sub-optimal sleep will obviously affect you but not as much as calorie restrictions. One day of calorie restriction might not be enough to cause too much of an impact, but subsequent days can kill your will to push yourself. Simply don't have any fast burning fuel in the gas tank. For important sessions where you care about your numbers, you have to fuel up (calories + hydration) good the day before.
I have ALOT of experience with calorie depleted sessions (dunking, running, lifting, etc). The real key is to acknowledge it early and not care about the numbers. You can still work on technique and go sub-max to get some work in. But even attempting max effort can be pretty impossible & take much longer to recover from.
I used to love dunking when very hungry.. I'd go without food for 6-8 hours or so (and just drink milk+coffee 30min before) to get this hungry-light-jittery-ampd feeling. However, the day before, i'd eat ALOT. So there are some tricks you can play but legitimate calorie depletion is only going to make you much less powerful.
you probably know that, but just stating it in case. If fat loss is such a primary goal right now, expect extremely zig-zag performance.
pC mutumbo!