Provide stored energy for the body (9 kilocalories/gram), functions as structural
components of cells and also as signalling molecules for proper cellular
communication. Lipids provide insulation to vital organs and works to maintain
body temperature.
Lipids are also a family of molecules composed of carbon,
hydrogen, and oxygen, but unlike carbohydrates, they are insoluble in water.
Lipids are found predominantly in butter, oils, meats, dairy products, nuts,
and seeds, and in many processed foods. The three main types of lipids are
triglycerides (triacylglycerols), phospholipids, and sterols.
The main job of triacylglycerols is to provide or store energy. Lipids provide more energy per gram than carbohydrates (9 kilocalories per gram of lipids versus 4 kilocalories per gram of carbohydrates). In addition to energy storage, lipids serve as a major component of cell membranes, surround and protect organs (in fat-storing tissues), provide insulation to aid in temperature regulation.
Phospholipds and sterols have a somewhat different chemical structure and are used to regulate many other functions in the body.
