I wrote a
blog post about sweet juices that other might find interesting. For those who are busy, the executive summary is that quite a few studies indicate that experiencing sweet flavors without corresponding calories adversely affects food choice and for most people cause weight gain. Though these studies never tested vaping per se, they did show that even diet soda causes weight gain due to this mechanism.
I'm not disputing that some people lose weight while vaping sweet e-juice. Nicotine itself is an appetite suppressant and a lot of people dramatically increase nicotine intake when they switch to vaping. Furthermore, things like drinking additional water, etc. can also affect appetite.
Another thing to consider is that if switching to vaping improves lung function, it could predispose higher levels of exercise than would otherwise be undertaken, and thus compensate for any increased appetite.
Even so, by and large, based upon the science that is out there on the correlation between non-caloric sweet tastes and weight gain, I argue in favor of non-sweet e-juice. However, because of all the other variables, my opinion is also "Do whatever works for you," because there are too many variables.
As for me, it is really hard to say. My weight goes up, my weight goes down. It seems (within its monthly range) to have remained steady. What really has helped my weight though was switching to something called paleo diet in which grains, starchy roots, dairy and legumes are removed altogether. My weight decreased, my BP went down, my VLDL cholesterol went down dramatically, etc.