I'm starting hcg due to low t will i gain muscle and lose weight? what are the cosmetic benifits?

None really: Hcg is not known for its cosmetic results for the face. You don't want to lose the structural fat that supports the features of the face, by extreme weight loss. It can't be replaced, except by fillers temporarily. Make sure you have this discussion with your doctor before using it, so you don't replace one problem for another. Bio identical hormones should also be discussed if you're a candidate.