Fats are eliminated from the body through a series of complex biochemical reactions that finally produce carbon dioxide and water. Carbon dioxide is excreted through respiration, while water is excreted in the form of urine and sweat. It is not broken down and excreted by breathing in the traditional sense. Fat in the broad sense includes triglycerides, cholesterol and phospholipids. Fats in the narrower sense are triglycerides, which are composed of glycerol and fatty acids. Fat is widely found in the subcutaneous tissues and around the abdominal organs of the body, where it serves to store energy, maintain body temperature, and cushion internal organs from impact forces. The breakdown and metabolism of fat is accomplished through a series of complex biochemical reactions. Body fat is first broken down by lipase into glycerol and fatty acids. Glycerol is metabolized by the liver and becomes glucose, which is absorbed and utilized by the body. Fatty acids pass through a series of biochemical reactions such as dehydrogenation and oxidation, and finally produce water and carbon dioxide, which are excreted from the body. The specific metabolic process of fat is complex, generally in the state of hunger and exercise, decomposition and consumption, and not by the traditional sense of respiration can be broken down and excreted.