The relationship between fasting and physical condition and fasting's use/roll in training is not well known. However a number of athletes have used it with good effect or better.
Sorry this is "old research" my memory is not good enough for names.
My own personal experience tends to back this up:
After some fasting history, one of fastings most attractive qualities is knowing the physical/mental "hyping" that can be available. What I call my full buzz state. Knowing it is available and how to induce it through fasting is powerful. The state in which I prefer to live. The other thing that happens is the ever increasing connection/understanding to what both food and life style do to you. Knowing the "Buzz State" gives me a good means of self assessment.
I would back all the food advice above with one caveat. Become increasingly aware of just how individual, complex yet knowable your own "condition" is. Slowly at first.