that is a good deal of fat loss. how muc bounces back depends on how much lose skin you have remaining and possibly other factors like how long you were fat.  at your age, you still will have a good amount of elasticity and ability to "pop" back after fat loss. in competition dieting, there is always a point in the diet for me, that i lose fat and water but the skin still hasnt tightened up around my smaller midsection. over a few wks, it eventually does but i'm not losing massive amounts of fat. gh may help, but it isnt going to work a miracle. 2 to 4iu a day would be a heathy dose. not knowing how much skin you have, its hard to say if it is going to work. this may be a situation that you have to see a dr about having the extra skin cut off if it is excessive. besides gh, let me share a couple of tips that i use. tanning in the tanning bed dries the skin out and tighens it up some. also, i wear a sweat belt while doing cardio to help push extra water out and shrink the midsection. you may want to look into vitamins for the skin too. i use 400iu of E every day. it may help improve elasticity