How do they do it?

Tonight we ate at an Italian beer hall and I ended up leaving half of my food on the plate--to the incredible disappointment of our waiter. I have been known to eat a healthy amount, but the food volume here is killing me! How does one consume an antipasti, a primi of pasta, a secondi of protein, then dessert or coffee in one sitting? Granted, I realize the whole meal is intended to take hours, but I still don't get how the Italians can put so much food away, regardless of the time frame. The plate of gnocchi I was served tonight could have fed a large family, but it was intended to only provide the start of the meal for one person. How is it all possible? We spent our meal in awe of the massive appetites of our fellow diners. We are just not worthy..