Addendum

It occurred to me over the course of the last 2 or so hours that my brain is just hammered this morning.  I'm lethargic and achy and feel rather nasty, overall.  I'm so icky-feeling that I'm having serious trouble focusing my eyes.  So I have a theory (caveat: I'm probably not thinking clearly either; following a train of thought is really tough this morning):

I needed (still do) to readjust my metabolism to ketones.  I'm producing them right now, but can't use them.  Somehow, over the past year or so of what I thought was low-carb eating, I've returned to a glucose metabolism.

I suppose I'll know within the next day or so if this is true, because my brain and body will resume working, but it would explain why I was so crazy hungry the first couple of days trying to fat-fast, even as I failed at it so thoroughly.

Huh.