You can find the hunger settings in the BP_PlayerInventory then select the Class Defaults button to show the blueprint settings in the Details panel. You will then see the hunger settings like the image below.
Use Hunger – If true the character will use hunger, if you do not want to use the hunger system just untick this option.
Hunger Reduction – (As seen in the image below) Using these settings you can set the amount hunger will reduce while in a character state.
Max Hunger – This is the max amount the hunger value can be set to.
Starting Hunger – This is the hunger value that will be set when a new game is started.
Hunger Reduction Time – This is how often in seconds the Hunger Reduction values (As described above) are subtracted from the current hunger depending on the characters state.
Starvation Damage – Is the amount of damage the character takes when hunger is at 0.
Starvation Damage Time – Is how often in seconds the character takes Starvation Damage.