Any way you look at it, you’re going to gain weight when you quit smoking...I am glad I quit but I get more tired running and have gained 15 lbs. my daughter in law also quit June 22nd, and she is super skinny at 27 years old, and even she gained 15 lbs. I run 2 or 3 miles every day ... and I’m not eating any more than normally? So why the weight gain? I’m 5’ 4” and at 149 from 130 lbs...it’s so so uncomfortable @# actually I’ve almost gained 20 lbs in 100 days!