A 12" cheese pizza has about 2000 calories.
A 6' tall 160 lb man who does vigorous exercise 5+ times a week needs 2500-3000 calories per day to maintain weight.
So if you're still hungry it's because you didn't eat much else all day. Or you're training like an Olympian. Or you're on your way to getting fat. Or European pizzas are low in calories.