Total Energy Expenditure or Utilization

 has three components:

 

•BMR: energy expenditure at complete rest and without physical work.

•Physical activity: for mechanical work.

•Specific dynamic action or Thermogenic component: energy expenditure due to the physiological response following the ingestion of food, and exposure to cold or stimulants.

•Resting energy expenditure or basal energy expenditure: The minimum energy needed to maintain basic physiological functions.

•The rate of energy expenditure at rest (kcal/hour) is measured as either the resting metabolic rate (RMR) or the basal metabolic rate (BMR).

•BMR: the minimum level of energy expended by the body to sustain life in the awake state.

–12 to 18 hours after the ingestion of food

–at complete rest, at a comfortable temperature

–restful state of mind

Under these basal conditions the energy output of the body is relatively constant and low.

•BMR and RMR are almost same, except that RMR includes energy required for digestion, absorption, and distribution of ingested food (e.g., determinations are made in a nonfasting state).  They are virtually interchangeable.

•BMR is defined as the number of calories given off by the body per square meter of body surface per hour.

•The average BMR for normal adult males varies from 36 to 41 cal/m2/hr and for normal adult females, from 34 to 36 cal.