Is it normal to eat a whole pizza?
Depends.It depends
It can be normal to eat a whole pizza, especially if it’s small or you’re especially hungry. A large pizza is a lot for one person, but having one now and then isn’t automatically a problem.
It depends on the size of the pizza, how hungry you are, and whether this is an occasional thing or your usual routine. A personal pizza is designed for one; finishing a large one solo is less typical, but plenty of people have done it after a hungry day or a very good pizza.
You don’t need to feel guilty about one meal. If you often feel unable to stop eating, or it’s upsetting you, that pattern may be worth paying attention to—but eating a whole pizza once in a while is just eating a whole pizza.