In The Walking Dead, the idea of "walkers" (roaming zombies) and "lurkers" (stationary zombies) exist in the comics. It could theoretically relate to a zombies energy level, so I'm curious - what happens to a zombie that doesn't eat? Are they weakened? Do they die (again)?
As far as I know, as someone who hasn't extensively watched the series, we don't know in the TV show.
In the comics, they come across an old zombie that hasn't eaten in quite some time. It is incapable of motion, but still animate. One of the characters
Who turns out NOT to be a researcher on the zombie virus
expresses an interest in studying it, saying something like "I wish we could get it into a lab".
You may also be interested in the responses to this related question, though I feel your question is different enough to not be an exact duplicate.
In the game, there's a part in Episode 4 where they find the zombie of a kid who died of starvation. The zombie doesn't have strength even to crawl and that became kinda depressing for the main characters to watch, so one of them decides to end this little zombie's eternal suffering with a hit/shot to the head and then bury him. It's a depressing scene.
In the show they come across a zombie that has been hanging, unable to eat, presumably for a long time, and it is as animate as ever as it attempts to grab at them.
Additionally in one of the latest (might have been the last) episode, a couple characters discuss how the "world has no future", which granted may not have anything to do with whether zombies need to eat, but you would think that they would hold out hope if they knew that zombies could die of starvation.
Since they don't "really" need to eat in order to not die (after all, they're already dead), there is no danger to them from that side. However, moving, walking, and other actions will clearly use energy, which would presumably indicate the need for some kind of nourishment.
Now, since we've seen that they can survive even with their lower organs missing, they can probably survive for a long time before eventually "dying" again. Its also unclear whether their organs are even working after they die. Muscles clearly work, as does part of the brain, but we don't know if anything else gets shut down (like the digestive system). It could also be that by not moving for a while, they could store their strength for a longer time. But in the end, they would need to get some kind of sustenance to continue moving.
I'm going to put my two cents in. My guess is that they don't really need to eat, they just use the energy from their own bodies to survive, breaking down things like cells and skin and organs they don't need as they go on. Then they get to a certain point and just kind of stop doing stuff. I think this because; 1. Energy doesn't come from no where. 2. As the apocalypse goes on(especially in the game) you can see that zombies become more and more rotted, and there are fewer fat ones left around active on the streets.
There is a comment, in the show (don't ask me which season or episode, I just know I've heard it) where someone mentions that they do starve, just quite a bit slower than humans, since they're not alive. It doesn't clarify, however, what happens when they've finally starved. (Might have been in season 2, but don't hold me to it.)
Anything in motion requires energy to stay in motion (assuming we're not operating in a vacuum, which, on Earth, we're not). Thus, even zombies, begin dead, would expend some form of energy to continue walking around, threatening, and eating people. One would assume, this is why the zombies eat other living creature, to maintain their energy levels which deplete over time.
As zombies only operate at a very basic level (a lot of our biological systems don't appear to be functioning) they probably expend energy at a substantially lower level than you or I do, but expend energy they must, and thus (if they don't eat) they will eventually reach a point where their energy levels drop so low they would cease to be animate (i.e. they would "die" a second time).
In Letter Hacks #14 and #111 it's stated Zombies eat for impulse and posess no functioning digestive system, with what they've eaten being forced out once its full, unprocessed. It's not required for their sustained animation.
Robert Kirkman wrote on Reddit:
...In the beginning of the show we saw walkers do things like using a rock to help bash the doors in or turning a door knob, is there a reason we've stopped seeing them do that?
"Older zombies are less together and capable or doing things like that. Fresher zombies, which there were more of in season one, are able to do more than older, more rotted zombies.
The worse state of older zombies holds the key; when a human starves, the body will break down fat, then muscle, followed by vital organs. The slide in mental function seems to imply the parts of the brain stem re-animated are canibalized in the process.
Since zombies do not digest, this would be how they survive, and the slower decay that stops them being a bare skeleton in a matter of a few weeks,(#9 and #11) could easily be the virus' way of preserving and stretching its 'food' source.
They would end up running out and 'starving' (in a manner of speaking), but there is no indication of how long, other than that that a surviving human would most likely outlive it, through the years, and that a zombie's lifespan would differ depeding on the individual, (#7); which makes sense, given body fat ratio, muscle density, state of organs and tissue changes from person to person.
The fact the zombies die off, albeight slowly, happens whether they eat or not.
I agree that energy out (walking) means energy in. Less energy in means less out (just standing). But even just standing, brain stem still needs energy. If no outside source, would then begin to breakdown own tissue. But the energy needs of the brain stem probably so low that breakdown of body could provide for extended period (months, years?). At some point, without energy to brain stem, bodily functions driven by brain stem (circulation and respiration) would cease. What ever flesh remains would succumb to decomposition. End result of zombie with no access to food, like any other animal lying long enough on the road side. My 2 cent
Gonna throw this out there....As stated in the episode of the CDC when they come back to life it is due to what ever virus strain that allowed them to come back with minimal brain activity. As far as the eating goes, I feel that eating does absolutely nothing for them. Eating would be a primal, instinctual act like how a dog spins repeatedly before lying down (some believe this behavior is done so the dog can find wind direction so when they lay down his/her nose will be facing the wind to smell trouble as it comes, or simply to soften up the ground). Anyway, they probably don't eat each other because even zombies know spoiled meat is bad. Over time as they rot they lose functionality until everything stops working. That being said, I think the bigger question would be why do humans not turn when zombie blood gets on a cut or in the eyes or ingested, why only when bitten or scratched..
If you think about how the human body works and especially how the muscles work, I would imagine the zombies will be able to move after a few days of not eating. You need proteins, fat, vitamins, etc.. to restore the muscles and energy. It's all Sci-Fi after all, but couldn't help myself wonder how on Earth are those zombies still moving after 4 seasons of walking dead :)) .. Not much life left on Earth to consume, just a few people, some mice, .. and I didn't see any of the zombies eat wild berries :))
they will die when they lose some primary ligament, putrefication or decompose. all the zombie will die when they run out of food. in some episodes they eat horse, rats, etc when they don't have human as a target. In Indonesia, Polmas in South Sulawesi, we have some old tribe magic that can make people who died a few years ago to get walk to their own burial place. we call it "Manenek". Come to this place if you intrinstic. In this tribe area you shall prepare all black suit, no other colour, no technology device.
Basically zombies aren't dead. they are humans who died, and then came back to life. that means, their heart is still pounding, their breathing, and, they have to eat. with no energy they wil starve themselves to death, again. When they have no food for a long time, and their stomach starts eating itself, and the brain doesn't have enough energy, the zombies will die.
ps: that means they could they of suffocation, or smth. else too.