My dad quit cold turkey over ten years ago after smoking for 57 years, starting at the age of 8, because cigarettes were easier to get than food, taking the hunger away... He hasn't gained weight since then, nor being angrier than before. I guess one good reason for both is, that he has routines such as gym and volley ball twice a week, steady meal times and no snacks in between, social life, light gardening, shopping with mom etc.
My wife did the same thing about six years ago. Her substitute is knitting. Hint: Bamboo sticks don't make noise!