One thing I've noticed is that plasmamen need to eat in order to keep their nutrition level up. Considering that they get the energy they need from the plasma they breathe, it seems a bit odd that plasmamen would need to eat to keep their hunger levels up when plasma has taken over that function.
The wiki (which I understand is a work in progress) states that "While they can no longer eat food or breathe normally, they can inhale and combust small amounts of plasma gas in their altered lungs", and "This reaction both provides them with metabolic energy and helps to stabilize the solidified plasma in the rest of their bodies."
My suggestion is that their nutrition levels could be altered by the amount of plasma gas fed to them, or that it just stays static due to the constant need for plasma anyway.
