Metformin is a drug used to treat metabolic syndrome/pre-diabetes. Sometimes psychiatrists prescribe it with a drug known to cause weight gain and sometimes they'll add it to help patients lose weight. A lot of psychiatrists won't use it at all since it's not indicated for that. Studies have shown that it works best with a regimen of regular exercise and sensible diet. Of course so does everything.

Contrave is part Wellbutrin and part a drug called naltrexone. Wellbutrin, you probably know, is an antidepressant. It does lower your appetite and you can lose some weight, but that effect seems to go away pretty fast

Naltrexone is prescribed to help opiate addicts recover. It's an opiate antagonist so if you do go back to using drugs you don't get a high and that should curb your habit.It also seems to help with alcoholism. Some users say it takes away their appetite.

Contrave is supposed to be synergistic so that the drugs work better together than each would individually.

I don't think either Contrave or Metformin are stimulants.