This is my personal theory on how zombies gain their energy to keep un-living. I'm a believer in Max Brooks zombies and i have tooken his theory and improved upon it in the following aspects energy suppy is the biggest one and i believe the zombie virus takes energy from the bacteria that break down a dead body. In doing this the virus kills to problems in one act. It gets fuel to live and stops the host decay. I also think the virus takes fuel by breaking down stomach connent independently of the body's natural disuestive tract which is dead.