A lot of Muslim soccer players (Ozil, Benzema) fasted during Ramadan when they were playing in World Cup, it did not seem to affect them either, but I am not sure if during Ramadan you can't eat at all or just before the sun goes does?
Not a Muslim, but my understanding is that it's a sun-up to sun-down fast. There's typically communal meals to break the fast. I think strictly observed there's also no water during the fast, which would seem to be a real challenge to an athlete, both during the event and for recovery.
