It is important to have an empty stomach when having general anesthesia as a person may vomit while going to sleep or waking up, and then inhale stomach contents into the lungs, which can be very dangerous. The hospital will call you the day before the surgery with complete instructions about what time to stop giving your child food and drink. These instructions should be strictly followed. If your child does have something to eat or drink, you should let the nursing staff know on your arrival at the hospital.
Some parents and children, especially teenagers, worry about missing meals on the day of surgery so "stock up" the night before with a large meal. Fatty food, such as pizza, empties slowly from the stomach and after a large fatty meal, the stomach may still have food in it the next morning. Do not over-feed your child or allow them to over-eat the night before surgery and avoid large, fatty meals.