Originally Posted by T-Rod45
According to the authority in modern-classic (Romero-esque) zombie folklore, Max Brooks, a zombie has no metabolism outside of the brain. The Z-Virus, keeps the brain going, and the body continues to rot and wither until it turns to jerky... This is all of course physically impossible, since you need muscles to move...
He also mentions that the Z virus also makes the bodies much less accommodating to the usual microbial suspects involved in the decaying processes. Essentially, not even bugs or bacteria can thrive in the presence of the virus, so normal decay takes significantly longer.