The amount of energy required to maintain cellular activity and vital functions of respiration and circulation in a resting, fasting body.
The minimum amount of energy needed to keep the body functioning and the temperature standard when at rest.
The minimum activity of metabolic processes occurring in the body. With reference to energy, it is the least amount of energy used by the body to sustain itself. When measured, the individual is at rest (not asleep), in a comfortable environment (neither shivering nor sweating), free of emotional, mental, and physical stress, and at sexual repose. The basal metabolic rate can be measured as the heat produced or as the oxygen consumed by the body under these conditions. Oxygen consumption is considered the indirect measure of basal metabolism under the assumption that energy consuming reactions which produce heat also use oxygen. Other indirect measures have been devised that relate to either heat production or oxygen use. Table 14 lists some of these methods.
Basic rate of energy flow needed to maintain the body.
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.
The lowest level of energy expenditure required to sustain essential bodily functions when the body is entirely at rest in a warm room, typically occurring 12 to 18 hours after food intake.