Sure it's possible but I sure wouldn't do it that way.  If you lose a large amount of weight in a short period of time then you will have HEAPS of excess skin hanging off you.  As long as you don't have any major pressing health conditions that mean you need to lose it ASAP, I'd aim for losing 50lb a year max so my skin had time to shrink. Oh hell, I'd never get that fat in the first place but if I did.