"i dropped 35 pounds on this medication in 6 months without exercising. i also took up smoking cigarettes and heavy drinking to counteract the jitters that can leave you unable to sleep. (not a good combination for your body.) you have to literally force yourself to eat.  your body will build up a tolerance to it, even at increased dosages, and eventually you will have to get off of it.  so if you have not established a healthy change of lifestyle (which was my unattained goal to begin with) you will gain the weight back, which i did. i also have suspected liver damage from combining phentermine with aleve and alcohol.  side effects: heavy armpit sweating and mental fog."