Fasting usually occurs at 6-8% remaining on the food bar and this message shows in the [[event window]]: "Your hunger goes away as you fast.". If player has fat layers then each fast will reduce a player's nutrition by 20% to a minimum of 10% where it cannot drop any lower.
As a player is able to feed itself to 100% food, it will become "[[player status effect|full]]", which means the food bar is over 84%. Over time, being "full" generates fat reserves on a player which can be observed by examing examining your body in inventory or another player by right-click and [[examine]], which will state how much fat the player has:
* only skin and bones