A drug that promotes weight loss, lessens the desire to smoke, drink, etc...sounds too good to be true? From what I have heard, all of these issues come back as soon as someone comes off the drug. So either a person is committing to a lifetime of being dependent on this drug, or a person is committing to some period of time of ideal living, followed by a possible time of depression after reverting to the status quo.
Similarly, if a person loses 30 pounds on this drug, then stops using the drug and reverts to normal habits, it will take a while to regain those 30 pounds. And the long term shift of maintaining the new body weight doesn't require any radical changes (unlike losing 30 pounds, which does require sustained radical changes).