I have noticed that when I work in the concession stand at my kids games, I lose my appetite. It is disgusting food though, I doubt your Italian Restaurant is like that. But I think it has to do with being around the food so much, not necessarily the quality of the food. I get tired of the smell, touching it, etc. Maybe you are doing that also?
Generally I have never had trouble eating though.

Of course, I've never worked in the restaurant industry either.