
This plate in the lower back keep the waist tight. You can see the white muscle fibers that have decreased blood flow. These muscle fibers get thick and strong as hell but do not get volumous like the red muscles. The white muscles also take longer to repair as they have less blood flow (why lower back should be given 5 days to repair).
Now you can see what I mean with the lower back in this unusually ripped individual

Notice in the above picture that his sides grow in size dramatically when compared to his back. As soon as the muscle goes from white to red, the waist expands greatly.
Although abdominals do have these white muscles they are setup to distend by design. Abdominals need to be able to stretch for pregnancy and breathing etc. As you can see by the image below, there is a sheath covering the abdominals. However, the sides of the body are red and on top of the sheath red fibers are again present. The sides allow for distention, and the abdominals on top can expand greatly in size also contributing to the 'gut' look.
This is my theory on the gh gut but by no means do I know for sure. I just cannot find reason in the visceral fat or intestine growth theories. If people have more info that I am missing correct me please.