How do you know when you're hungry in Minecraft?

Answer 1

Your hunger bar is represented by a row of chicken drumsticks. Running, swimming, etc, will make the drumsticks start to disappear. When they are all gone, your character is starving and will lose life, down to 5 hearts in Normal and 1/2 in Hard.

Note that if you play on Creative mode, there is no hunger bar, and if you play on a Peaceful setting, your hunger bar will never deplete so there is no need to eat.