You May Not Want to Talk to Me Tomorrow

Or at least not before late afternoon; I have to go for a complete, routine body chemistry make up/check up (I know there is a better word, but it escapes me at the moment) at 3:10 p.m. Wednesday, and I have to fast for 12 hours before that.
So, I will be operating on no coffee and no food throughout my waking hours and work day; if I seem surly, bitter or unpleasant (OK, more than usual), you will know why.