Short for Trans Fatty Acid: An artery-clogging fat that is formed when vegetable oils are hardened into margarine or shortening. Many food companies use trans fat instead of oil because it reduces cost, extends storage life, and can improve flavor and texture. Food companies are also not required to list trans fat on nutrition labels (until 2006) even though trans fat is worse than saturated fat.
While some foods like bakery items and fried foods are obvious sources of trans fat, other processed foods, such as cereals and waffles, can also contain trans fat. One tip to determine the amount of trans fat in a food is to read the ingredient label and look for shortening, hydrogenated or partially hydrogenated oil. The higher up on the list these ingredients appear, the more trans fat.