If I were to fast for 21 days, I have a fairly fast metabolism, and I'm already thin, would that be okay? I'm 5'4", and about...121 pounds now. I do know that the weight I lose, some will come back, but my main concern (and I've asked this type of question before, but I never went through with a long fast) is looking really scary skinny during the fast, because I don't want to raise a concern with people. From what I've read, people tend to lose about a pound a day, sometimes more, sometimes less. If that were the case with me...that would put me at about 100 pounds at the end, which is rather underweight and I do not want to look like a skeleton, I'm doing this for cleansing.