That's always been my excuse why I haven't gotten around to losing those ~20 lbs of fat sticking to my gut.

I call it the "Survival 6-pack". Silly people with great muscle definition and 2% body fat won't last a couple weeks without food. (I have been working out the last few months though)

In all seriousness though, I would tend to think that someone in good shape, without being a marathon runner would be in the best shape for a survival situation. No body fat becomes a liability as your body starts cannibalizing your muscle. Course being a fat out of shape lump could increase the chance of injury, or lessen the likelihood of you being able to evacuate yourself if need be. If it wasn't obvious, Im coming at this from a wilderness survival type situation, although I suppose it could apply to most situations.