What is trans fat? A look at different kinds of fats

The FDA is phasing out artificial trans fats from the food supply, but people should limit their intake of saturated fats, too, which can also cause heart disease. There are three main types of fat: unsaturated, saturated and trans fats.

UNSATURATED FAT: These are the good fats, and doctors say they should be the majority of the fat that people eat. For cooking, they usually come in the form of liquid oils, not solid fats. Unsaturated fats are listed on food packages as polyunsaturated fats and monounsaturated fats. Polyunsaturated include soybean oil, corn oil and some fish; monounsaturated fats include olive oil, avocado and many nuts.

SATURATED FAT: These fats are often derived from animals and generally take a more solid form. They raise "bad" cholesterol and can contribute to heart disease. Common sources include high-fat cheeses, high-fat cuts of meat, whole-fat milk and cream, butter, ice cream and palm and coconut oils. The government recommends that saturated fats make up less than 10 percent of daily calories.

TRANS FAT: These are the worst fats, and the FDA is forcing food companies to phase them out. They are made when hydrogen is added to vegetable oil, usually to create a certain consistency or increase shelf life, and they are also called partially hydrogenated oils. Many of them have already been phased out, but foods that are more likely to contain trans fats are fried items, microwave popcorn, frozen pizza, cakes, cookies, pie crusts, stick margarine, ready-to-use frosting and coffee creamers. There are also some naturally occurring trans fats from meat and dairy sources, but the artificial types make up most of what is in the food supply.