Human energy and the energy balance
Prehistoric peoples likely recognized a correlation between the intake of food and human energy. A person who doesn’t, or can’t, eat reaches a point at which he or she is no longer able to fend for, or even care for, himself. Death becomes inevitable. World history contains dreadful tales of human suﬀering and death during famine or deliberate starvation. In the nineteenth century, chemists studying the composition of
foods and the biological processes of life established three key facts:
The major components of foods are carbon, hydrogen, and oxygen.