What are Trans Fats & Why are they Bad?

Trans fats are created by heating liquid oils to very high temperatures (in a process known as hydrogenation). This process is done to create a fat that remains solid at room temperature and that won't go bad as quickly -- useful traits for cooking. The resulting partially hydrogenated fat is the artery clogger. Trans fats are essentially unsaturated fats that have been converted into saturated fats. Because trans fats behave like saturated fats, avoid them. Manufacturers are requred to list trans fats on food labels.

Saturated fat, which raises cholesterol, is found in animal products -- think butter, whole milk, and steak -- and in tropical oils such as palm and coconut. Unsaturated fats, which can lower LDL (bad) cholesterol, are always liquid and found in vegetable oils. They come in two forms: monounsaturated (olive and canola oils) and polyunsaturated (safflower, sunflower, corn, and soybean oils). All fats are calorie dense, so eat even good ones in moderation. We all know that raising your LDL cholersterol causes buildup of plaque in your arteries, which in turn can cause heart disease.

Trans fats, however, deliver a damaging one-two punch: They not only raise your LDL, they also lower your HDL. Trans fats also boost blood levels of C-reactive protein (CRP), a marker for inflammation that has been associated with heart disease.

Food sources: Processed foods like cookies, crackers, potato and tortilla chips, and margarines; fried fast foods.