Ismaili coach Mark Wotte pointed the finger at the Confederation of African Football (CAF) for his side's defeat at Heartland after it rejected the club's request to alter the timing of the game.
Heartland secured a late 2-1 home victory over Ismaili on Sunday afternoon in the African Champions League to dent the Egyptian team's hopes of reaching the semi final.
Ismaili players refused to break their fast on the 19th day of Muslims' holy month of Ramadan and Wotte believes their energy was sapped as a result.
"I don't want to speak about religious issues but the fasting affected my players today," Wotte following Ismaili's third group-stage defeat in four games.
"CAF is to blame for that because it forced us to play during the day, it should have changed the timing of the match.
"Food is very important for the players. They couldn't perform well in the second half, they lost energy and concentration."
Ismaili's defeat leaves them at the bottom of Group B with three points.
Heartland lie third on four points, five behind leaders JS Kabylie of Algeria and one adrift of Egyptian champions Ahli.
Ahli and Kabylie meet at Cairo Stadium later on Sunday.