Why can a person live without water for a week, without food for a month, and without air for a minute?

1) From food, a person receives energy and substances for life, water is necessary to maintain the constancy of the internal environment and for the course of all reactions, and oxygen for breathing.

2) In extreme conditions, a person can do without food and water. Water will enter the cells from fat (“metabolic water”), as well as from other cells and tissues in which it is currently needed less. Energy will come first from glycogen (in the liver, muscles, kidneys and brain), and then, again, due to the breakdown of fats (in the worst case, muscles will be broken down).

3) Oxygen cannot be obtained from the body, because it is not stored, but instantly spent and re-supplied. Without oxygen, hypoxia will quickly set in, first of all, the brain will suffer, and after a few minutes the person will simply suffocate.