Fried foods are often full of fat and may fill you up with unneeded and possibly dangerous types of it. When you order or are buying prepared foods, look for food that is baked instead. Generally you should avoid food that has been fried, unless you know the kind of oil that is being used.
When frying, it is best to use olive or peanut oils because they do not so easily break down. Olive oil also has antioxidant qualities which may reduce the risk of diseases such as cancer. Olive oil can be reused many (up to 40) times, so although it is a little more expensive it turns out to be cheaper in the long run.
It is best not to fry with polyunsaturated oils such as corn, safflower or sunflower oil. If you do, throw any excess oil away as reheating these oils can form some nasty chemical compounds. If vegetable oils are cooked at high temperatures in the frying pan or deep fryer, oxidation occurs rapidly: this is the main argument against fried foods. Slow oxidation underlies the rancidity of fat and rancid fats may increase your cancer risk.