I had a player on my high school team that played during the fasting. His play did not drop off at all, but I would sub him out more often (in american high school league we can sub players, in and out, whenever we want to let all the players get playing time). He seemed to think he was more tired, but it did not show in his play. His performance was not worse, it almost seemed to be better, he had god on his side as he played then, he was a happy player...