A lot of people snack while they're trying to quit because of the hand-to-mouth thing. Don't know what to do with yourself. I know I snacked a little, but having sweet juices helped curb that a little. If you gained a bit when you don't have much of an appetite to begin with, then maybe there is more to it than just snacking, though. I know cigarettes have a small dose of MAOIs that vaping lacks but I'm not familiar with it's other side effects besides being mildly anti-depressant.
your husband may want to look into WTA "whole tobacco alkaloid" juices or supplementing with snus.
i dont eat any more than normal to include snacking. ive never been the type to snack. i dont even buy chips or sodas and im not a sweets person. if i ever snack or have something between meals its because im hypoglycemic and have to guzzle a glass of choc milk or eat some crackers with peanut butter. i use my ecig when im missing that hand to mouth thing.
my meds havent changed so if they were gna make me gain weight they would have already done so. the only med that might have an affect is i had a cortizone injection in my t-spine a month ago. but cortizone and steriods only cause weight gain by increasing hunger which hasnt happened and i never gained weight from the injections in the past (ive had 5 sets of them over the past 8yrs).