The major form of fat that is stored in the adipocytes, or fat cells, is triglyceride. One form of adipocyte, white fat, helps in energy metabolism, mechanical softening and heat insulation. Another form called brown fat is mostly available in infants and aids in thermogenesis, or the production of heat.
Adipocytes are usually found beneath the skin and in the abdominal cavity surrounding the organs. Fats are stored more extensively than carbohydrates and provide energy when the carbohydrate supply in the body diminishes. When the body is in need of energy, the triglyceride molecule breaks down into a glycerol molecule and three fatty acid chains. Fats are broken down to facilitate the movement of the small fragments through the cell membrane.