Fatty acids are composed of carbon and hydrogen molecules in a chain-like formation. The numbers of carbon atoms which form the chain define the fatty acid. Those fatty acids containing carbons 18 carbons are known as short-chain fatty acids and those with 18 or more known as long-chain fatty acids. Short-chain fatty acids can actually be converted to long-chain fatty acids in the body, albeit an inefficient process, via enzyme elongation reactions. Fatty acids can be divided into the following categories: saturated fats, monounsaturated fats and polyunsaturated fats.