you should be fine, but just be prepared for a little extra dizziness, and you might feel the need to take it easy a bit in the yoga class. i did a long weight lifting workout one day on the fast, and then layed in the sauna for 20 minutes or so, and when i came out of the sauna i had to sit down for a few minutes because i was very weak and dizzy. the sweating and activity releases extra toxins, too, so you might not want to plan other things after your yoga class, as you may be weak for the rest of the evening. but it's a great idea to excercise while doing the MC, in the end you will get better results, and you may alleviate some sickness symptoms by sweating the toxins out so they don't build up.
good luck, happy yoga!