metabolism slowing down

my husband was searching the internet for facts on how much the metabolism really slows down while going without food. after disregarding all tests done on animals (not for animal rights reasons, just because humans aren't exactly the same thing as a test rat) he managed to find out that while fasting your metabolism slows at the rate of about 1% per day until it eventually tops out at 75%. another reading he found was that after 3 days it drops to 80% and there were no other stats after day 3. we decided that the 1%/day assesment was probably the more accurate one. does anyone else out there have any facts? what do you think? Tweet