Teenager Cannot Gain Weight?

I'm not exactly sure what this is like since that's not my body type...or gender... but muscles are heavier than other types things in the body like fat, so I recommend working out for muscle growth. As in trying to get ripped teehee. So try and get in some reps on the weight training circuit and eat some lean protein like chicken or fish so you aren't risking your heart with red meat overdose. Protein shakes and powder are also an option, but I've personally never tried those. Look on the web for some exercise videos with hand weights, or sign up for a gym, or perhaps look into a personal trainer. Another thing I recommend is talking to your doctor, since they are like "the ultimate health guru"