I'll give you a reason that has nothing to do with your health:
6'3'', 160lb.
Thats enough, unless you know you have low IGF/
GH, Testosterone or some other homone problem.
You need to have your diet and workout dialed before bothering or you will be wasting your time. Either you won't gain much, or you will loose it very quickly. So you'll be taking a risk (same as anyone else, even without health issues) without an obvious benefit.
But, maybe you'll prove me wrong and put on 15lb easily and keep it and be happy. You'll never know until you try, all we can do is give you idea/points to take into consideration so you can asses the risk/benefits for yourself and take responsibility for your actions.