In the 28 Days flick the “zombies” actually did run out of energy after a while and kind of rotted away.
28 Days Later is the most plausible of the whole genre. It’s also because they are not true zombies, meaning they are not dead people brought back to life somehow. They are living humans infected with a virus that causes them to fly into a murderous rage, and will die eventually because outside of cannibalism, they can’t really feed or take care of themselves.
since these bodies wouldn’t be making any collagen either, they’d hardly be able to stay togethger, much less tear stuff down, or grab anyone with force.