I had a terrible reaction to a diet "stack" in high school. One of my good friends in an herbalist, so I do use supplements- Tonalin CLA,(helps build muscle) Alive! Multivitamin (the best multi anywhere!!! I love it) Coral Calcium, Chromium Polynicotinate and EGCG (the active compound in green tea) I take Evening Primrose Oil and SAM-e during my time of the month if I am having a hard time.
Exercise is the only way to increase metabolism and if you have all your nutrients, your body won't go into starvation mode. I did see a lawsuit on TV against one of the cortisol weight loss pills (not sure which one) due to unsubstantiated claims. Sometimes it's just a psychological boost- you think it's working so you eat better, etc. In that case, as long as it isnt' harmful and your doctor says it's ok, there's nothing wrong with taking it- even if it's not magical, if it psychs you up, the weight loss could result indirectly. I would research products and ask your doctor- together you can decide if it will work. Never mix diet pills (take 2 or 3 different ones) though.
Good luck! Let us know how your results are!