Extras Weight loss? Medicine influence?

I am starting a medicine, against my will:(, that will make me gain weight. I was told to wrap my body in plastic wrap and workout, so i didnt gain weight. Is this a good idea, or is there any better ideas? I really can't gain any weight because im trying to lose the weight from the last time i was on this medicine.(prednisone) Im starting a new school(im a junior) and want to make a good impresion. Please help me. Any ideas?