How much weight will I loose in a 5 day fast I am 5 feet 1 in. and weigh 150 lb. How much weight would I loose if I didn't eat anything but drink water in 5 days?

If you stop eating, your body will go into "survivor mode" & will start to shutdown & you will not lose any weight. Weight lose needs to be done safely over a reasonable period of time ( months ). A proper diet & exercise is the best way to lose weight. You will not see a significant lose in just 5 days.