What have you tried so far? It is rendered in the renderFood() method in the GuiIngameForge class. If you want to change it I think you need to create your own class that extends GuiIngameGuiForge and replace the public field called GuiIngame in the Minecraft class with instance of your class. Then you have full control and can change the renderFood() method in your class to draw it however you want.
How do I expand the default minecraft hunger bar?
What have you tried so far? It is rendered in the renderFood() method in the GuiIngameForge class. If you want to change it I think you need to create your own class that extends GuiIngameGuiForge and replace the public field called GuiIngame in the Minecraft class with instance of your class. Then you have full control and can change the renderFood() method in your class to draw it however you want.