On the basis of what data is the amount of food necessary for the body determined?

The amount of food that a person needs per day is determined by his needs. Everything that a person does: breathing, movement, providing all the functions of the body, is accompanied by the consumption of energy. This energy is formed from nutrients that enter the body. All food is digested, broken down to proteins, fats and carbohydrates, and then, each of the molecules is broken down to carbon dioxide and water, and a certain amount of energy is released. All this energy goes to meet the needs of the body. The excess can accumulate in the form of storage fats.