In McDonald's and Kentucky Fried Chicken fast food in high levels of compounds have been proven to have a carcinogenic effect. Fast food in the hamburger, French fries, fried chicken, pizza, etc., because of the high fat content, not only will increase body weight, for young people are developing brain will also cause permanent damage. Children who regularly consume foods such as cola, soft drinks, candies, French fries, potato chips and hamburgers are prone to nutrient deficiencies and do not grow. In 2002, the World Health Organization has announced, for a variety of brands of "foreign fast food" in the french fries, pancakes, roast pork and fruit desserts on the brown crunch and a large number of oil fried fried fast food laboratory test showed that some of the propylene toxin content of more than 400 times the standard.