A triglyceride molecule is made of 1 glycerol molecule bonded to 3 fatty acid molecules. The fatty acids are usually quite large, consisting of chains of carbon atoms that can be up to 16 carbon atoms long. The fatty acids store the energy that is contained in a fat molecule. Triglycerides serve as energy storage molecules or as heat insulators in animals. One triglyceride is shown below, where each fatty acid it contains is only 4 carbons long.