I in no way endorse vaping for non smokers but this might be a valid reason for some.
Probably healthier to vape that to be overweight.
From Mt Baker newsletter on 12/19/14
"Two: Lose Weight
Not surprisingly, the second most common New Year's Resolution is the desire to lose weight. While normally this is not something you would consider vaping to be associated with, it actually has the ability to make a dramatic positive impact on attaining your goal. Think about a time when you were dieting and you just craved that cinnamon roll. Did you stick to your guns and deny yourself, or give in? Either way, it was a difficult situation. Now consider this, you have resolved to lose weight this coming year and you start craving cinnamon rolls. Instead of running to the closest bakery, you pull out your e-cig and start vaping the delicious cinnamon roll e-juice, allowing you all of the flavor with none of the calories. You can keep your resolution without sacrificing the taster of your favorite treats!"