Why would short term be a problem? Every other FDA approved drug is short term. ADD medication works until you stop taking it, birth control works until you stop taking it, etc. That's probably a good thing. I don't think I would want a drug that causes permanent weight loss
Well, what if you were taking ADD meds and they stopped working while you were taking them, or a medicine for epilepsy which stopped working while you were taking it? Amphetamine derivatives stop working for most people while they are on them.
So some people lose some weight and then the medicine stops working but then they have hypertension which in some cases doesn't go away. What it comes down to is risk vs. benefit and current meds fail.
Even though in some people methamphetamine and their derivatives cause profound weight loss it's mostly seen in addictive personalities.
BTW, the nicotine weight gain isn't just increased appetite, but an actual alteration of metabolism which will cause people to get fatter if fed the same food. Been done in controlled studies so it's not anecdotal.
But getting back to the hunger issue, many people don't get the message that they are full and continue to eat beyond their physical needs. Unfortunately that seems to happen more with sedate lifestyles which we almost all live. Cubicles aren't conducive to good health or eating habits. That Grail I mentioned suppresses appetite and doesn't fade while the patient is on therapy and also has a metabolic enhancing effect. The ideal drug would make people who overeat and have lower metabolisms like those who can eat and not gain weight.
Going back to the earlier "big pharma owns the FDA", if a drug worked half assed, but caused some weight loss they could buy them and market the med to death and make billions. They don't because they can't and they can't because the FDA won't let them.