Im 16 and for my age and height I lift alot more than anyone else. I only workout for 30 minutes a day 5 days a week but I get hella gains. I eat my vegis and meat and protien and all that good stuff. I have recently started intermittent fasting which increases Human growth Hormone by up to 2000% depending on how long you do it. It also makes your body burn fat and preserve muscle. You should look into it.
if you are skinny let the body burn fat and eat carbos and protein. adn if you want a better condition you need train more that 30 min... 1:30 with good rest will be great