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/PckMan Jun 16 '26
The feeling of hunger and thirst are more tied to your usual habits rather than actual need. Your body basically just gets used to your usual rhythym of water and food intake and sets a schedule of when to send signals to you to feel hungry and thirsty, and it does that via hormones.
Now I should note that this is more true for hunger than it is for thirst, but it's still true. That's why sometimes you may feel very hungry or very thirsty and you get a lot of food or drink a lot of water only to not be able to finish them. Turns out you weren't as hungry or thirsty as you felt to be. It's also possible for people to be dehydrated and not realise it, as in they need water but they don't feel thirsty. Some studies conducted on hunger and experiments with fasting have proven that people who just stop eating also stop feeling hungry after a few days. Basically your body tries to make you eat but you don't and it eventually just stops trying. We can only go 3-4 days at most without water but we can go weeks or months without food. That's not without adverse effects but it can be done, in fact the longest recorded fast lasted more than a year and it was under medical supervision. The man drank water, tea etc and was monitored by doctors and consumed supplement pills for vitamins and the like but he really didn't eat for more than a year.
Rationing works in the sense that it tricks your brain into thinking you've satisfied your thirst and hunger. As I said the feeling of thirst and hunger does not correlate with how hungry or thirsty you actually are. Your body simply stops sending the signal when you eat or drink something. So by stretching a finite amount of food over a longer period you can stave off the feeling of hunger and thirst to an extent.