Fats are digested and absorbed into the body and excreted through the production of energy, water and carbon dioxide; undigested fats are turned into feces and excreted through the large intestine. Fat is digested in the small intestine to produce fatty acids, glycerol, cholesterol, etc. and bile salts to form mixed microcolloids, which are absorbed into the cells of the mucosal epithelium of the small intestine, released, and enter the lymphatic vessels and the blood. Finally, it mainly enters the bloodstream, lymphatic system, etc. and is transported into the liver, through which it is changed into body fat, to the point where it is utilized to produce energy, carbon dioxide, and water. Water and carbon dioxide are then eliminated from the body by major means such as respiration and urination respectively. Excess fat can be stored and changed into human body fat. If it is not digested and absorbed by the stomach and small intestine, it is changed into feces and pushed into the rectum through the peristalsis of the small and large intestine, etc., and then excreted from the body.