Skinnydude, your 16 so there is a chance if you start lifting weights someone, most likely someone older, is going to say “ooooo don’t lift too much now, youl bend your bones/stunt your growth/turn into a hairy-chested hobbit”. This is in fact a load of crap. If they do give you this, direct them to this review article,
Hind, K. & Burrows, M.(2006) Weight-bearing exercise and bone mineral accrual in children and adolescents: A review of controlled trials, Bone 40, 14�??27
Basically point out that resistance training (such as weight lifting) increases bone strength. Its also a review so covers a lot of work, not just one experiment. There are several problems with the experiments covered but it is still interesting stuff that can be used to get people to shut up.
Also when trying to get protein powder, providing you dont have a job, try the old “your not happy with your body and you get ignored by most girls for being too skinny”. Basically guilt trip your parent’s into getting you the stuff, use what ever you think will work.
Hell if they say you should be focusing on your studies let them know supplements can enhance mental capacity. If that’s true or not i have no idea (apart from fish oil).
Other than that, just follow the advice already given and for god’s sake (well really your own, i don’t think god has teeth) stop drinking fizzy shit.