I have seen some larger gentlemen sporting those expanding waistband trousers. They look like something kids wear.
thats why i said, the likely risks are of being a social outcast.
oh i forgot, the best of both worlds, there are drawstring pants as well, now mostly these are casual linen types, and the drawstring is in place of a belt but the waistband is structured so the drawstring does not give you substantially more room.
you can always do what Joey did for thanksgiving in friends. :D