Body fat is a much used but not always well understood physiological expression. Body fat is the stored fat that is a product of the ingestion of dietary fats, as well as any fats resulting from the conversion of carbohydrates and proteins in the body. Body fats are stored as triglycerides. These compounds are formed from three fatty acid molecules, attached to glycerol, a type of sugar. Body fats are stored within specially designed cells known as adipose tissues, which tend to be concentrated around the internal organs, under the skin (subcutaneous fat) in the chest, abdomen, and buttocks in males or in the breasts, abdomen, upper thighs, and hips in females.
Body fat is capable of indefinite storage; if the body does not require the stored energy as contained in the fat cells, it will never degrade or otherwise metabolize. Body fat is an excellent source of energy, as 1 gram of body fat will produce 9 Kcal (calories) of energy; both proteins and carbohydrates are capable of only 4 Kcal per gram. Fat cells that contain body fat are metabolically inert, requiring very little energy for their maintenance, unlike the lean tissue structures of bone, muscle, and the internal organs. To access the stored energy of the adipose tissues, the hormone glucagon regulates the release of triglycerides into the blood for energy production. When released from their adipose cells, the triglycerides are divided into their fatty acid and glycerol components. The fatty acids are reconstituted in the bloodstream as lipoproteins, and they are transported to the various cells as a source of energy. The glycerol is directed to the liver for processing as a carbohydrate source of energy.
The amount of body fat released into the bloodstream as triglycerides is a statistical tool concerning general cardiovascular health; excess quantities of triglycerides are a well-known contributor to arteriosclerosis and other cardiovascular diseases.
It is unhealthy for any human to possess too little or too much body fat. Body fat performs an important role in the insulation of the body from cold, therefore playing an important role in the protection of the internal organs as well as assisting in the general thermoregulatory function of the body. Excess body fat is harmful to health in a number of ways. Excess body fat is a simple drain on the energy resources of the body, in that the organs, respiratory function, and musculoskeletal system are transporting additional mass with every step, placing a strain on the cardiovascular system and all joints. Persons with excess body fat also compromise their balance and coordination skills, as they are maneuvering a body too large for the sensory devices that the body relies on to achieve efficient movement.