I wanted to post a picture I stole off the BFL board, but the site won't let me post the same graphic twice!
Anyhow, it shows what a pound of fat looks like compared to a pound of muscle. I can't think of a better graphic to get across the point that you can not lose numbers, but you can lose inches. You can find it at the following link:
Home of the Loozing Floozies....(#78)