The Hunger bar is placed by default above the health and stamina bar. This can be changed by using the "HudPosition" configuration option
When the player hunger level reaches zero, the Starvation effect is applied, reducing mobility and receiving Starvation damage over time. It'll add some screen and audio effects for added immersion.
When hunger drops below 20% (or as configured by the user), the Hungry effect is applied, reducing movement speed and disabling sprint
When the user is in creative mode, the hunger will always be at max, and the HUD will match the vanilla style
The hunger bar can be optionally changed to the BottomLeft corner for better compatibility with other HUD mods.