I actually took it when I was 17 and gained around 8lbs or so, though honestly I wouldnt attribute all of that to M-Stak. I still wouldnt do it again because I got some pretty bad acne while on the stuff (though I am prone to mild acne, I had never had it as bad as while I was on m-stak), probably from the tribulus. I would look into a CEE based stack as I and many others on this board are having great results with this product and its safe for you to take.