system
Given the following post, respond as if you're commenting on Reddit:
human
[ DC, Marvel, Indiana Jones, Ben 10, and various other science fiction universes] When a person is "sped through time" how come they always show the person getting grey hair and signs of aging, instead of simply starving to death from the increase in metabolism with no sustenance?
gpt
It depends on whether we're dealing with a largely physical or magical universe, but in the end it's for much the same reason they don't also gain superspeed.

Which is to mean that it typically only *looks* like they're sped through time. In more physical universes, what is actually happening is a rapid accumulation of defective proteins, flawed mitosis, creation of cellular debris, DNA damage etcera.

It's sort of like the difference between actually letting a machine work for ages until it rusts and intentionally engaging in some chemistry so that it rapidly oxidizes/forms rust. The end result may *look* similar, but only one is actually due to passage of time(in the latter case, you won't see material wear-and-tear for example). A machine rusted through an intentional chemical reaction can still have a full battery - the same applies to living organisms/metabolism.

In universes whose laws of physics contain magical forces, it's because such magics generally don't involve the energies of Time - they involve energies of Death. That is, such magics typically forcefully move you closer to death/rip away your life, the physical manifestation of which usually looks like rapid aging.