"i have lost 35 lbs. so far on phentermine. i have a lot of energy, but the trade-off for me is lack of a good nights sleep. i also have noticed that, unless i have been off of it for at least four weeks after being on it for five weeks i don&#039;t lose weight and my appetite is not under control. my doctor does this so that i don&#039;t become dependent and require more to lose weight. i am trying to get more exercise, but i am not good at getting out there as much as i should. also, i need to control my carbs better. that, along with the exercise is key for me. good luck to all of you trying to lose weight. "