What you need to do is get that tape measure out, and start measuring that gut. Then you start working out and you start eating properly till that gut gets down close to it was when you were in your 20's. Then you'll find out what your weight should be.
I'm still waiting to hit it big. But there was the moment when I didn't have to work at the restaurant anymore, which is the milestone for every actor. When your job is just to be an actor and not to have to do anything else.
I never like to refer back to anything I've done when I'm working on a character, even if that character has the same occupation.