This reflects back to the old saying, if it sounds to go to be true. Most likely it is. Losing 10 lbs in 3 days isn't good for you in any way. If is water weight, the chance are you have dehidrated yourself and the first drink of water will gain that back in 30 seconds, and if you continue on that part. You wouldn't have to worry about it much longer, Your family will when they have you fitted for you burial dress.