system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does your body go into withdrawal when you try to quit drugs or alcohol?

If the drugs and alcohol are bad for your body, shouldn’t your body have a happy celebration when you try to quit them? Instead your body brings you to the brink of death with withdrawal symptoms.
gpt
Your body always wants to reach a "balanced" state known as an equilibrium. If you regularly use a substance that provides additional chemicals or signals (stimulants), your body will respond by producing less of those to balance it out. Likewise, for substances that block chemicals or signals (depressants), your body will try making more of them.

Withdrawal happens when you stop supplying the substance. Now your body is either greatly lacking or greatly producing certain chemicals or signals, causing a series of other uncomfortable to fatal symptoms. The easiest way to reach your previous "balance" and stop withdrawal symptoms is to continue taking the substance, making these physical additions difficult to overcome.