system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do weightlifters wear a belt on their waist?
gpt
When you lift something heavy, you have to brace your core to protect your spine and stay tight. Imagine flexing the ab muscles and much as possible, as if you were anticipating someone punching you in the stomach. Now, you need to do this regardless of whether or not you wear a belt, but what a belt gives you is something to brace against. The most simple way I've seen it explained is this:

Imagine you can squat 500lb. This means you can generate around 500lb of force, right? But if you tried to squat an empty bar, you wouldn't be able to put 500lb of force into it because you'd have nothing to push against. The belt gives your core something to push/brace against.