Could also be hormones levels on Zero carb, like high cortisol.
Charles from zerocarbage also seems to have very dark spots under his eyes and he exercises a lot and seems to be doing well on ZC.
So I don't really know what it means with the eye puffyness/dark spots.
I don't feel like it's going away.. pretty much stays the same when I'm on ZC and gets better when I eat carbs (but still have puffy eyes).