Fats are first broken down into glycerol and fatty acids, then enter cellular metabolism and are converted into water and carbon dioxide to be excreted from the body. When the body needs energy, the sugars, fats and proteins in our body are mobilized to provide the body with enough calories. Fats first need to be broken down into glycerol and fatty acids before they can be oxidized by the body’s cellular organelles and thus participate in the supply of energy. Fatty acids are categorized into saturated and unsaturated fatty acids, and glycerol is relatively simple in composition. Many enzymes are required in the catabolism of fats. The body has problems mobilizing and consuming fat if it lacks the enzymes needed for fat breakdown. When the body needs calories, fat will be mobilized, and through the participation of various enzymes and a series of biochemical reactions, it will eventually be converted into water and carbon dioxide, and a large amount of calories will be released. One of the best ways to get fat out of the body is to exercise.