Fats are a group of chemical compounds that contain fatty acids. Energy is stored in your body mostly in the form of fat. There are three main types of fatty acids: saturated, monounsaturated and polyunsaturated. Reducing all types of fat in your diet is best.
Saturated fats are found mostly in foods of animal origin: meat, poultry skin, butter, cheese and partially hydrogenated oils. Saturated fats increase the LDL (bad) cholesterol level in your blood.
Polyunsaturated fats are found in corn, cottonseed, safflower, soybean and sunflower oils. They can reduce LDL cholesterol levels but in excess they may also reduce HDL (good) cholesterol levels.
Monounsaturated fats are the primary fats in olive, peanut, sesame and canola oils. They raise HDL cholesterol as they lower LDL cholesterol, but they should be consumed in moderation.
Trans-fats are found in hydrogenated vegetable oils such as margarines and shortenings, and in many commercially made desserts. Trans-fats raise LDL and lower HDL cholesterol.