I did a three day fast.  I believe I had a virus when I began the fast as I
had diarrhea and a low grade fever, both of which went away immediately the
morning of day one.  Day two was the toughest, especially dinnertime/late
evening.  Anyway, here are some excerpts from the journal I kept:

Day One
8:30am first mild hunger pang; weight 155.5
11:30am stomach slightly rumbly, but I'm fine.  Even slightly euphoric.
4:08pm hunger not an issue; rumbly stomach, cold hands

Day Two
5:00am woke up with headache and sore jaw; fairly restful sleep, though
8:02am feeling weak, mildly hungry; mouth tastes steely and gummy; urine
still has color though I'm drinking plenty of water
9:57am feeling even weaker; and as hungry as I've been yet
12:44pm weight 153.5, bp 120/72; little bit of nauseau, not much hunger
2:30pm walked 1.5 miles and felt good while doing it; but felt very weak for
hour afterwards
4:24pm color in urine, hunger good; wt 153, bp 124/74

Day Three
5:00am headache and nausea when I woke (as a male, I'm pretty sure I'm not
pregnant)
7:30am went for light workout with weights; wt 151; amazingly, didn't feel
the slightest bit weak after the workout!  (Weakness has all but
disappeared)
9:45am took 30 minute nap; still feeling a little nauseous but not much
hunger; mouth still tastes gummy; wt 149.5
5:00pm broke fast with meal of flank steak and spinach in garlic and olive
oil rather than easing into with fruit as most sources recommend; upon
taking my last bite, the diarrhea came back with a vengeance (it was as if
my body took a complete break from the virus while I was fasting)

Overall a fascinating and, yes even spiritual experience.  I continued with
the ketosis for a week afterward and continued to lose weight until I got to
the mid-140's, which is too light for me so I've added fruit back into the
routine and have since gained back about two pounds.

As for the law school thing, you could do it.  But expect the first two days
to be the equivalent of the difficulty you'd encounter if you had a pretty
bad cold.  It probably wouldn't stop you from going to class but would be
uncomfortable.

Let us all know how it goes!