My DH gained a stone when he gave up (40+ a day for 30 years.) But the reason he did so was that he replaced fags for Cadbury's Chocolate fingers.
Lots of people start exercising instead of smoking and end up much lighter (you'll be fitter anyway with the not smoking).
One thing that I know helps some people is every time they want a fag, have a drink of water. This stops any urge to eat instead.
Good luck, you are doing the right thing.
I quit smocking and turned to cross stitch a few years ago btw, have to have something to do with my hands being a non-smoker