They are divided into four main groups consisting of fats, lipids, hormones and steroids. The difference between fats and lipids is that fats are a subset of lipids.
In general, fat performs four functions in the body. It provides energy, essential fatty acids, structural components and regulatory functions.
*One of the major roles of fat is to serve as fuel molecules. The immediate sources of energy for the body are the free fatty acids in the circulation liberated from adipose triglycerides by the enzyme lipase. Triacylglycerol fatty acids provide long-term storage of fuel that can be mobilized during food storage, for growth and during vigorous exercise. They are amore highly concentrated form of metabolic energy than carbohydrates. The main depot is the adipose tissue.
*The body has a remarkable ability to synthesize many compounds and this including excess protein and carbohydrates can be converted to fat.
*Fat in the form of triglycerides, phospholipids, cholesterol and cholesterol esters are important to the structure, composition and permeability of membranes and cell walls. Body fat: can hold organs in place: absorbs shock and: insulates the body against rapid temperature changes or excessive heat loss. Phospholipids are water soluble and may aid in the transport of other fats in and out of cells.
Lipids are present as a bilayer in biological membranes, as a layer on the surface of the skin and in the lung surfactant lipid. Because of their specialized functions, their composition is conservative.
*Regulatory functions. Triglycerides in pure state are relatively tasteless, but they absorb and retain flavors of food. Fats provide texture that enhances palatability and they delay emptying of the stomach and contribute to feeling of satiety.
Dietary fat serves as a carrier for the fat-soluble vitamins A, D, E and K and as an aid to their absorption in the intestine.
Functions of lipids and fats
