suppliments like this are meant to help you lose weight... keyword is help.
it won't do it all for you, and more isn't always better with things like this... ephedra got banned because of idiots w/ the more is better attitude who ended up killing themsleves because they abused it. it was in fact a decent suppliment when used correctly that is now off the market because of dumbasses like that
use the xenadrine as a suppliment while eating good and do some cardio in the morning on an empty stomach about 3 times a week for around 20-25 minutes.
there is no miracle fat loss pill, and all of that spot reduction shit you see on tv like the thighmaster doesn't work alone
70% of the the big picture here is nutrition, if you're not prepared to eat properly and clean up your eating habits afterward be prepared to lose very little (and be pissed off because of all of the cardio you're putting in) and most likely gain everything back.
the other 30% would be total hahahaha conditioning (weight training) and cardio. Muscle helps burn fat and cardio (especially when done in the morning) helps raise your metabolism througout the day
most importantly, make sure you have a plan... keep track of your intake and get informed! setup an 8 week program for yourself and take some before and after photos for motivation
Bill Phillips has a decent (FREE!) program out there that has helped transform lots of people (physically and mentally). I think it's called the hahahaha for life program...
http://www.hahahahaforlife.com
check it out, there are others out there but no matter how much you spend on fancy programs and pills... the bottom line is the effort and planning you're willing to put in FOR YOU