if he is a mesomorph he does not need our help he sounds like a ectomorph to me.....all a mesomorph has to do is lift a weight a couple times a week and he will get stronger and bigger I knew a buy who didnt even lift weights hardly in college after I left for the summer he stayed for summer school came back and he was heavier he didnt lift, but for kicks and giggles we went to the gym he benched 315lbs for 6 before the summer he was doing 275 for 6 and he didnt lift all summer just ate and ate really theres very true mesomorphs. your nephew is a ecto for sure just tell him to eat everything in sight..........