The mice stores part of the energy from food and utilize the rest in their daily life activities. Some of the energy is stored in the form of fat for the mice have a better control of the exchanges of temperature with the environment, other part of this energy is used to make the systems in the mice body work (cells, tissues, and all the structures of the mice body). The energy from food is in the form of macromolecules that are cleaved in smaller molecules and nutrients that will be used for the process of making all components of the body works. Even the small amount of energy that is stored needs to be comcompartimentalized, and for that the mice use the energy "to spend". To the living organisms food energy is a essential need, because without disponible energy the organism can not work properly.