system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it that it takes few seconds for our body to decide that it's had enough water not to be thirsty, but several minutes to recognize that no more food is needed cuz it's not hungry?
gpt
Sensors in your mouth, back of the throat and oesophagus can detect how much water has been consumed and report this information to the brain. Fairly shortly after drinking water, the bode will start to behave as if that water is already in the bloodstream, even if it is still somewhere in the digestive tract.

Food is a completely different story. The brain relies on stretch receptors in  the stomach, hormones produced by the process of digestion, and sometimes chemicals generated by the bacteria living in the intestines. This is a much more complicated process that takes longer, which leads to a lag between actually being full, and the feeling of fullness.