You didn't specify what exactly you wanted to achieve at first.
local function OnNewSpawn(inst)
inst.components.hunger.current = inst.components.hunger.max * 0.75
inst.OnNewSpawn = OnNewSpawn
Put the last line in your char's master_postinit.
About the health part I'm not 100% sure, but probably it should be like this:
inst.components.health:SetPenalty(-penalty value here-)
I'm not too sure about the penalty value (if it should be percentage-based or how many 'penalties' should be added), so you can just try and put "3" or "0.5" or something, and see what happens.
Hope this helps.