I've done KB workouts for the last few years, and have also done IF (8 hour fed/16 hour fast). I would work out in the morning fasted, and usually not break my fast until about 1 p.m. I've tried ingesting BCAAs before/after my workout, and also done it completely fasted.
Recently, I stopped IF to do a Whole30. I'm now eating a little protein pre-workout, a protein/carb meal post workout (usually a turkey-sweet potato hash), and a fat/protein focused breakfast about an hour after my post-workout meal.
For me, switching from IF to eating has vastly improved both my workouts AND my body composition. Although I've enjoyed my experiments with IF over the past year or two, I would say that for me, I'm getting better results without the IF.
“If you want to build a ship, don't drum up people together to collect wood and don't assign them tasks and work, but rather teach them to long for the endless immensity of the sea” -- Antoine de Saint-Exupery