Young athletes are constantly striving to be bigger, stronger, faster. Peruse professional sports and you’ll discover examples like Giancarlo Stanton to Adrian Peterson, from Lebron James to Lolo Jones. No matter what your girlfriend tells you, size matters. For that very reason, when a young man or woman approaches me about gaining weight, I take it seriously. I’m often asked by the leaner types with less muscle mass how to put on weight. Recently, in fact, a college baseball player expressed in writing that he’s tried weight gain shakes and eats like Homer Simpson but has had difficulty packing…