I am 15 and i started lifting last year in really have gone a long way. I use to ben 170 of pure fat and now im 165 with about 12 percent bodyfat because im bulking. I use to be about 6 percent BF but I think lifting helped girls notice me more and gave me more confidence in myself about everything. Just teach ur bro good form, tell him its not all about ego, and teach him out to eat the way a bodybuilder should, and he will turn out to be a monstar.