We are generally not that fit, but nowdays not many people smoke anymore due even to the cigs' cost compared to tips (nobody get a jobs before 30 :P). And then sure, we're not that used to drink colas and such things.
I'm strange as Italian, because I don't like pasta and I like eating pizza just once a month: anyhow it depends on what you put on pizzas. If it's a margherita, it's just tomato sauce and mozzarella on something like bread. If you start putting on it tons of fried potatoes, wurstels, sausages, half a kilo of mayonnaise, pork ribs, half beef and you drink 4 beers, then yes: you'd be better eat it even less than once an year.
To improve life quality I'd go swimming. It's doesn't make you lose kilos, but it does fit you: you move every part of your body in an ambient with low gravity (and it's a benediction for your back), makes you learn do breath the right way, and makes you relax as hell (depending on the style, ofc).