A normal fit person who has had a (usually copious) meal at, let's say 22;00 and six hours of good sleep will NOT be hypoglycemic when they wake up. Their blood glucose should be towards the low end of normal and will actually rise somewhat as they get busy. The body has plenty of glycogen reserves in the liver and muscles. If they continue to fast they may get thirsty after a few hours, but that'll do them no harm. I reckon that it would be at least 36 hrs before their blood glucose started to fall to such degree that they cannot fly a modern aircraft safely. They'd certainly be hungry.
I certainly done gigs like that and never felt faint, though you can't keep sharp indefinitely!
In an open boat, three days without any water, three weeks without any food is about the human limit
So I don't take that Ramadan stuff seriously, unless they were complete wimps.
Crusty Mac