Hi, i tried out the game and i have questions about stamina/fatigue/calories. How it works?

After a while my character started to stop very often, and i felt the game unplayable because of this. It's like stop every 2 sec, and wait too long to walk 2 sec again.

Eating gives calories: Thats the blue bar below your red, hp bar? The more full the blue, the more you can walk without rest? (i see the masuring meter (or how i say this) above it, thats the fatigue, how much you can run without rest i guess?)

At the start of the game i walked so long  without resting.  Around 2nd or 3rd day, ate all food, blue bar is around 60-70% and i can't walk more than 2 sec. Is it normal? I should stack on food like a moving shop or what?

Thanks!