If you researched a bit, you would find a number of cases where people have tested the hunger and thirst system. When you spawn you have around 50% or so of thirst and hunger. When he says I could use a drink etc. that means you are under 40-50%, if you drink and eat untill you get the message my stomach feels full or something like that, you wont have to eat for atleast 30 min. The system is pretty balanced atm. you just have to eat enough. Search the forums before posting something like this next time.