I think you'll be fine. Take note of your energy levels and strength throughout the weeks, as well as your appearance. This will give you a true indication on what's happening with your body.
Purple Wraath is awesome - it's what I used while running my IF diet and training after a 16 hour fast - and I definitely lost no LBM, strength was through the roof in fact. I'd consider complex carbs in that post-cardio meal, vs. the banana.