I am just wondering if its good for a fifteen year old to be taking a bunch of pills. I mean your body is going through some pretty major changes by itself and I am not sure adding to that is really helpful. I am not saying its bad, but I question the benefits. I would argue a glass of OJ and heathly meals would be of more benefit. I know when I was fifteen, just 8 short years ago, I didn't eat like I should have. Granted we had sit down meals, I drank wayyyy too much pop and snacked too much. I was by no means fat, but I noticed I really started adding muscle when I watched what I ate more then taking anything from a GNC store.
On a completely off-topic note, don't beleive everything you hear at GNC. I had a girl trying to sell me some new powerbar because "it has the highest concentration of protien and thats what gives you energy. that's why people can cut carbs and still not feel tired." I just said no thanks and bought my clif bars.