What does depletion of glycogen have to do with hunger/being "physiologically fine"? People who are ketotic after about 1 or 2 days, or people who have just hit

What does depletion of glycogen have to do with hunger/being "physiologically fine"? People who are ketotic after about 1 or 2 days, or people who have just hit "the wall" during an ultra-long workout, don't have much glycogen to go on, but still get hungry just fine.