Answer:
When you start to drink it you can see some weight loss (few lbs) in few weeks (but only if you are working out also).
Just work out, its the best you can do, trust me, I am 18, and I tried many weight loss stuff when I was 13-16, didnt work that much, only thing that helped me lose the 20bs that I did to get to my 135LBS (i'm 5'7") Was working out.
That's how ALL the celebs get where they are fitnes wise, they don't drink any "special" drink. They work out like crazy. (Again you might have to work out a little more cause they have Trainers) but if you work at it (be on a proper diet, and work out as much as you can) you will lose the weight that you want to :)