Introduction Triacylglycerols, also known as triglycerides, are the simplest lipids formed by fatty acids. It is made up of three fatty acids ester linked to a single glycerol. Most triacylglycerols contain two or three different fatty acids. Triacylglycerols are nonpolar, hydrophobic, and insoluble in water. This is due to the ester linked bond between the polar hydroxyls of glycerol and the polar carboxylates of the fatty acids. Common triacylglycerols are vegetable oils, dairy products, and animal fat.
Functions Triacylglycerols are stored as fat droplets in large amounts in vertebrate fat cells, and in plants as oils in the seeds. Triacylglycerol is a better stored energy source than polysaccharides because oxidation of triacylglycerols produces more than twice as much energy than the oxidation of carbohydrates. In addition, due to triacylglycerol's characteristic of being hydrophobic, it does not require hydration, thus it saves the organism the energy required to carry the extra water. 
Also, triacylglycerol located under the skin can function as insulation, in addition to being an energy source.
- Cox, Michael M. and Nelson, David L. Principles of Biochemistry. 5th ed. New York: W.H. Freeman, 2008. Print.