Please don't starve yourself for six days. Nor 5, or 4, or … just don't starve yourself. When the body is not consuming any calories at all for an extended time, it turns to protein first for fuel. That means muscle. You will lose MUSCLE for a long time before you lose fat, and that is very dangerous, especially to your heart muscle. read more
The most weight a person can lose in either fat or muscle is ½ pound per day, says Joanne Larsen, RD. Any weight loss beyond this amount is water, but once you replace that water, the number on the scale goes back up. The body is reluctant to move fat out of storage to use during a fast because it needs it to keep you alive when it perceives it is starving, says Larsen. read more