Why this is not forbidden by ICAO is beyond my comprehension.
This is a
very interesting point. ICAO can have no influence here - but the local Imans would take a dim view of hundreds of Muslims being put at risk by shagged out Muslim pilots. One approach, perhaps, is to have the local airlines request a specific edict from the Imans. 'Operating pilots
shall not observe fasting'. Reference 2:185. ‘‘God desires your well-being, not your discomfort’’.
Job done.
PS. Flight attendants included.