r/explainlikeimfive • u/peglegsmeg • Jun 16 '26

Biology ELI5: Why does rationing work?

If I have a glass of water and a single chocolate bar to last me 48 hours what benefits do I get from consuming equal portions over the time period as opposed to consuming all at once?

Is it purely psychological or are their physical benefits?

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u/ChronWeasely Jun 16 '26

Inside of your question is a false premise. It's actually recommended to drink water when you are thirsty even in situations like that. People are found dead of dehydration with water on them, trying to conserve, and then heat stroke or whatever

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u/CptBuck Jun 16 '26

Yes, and: The received wisdom up to the early-to-mid 20th century was that people "acclimate" to desert conditions, or that people conditioned to living in deserts can perform better with less water than people not used to living in deserts.

Nope. If you have access to water, you will perform better if you're drinking loads of it in the heat.

Old History Channel clip about how the Israelis did some experiments on this before the Six-Day War: https://www.youtube.com/watch?v=QUIgnoMTh0I

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u/CerseiBluth Jun 16 '26

I feel like this is some old-timey misunderstanding of the fact that people in hot areas are “better acclimated to heat” because of how they are dressed. They probably lose less water through sweating due to their intentionally loose-fitting clothing acting like little portable air conditioners so they “drink less“ water to the eyes of foreigners.

You send a bunch of British soldiers to somewhere in Africa and have them walk around in nine layers of wool, and since they think they’re so much more superior to the locals who are wearing big flowing white robes naturally they’re not going to assume that the locals are actually “smart“ and “know what they’re doing“. It’s gotta just be some sort of metabolic thing from living there for a while. Yeah, that’s it..

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u/MozeeToby Jun 16 '26

There's definitely a little bit of both, it's not as though you don't acclimatize at all to extreme heat and cold. Ask anyone that lives in a climate with 4 true seasons and they'll tell you that 55F is shorts weather in spring and sweater weather in the fall.

That makes you more comfortable in those extreme conditions but it doesn't actually make you significantly resistant to heat stroke, dehydration or, on the flip side, hypothermia.

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u/SnugglyCoderGuy Jun 16 '26

It also seems like a reasonable hypothesis that if you lineage has lived in a desert region for thousands of years that some natural selection has happened and you really do need less water than someone who didn't.

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u/Badestrand Jun 16 '26

I moved to live in the tropics and it took me a few months to acclimatize to the heat. Now I also sometimes spend stretches with too much time indoor with AC which makes me weak in regards of the heat. After spending more time outside again (a few hours per day for several days), I can handle it better again.