How can i loose weight extremely fast ?

i used to be skinny but there have been alot of occions recently and i have put on alot of weight. i have a gf hu i havent seen in a while... if she sees me like this its over but i love her n cnt let tht happen... i can handle a diet but whats the quickest way ?!?!!? is it possible to alot of weight in a week or 2 ????