> A drug that promotes weight loss, lessens the desire to smoke, drink, etc...sounds too good to be true?

It does sound too good to be true. However, it's possible that the drug is working on all of these through the same mechanism: by altering the brain's reward system.

If that's true, the drug doesn't make you not want to eat, it makes you not want stuff, in general. That could potentially suppress a wide array of addictive behaviors. I also wonder if that suppression might look a lot like clinical depression, though.