Eli5 Why do mammals put on weight depending on how much activity they do and calories they consume
In: Biology
Fat (although not the kind of fat you eat) is just the way the body stores excess energy. Because in nature food is scarce and/or unreliable, your body doesn’t want to not use energy you spent the time and effort to consume. So instead it converts those sugars into fat, which it can easily consume later.
Eating adds calories and activity uses calories. You store calories If you consume more than your activity uses. This is done so you can miss a few meals and still be okay.
It’s not just mammals – lots of animal’s life cycles have evolved around storing lots of energy when food is plenty (e.g spring/summer), and using these stores to supplement their diet when stores are scarse. (winter) Many animals would simply die in winter if they couldn’t build up fat stores.
The more you eat, the more excess calories you have so the faster the body converts these calories into fat. The less exercise you do, the less energy you burn so again you have more excess calories to store up as fat.
to be able to spend it, literally.
Your body doesn’t want to spend energy. The ideal scenario for your body is: you laying down, getting feed in the mouth by someone else and sleep all day (not saying that you want it, but that’s how your body behaves).
So, if you start using these calories, your body will try to find “a new normal” and require for you to at least eat the amount spent back in.
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