From eight grade through high school, I took tenuate dospan which I believe is one of the other names for diethylpropion. It worked reasonably well. I lost 60 lbs. The important thing to remember about diet pills is that they all lose effectiveness over time, and you really have to work hard to develop healthy habits that will allow you to sustain the losses.
In hindsight, I believe I was far too young to be taking the meds, especially since I wasn't really encouraged, let alone taught, healthy habits. Much of my dieting at the time bordered on bulimic. I basically would only eat on weekends, eating under 400 calories per day during the week.