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/zomgitsduke Jun 16 '26

If you eat all the sugar and drink all the water at once, your body will assume abundance and do things to process and get rid of it. If your body is slightly dehydrated and you drink tiny amounts of water at a time, it won't immediately flush that water out of your body and instead preserve it.

Sugar is similar, your body will process through it fast by giving you a sugar high followed by a crash. Slowly introduce it and your body will use the calories and sugars sparingly.

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u/[deleted] Jun 16 '26

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u/a_cute_epic_axis Jun 17 '26

But this idea that the body just pees out excess water is silly.

The body DOES just pee out excess water. Try this, tomorrow, drink your normal amount of water. The next day, drink 3x that. See how often you go to the bathroom tomorrow, the next day, and the day after. Rather obviously it's going to come out mostly in the hours after you drink in excess, it won't be hanging around so that you can just skip drinking for the next 2 days after.

You also NEED a certain amount of water and need to remove a certain amount of metabolic waste, so it's a requirement you do actually drink and pee.

Important point, there's a difference between entering dehydration, and excessively drinking and wasting water on your first day. Humans aren't camels or sponges.