system
Given the following post, respond as if you're commenting on Reddit:
human
People have survived for years on extremely limited diets (POW's for example). When I read about the substances required for all the complex processes of our bodies, I wonder how this is even possible?

Obviously people on starvation diets lose weight, have little energy etc., but what about something as basic as cell replication? If you aren't getting the nutrients that are the building blocks of new cells, in the heart for example, it doesn't seem possible you could survive long. And nerve transmission, doesn't that require potassium? What if there's no potassium in your diet? How could your heart even beat without the nerve impulses telling it to?
gpt
A lot of these people *don't* survive.  If you don't get enough of an essential nutrient, you eventually die.

And that sad reality is that the people who run these sorts of camps, through trial and error, figure out exactly how little they can feed their prisoners to keep them just barely alive.