Body weight‐fat and energy balance

It is characteristic of living organisms that they maintain a specific structure, composition and physical state, although they are continuously losing and gaining the substances of which they are made by exchanges with the outside world. This process is known as homoeostasis, and much of physiology is concerned with it. So well does it work that in the ordinary affairs of life we seldom have to give it much thought. This could at one time have been said of an example of homoeostasis, the maintenance of normal body weight. Recently, however, our community has become more concerned about this.