When you can see a spine, and the body looks like it has too much skin, it's way too thin.

About the only way to accurately tell without waiting that long is a gram scale.

"Best Buy" has one for around $40 that works great.

I know how expensive vet visits are, but I love my animals, so I just grin and bear it. ($65 just to walk in the door!)

My vet thinks I'm cool. (Why not, I bring her WC snakes to treat) but not many people come to her office with Garters)

Best luck,
Wayne A. Harvey