I have only been
vaping for a week so I can only give you my experience based on that, BUT I have lost two pounds. I think it is like most of what you will read on this forum: it depends on the individual. I know a lot of what I have read from those who have been on here for awhile states that they found flavors problematic at first because after
vaping a flavor like a dessert flavor, for example, they wanted a cigarette because it was like eating. For me, vaping flavors is like a treat, so I don't want to eat something sweet after vaping a sweet flavor and don't want to smoke an analog either. I feel really lucky in this regard. For the most part, nicotine is a stimulant (even though it can CALM your nerves). Most people who quit nicotine altogether will gain 10-15 pounds without changing their eating habits just because of the loss of that stimulant which helps burn calories. Unless you are giving up nicotine, it would make sense that weight gain would be at a minimum but I think you are going to have to play with flavors and find ones that make you feel satified...both from your analogs AND from snacks.
I can say that after just one week, I feel SOOO much better and also tend to be more active, which I am sure doesn't hurt. The fact that I don't feel guilty vaping while taking a walk when I would have felt like I was being counter-productive if I smoked while doing the same activity doesn't hurt either.
Hope this info helps a little. Keep vaping, play with flavors and I'm sure that whatever you are experiencing will level out. =D