If you look at Chucks belly he has a six pack on it, thats beacause he has an enlarged stomach. Its a medical condition and has no bearing on his conditioning. Whats with all the Chuck hate? The guy is one of the best 205's ever. The guy is a legend.
No, it's adipose fat tissue. Fat that grows between the muscle wall and internal organs, typically associated with alcohol and other poor food choices. And no it doesn't really affect anything, it just makes him look he has a ****ing alien growing inside of him.