oh ok , I was just pulling your leg. 
I know it happens in my office too, but since we have many break rooms and many conference room , so that leftover food from meetings is transfered from conference rooms to break rooms , this way everybody knows that it is free food for everybody to enjoy and does not belong to anybody.
Find a better company to work with , which provides lunch or break rooms for employees, so you do not have to go this kind of trauma ever again. 
Playstation: I am again pulling your leg about working for a better company.