My hubby was a tobacco user for 22 years. His dad thought it was so funny when he tried his dip. The only reason he quit is because he bought a on/of motorcycle and I told him he had to get life insurance. It would have cost him 2 1/2 times more if he continued to chew! Thankfully, he hates to pay more for anything and after a VERY IRRITABLE week, he quit, he didn't gain weight because he was riding a lot. He did switch to a non nicotine chew for a year and this past January he quit that. His cousin just quit smoking and went from weighing 185 pounds to 225.
Most folks I know who have stopped smoking have gained weight - but I think it has more to do with not breaking the hand to mouth habit than anything else.
I rarely bother with cigarettes if I'm curled up with a good book - but can wipe out a can of peanuts or a bag of chips without even realizing it.
Of course I can get away with that - I'm 5'10" and 115 pounds :)