I couldn't agree more with eating better and exercising. To the op, maybe the Lap-Band would be more effective means to loosing weight if this is the issue if you can't exercise or control your eating habits.
I don't see how an e-cig is going to help. I use several sweet flavors and they do nothing to curb any desire I have for something sweet. If anything they make me want it more because it's not the same as eating that item. I just don't keep that type of stuff in the house so it's not an issue for me. FWIW, I'm 270lbs, so it's not like I'm some skinny guy telling you this.
Why doesn't your doctor recommend eating properly and exercise instead of e-cigs?