ENERGY REQUIREMENTS OF THE BODY

Combustion(a process of energy release ) in living beings was first described by Lavoisier(1743-1794).This brilliant chemist discovered the true nature of oxygen and how its combination (in the body) with carbon and hydrogen results in formation of CO2 and H2O and production of heat.
In 1842,Liebig announced that the substances burned in the body for energy liberation were carbohydrate,fat and protein.
Energy is needed for maintenance of body tissues and body temperature, for growth and also for physical and mental activity as well as for reproduction. In other words energy is needed for all physiological processes that go on in the body. The body expends energy for:
1.Voluntary actions,such as running, walking, swimming,typing and talking.The energy requirement of different activities has been tabulated .
2. Involuntary actions, such as expansion and contraction of the heart, respiration, and digestion.Involuntary actions include energy needed for body maintenance and is known as the Basal Metabolic Rate or BMR .This energy must be supplied to the body first,because energy required by the heart for its normal functioning or for the constant supply of blood to the brain are vital functions upon which survival of a living being depends.
Basal Metabolism, therefore, represents the irreducible minimum of energy required to keep up the life processes,i.e. for the basic internal functioning of the body.It is usually defined as the amount of energy required by the body