The question itself is not specific enough to get accurate results. To be accurate, you have to account for age, height, weight, activity level...and even then, everyone's bodies are so different that a concrete answer remains elusive.
My equation came from research via google that was corroborated with the math I did on own weight stats.
I'm not sure what the comment above about muscle had to do with it, but maybe there's something there.
Interestingly enough, when rechecking my data just now I came across a thread on this site that revisits both sides of the convo here.
http://www.3fatchicks.com/forum/showthread.php?t=62544