Why does my body signal I'm not thirsty/hungry immediately

First, OP, get an idea of what "hunger" really is.
It's not your cells telling you they need energy
it's just a feeling, your body telling you to eat something, nothing more
with a bit of training you can entirely overcome that feeling but that's another story
it has nothing to do with digestion or chewing food

>>8163179
>inb4 but there is no feeling
>buddha was stupid!

>>8163184
>>buddha was stupid!
is that some dank /sci/ meme?
I'm not here very often

>>8161977

Might have something to do with stomach weight/pressure (it has limited capacity), I don't know.

Homeostasis: positive/ negative feedback mechanisms

When you're doing digestion your stomach releases hormones that say you're fine now. Stomach distention does a little bit of that (ex: drinking water to saciate hunger) but that doesn't last.

>>8163179
>good news, fat people! You can stop eating now, the hunger is all in your head!

>>8164470
it is. you never fasted before?

all about hormones, senpai.
Takes a while

Technically digestion starts the moment you start chewing. Think of your mouth, esophagus, stomach, large/small intestines and anus as one large cohesive system.

According to Wikipédia, grhelin is a hormone that gives you the feeling of hunger. While you eat, sugars are recognized (papillae) and kickstart the release of insulin. The brain receptors' affinity for grhelin reduced by insulin and leptin, a hormone that gives the feeling of satiety.