you are young and if you lose steadily and not too fast you will be fine. Rememebr to always drink heaps of water, as it helps with elasticity, and green tea is said to help too. Invest in a good all body moisturiser too and slather it on after a shower!
Hydrated skin is stretchy shink.
Im 25 and had 35 kg to lose and i havent had skin problems yet *knocks wood*
Life is too important to be taken seriously!