Instructions
Add the Hunger and Thirst script to the code for your RPG project by going to Tools then Database in RMXP, or by pressing "F11."
Right-click the menu in the "Scripts" tab, and select "New." Copy and paste the code for the Hunger and Thirst script, click "Apply," then enter the name "Hunger and Thirst" in the name space in the bottom-left. This code is required. Without it, the script for the Hunger and Thirst bars won't display any information.
Create another new script, then copy the HUD Add-On code displayed underneath the Hunger mechanic script. Repeat Step 2, but name the code "Hunger and Thirst HUD."