The Skinny On Smoking: Why Nicotine Curbs Appetite : NPR
Very interesting, that link. I know that one of the fears of quitting smoking for a lot of people is the weight gain, but i think a lot of that has to do with replacing smoking with snacking, or gum, or candy, to help curb the cravings. I'm finding less of an urge to snack with vaping.
Drinking water will absolutely help with losing weight.
Nicotine also releases dopamine in the brain, which is the "happy" hormone. A lot of people trying to quit smoking try to get that hit of dopamine from food, like sugar.
Smoking or using nicotine should increase your metabolism, as it's a stimulant. That's one of the features of vaping I'm curious about - I'm using my rising energy levels to up my exercise routine, but I have some concern that it's still risky to use nicotine for a period of time before doing any cardio or lifting, and after - I think it would be as dumb and dangerous as smoking while doing any of that. But, I'm getting additional kicks to my metabolism by vaping, and doing without for an hour or so to work out is a lot less painful than before.
As for people who gain while gaping, I don't know, but I'd love to know why, but we're all different, we all have different bodies, body chemistry, and lifestyle.