Need help saving hunger, thirst and humanity when changing playermodel

Hello there, I am working with the RottenV zombie mode and I am trying to make a Zombie RP server. The issue that I am encountering is that if I change my playermodel with any type of trainer/resource other then the actual map it will set my hunger and thirst to 0 and it will remove the humanity. Does anyone know why this is happening as I cannot seem to find the reason for it.