Triglyceride, glycerol and fatty acids, illustration. Triglyceride (left) is an ester that is derived from glycerol (upper right) and three fatty acids (lower right). Triglycerides are the main element of body fat and skin oils in humans. Glycerol is a simple triol, a compound with three 'OH' (alcohol) groups. It has the chemical formula: C3.H8.O3. Fatty acids are long-chains carboxylic acids. These molecular models are colour-coded, with spheres representing atoms of carbon (black), hydrogen (white) and oxygen (red).