I started training when I was 13. I did it right from day 1.....I started at the end of 8th grade at a skinny 175lbs, and I was 215 the end of my freshman year in high school....I ate everything in site, I'd make an 1800 calorie weight gainer, then eat a snickers bar and some whole milk, then go to Burger King and drink a milkshake and have french fries, I just ate and ate and ate.....I have no clue what my bodyfat was, but my waist was not any bigger and I appeared to have put on mostly muscle......If I ate like that now I'd be fat as fuck, but at 14 yrs old you can do it.....for any younger guys out there, I advise you to eat everything in site, with your hormones raging the way they are at 13,14,15 yeas old, you are not gonna get fat as long as you train hard, and you'll be glad you took advantage of a time in your life where you will make the most gains possible, and you can literally turn yourself into a denser, more muscular person for the rest of your life.