Are they basically saying that eating her would be the equivalent of empty calories in the last panel there?
Since these zombies eat flesh, not strictly brains, it's more like just avoiding someone who's acting stupid. And when the half-brain-dead zombies think you're stupid, well...
Rowwwr!!Let's gooo!♪Zom-zom-zombie!Just a—wait, Ichigo!!WshWffEffectivenessWhat's with all that?A moron-zom.I'm a zombie!!!Okay, I'm off! Get ready to have full tummies!There they are!CosplayIt...TadaaahActing like a zombie...is the intent.Stay away from her-zom.It's zombie cosplay! Now they should think I'm one of them!You think it'll work...?Z-...zombie.Reckless, isn't it.It's working!