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Main Functions of Lipids

Lipids are molecules that occur naturally and include fats, oils, phospholipids and steroids, according to biology experts at Indiana University-Purdue University Indianapolis (IUPUI). Lipids are essential to the human body and have several key functions.

  1. Energy Storage

    • Biologists at Western Kentucky University (WKU) report that a main function of lipids is energy storage. Because lipids pack in more energy--in the form of calories--than protein or carbohydrates, they are an ideal way to store energy. IUPUI experts note that fats can store twice as much energy as glucose, and that fat has twice as many energy-rich carbon-hydrogen bonds as glucose. The human body produces nine calories when burning a gram of fat; a gram of glucose only yields four calories of energy when burned.

    Foundation of Cell Membranes

    • Lipids are a major building block of cell walls, according to WKU experts. IUPUI biologists report that lipids form the membrane of every living cell. According to the American Oil Chemists Society's Lipid Library, the lipids that form the structural membranes of cells--phospholipids--come in many different subtypes, each of which occurs in specific types of cells or has specific duties. For example, a complex lipid called phosphoidylcholine occurs in most animal cells and plays an important role in the making of certain cell proteins in blood; it is also a significant part of the cell wall in most plants.

    Cell Signaling

    • American Oil Chemists Society experts report that certain types of lipids--such as phospholipids--perform an important function in the body by carrying messages between cells. AOCS notes that platelet-activating factor, an important lipid that causes blood platelets to stick together, also plays a critical role in inflammation and helps the body produce an immune response to invaders. Certain types of lipids also form a protective layer around nerve endings that also helps connect nerve impulses, according to WKU biologists.

    Hormones

    • Experts at Western Kentucky University note that lipids are the foundation of hormones. One particular lipid--cholesterol--forms the basis of all sex hormones in the body, including testosterone, estrogen and progesterone, according to IUPUI biologists. Lipids in the form of fatty acids help regulate certain body processes, such as metabolism and immune function. WKU experts cite hydrocortisone--an anti-inflammatory steroid hormone created by the adrenal gland--as another example of hormones stemming from lipids.

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