Heat can't provide energy, and the dissipation of heat is to keep the body temperature constant, and it also needs to keep people's body. Without food in the stomach, it can't provide the energy they need. The human body needs energy to keep exercise, and the maintenance of heat is to better maintain the stability of the body, while the food in the stomach is consumed, providing the required nutrients to all parts of the body and providing the amount of activities needed by all parts. The food is chewed and broken into small pieces first. Then enter the oral cavity for decomposition, where starch is decomposed into maltose, then enter the throat and esophagus for simple digestion, then slowly enter the small intestine for digestion, draw some nutrients, then enter the large intestine to decompose and absorb all nutrients, and then remove the residues without any nutrients from the body.

In this process, food provides the necessary energy, provides sufficient power for activities and plays an important role in the operation of various organs.

Therefore, when people feel hungry, it is because there is no food in the stomach, and there is no substance that can provide energy. Heat is to maintain the basic metabolism, as well as the heat needed for exercise and physical growth.