There will be about 3,500 Muslim athletes at the London Olympics. Those who choose to observe the Ramadan fast during the 17 hours of sunlight each day in England will face special challenges as they train and compete.
It often comes down to personal choice, as many athletes have been granted the option of postponing their fast. The two Emirati Olympians whose sports are defined by what they weigh, for example, will take contrasting approaches to fasting while the Games and Ramadan overlap.
Khadija Mohammed, the 17-year-old schoolgirl who will become the UAE's first weightlifting Olympian, intends to keep to her fast for all but the day of her competition itself. Her teammate, Humaid Al Derei, the Abu Dhabi-based judoka who will compete in the 66kg division, plans to postpone fasting until the competition is over.
By the nature of her sport, Mohammed's weight is always carefully monitored. She will be entered into the 75kg category, meaning she cannot exceed that weight.
At a press conference last week, she undertook the sort of weigh-in which is normally reserved for fighters ahead of a boxing bout. She tipped the scales at 73kgs then, and the sport's governing body expected there to be a noticeable fluctuation as she had just flown in from a training camp.
The competitor's weight is so integral to her sport that maintaining the ideal weight while fasting will need to be an exact science.
"Khadija will not be fasting during the day of competition," said Jassim Abdulrahman Al Awazi, a board member for the Emirates Weightlifting Federation and the GCC Weightlifting Organisation.
"However, she plans to keep to her fast on training days, but will carefully monitor her blood sugar levels to make sure she can still train effectively. She will be keeping to her fast as much as she possibly can."
Al Derei, 21, has experienced a similar situation before, and it worked well for him then. He secured his qualification berth for this Olympics when he won a bout at a competition in France last year which fell during the Holy Month. He began fasting the day after the competition.
"When you play you should not fast," he said. "When I was playing I was not fasting, but I started fasting the very next day.
"In judo, one five-minute fight is like playing football for two hours. For example, footballers have good condition when they are running for two hours, maybe more so than me.
"Maybe if I played football, I would tire after 30 minutes. But if a footballer came to do judo for five minutes, after one minute he would have to finish. He would [be very tired]."
Athletes who choose to fast will have their work cut out to maintain the same weight, according to a nutrition expert.
Nick Worth, the medical services director at Al Jazira in Abu Dhabi, says weight gain often occurs during Ramadan despite the long hours where no food of water is taken.
"At the club what we would do is weigh people every day and plot changes over the four week period, to see if they are losing or gaining weight," Worth said.
"The reason why people might gain weight during Ramadan is, because of the fact they are not eating the rest of the time, they then have relatively high sugar, or carbohydrate-rich foods. They are often the sort of foods eaten at a family iftar.
"A lot of the time people gain weight because they actually eat a lot over the evening and night period. Because it is a celebration, overall the calorie intake could go up if it was judged over a period of a whole month."
The UAE's Olympic footballers were granted an exemption from fasting, on account of the travelling rather than the physical exertion involved in playing at the Games.
However, each Emirati in the Games tour party will make their own decision individually, and some remain undecided.
Mohammed Abbas Darwish, the triple jumper, said he is unsure whether or not it will be feasible to fast and train with London's long summer daylight hours.
Like Al Derei, Mubarak Salem, the Emirati swimmer, will begin his fast after his competition ends.
"Mubarak won't fast during the Olympics," said Jay Benner, the UAE swimming coach.
"While in London he will prepare in a normal manner.
"After he finishes his competition, then he will observe the fasting. This is his decision I didn't have to approach him about it."
Worth, who will coordinate the nutrition of Jazira's players when their pre-season training officially begins this week, added: "… I have learnt from the Muslim staff I work with, who have always been really good in educating me on how things work.
"Part of that very much relates to the fact that if something is your work, or your dream - and the Olympics very much falls into that category - if it is something you have put all your effort in to, then religion is respectful of the fact this is what you are chosen to do.
"This is the plan for you, therefore it is acceptable for you to do your fasting at another time, so you can give yourself the best opportunity.
"It can be flexible to fit with modern life and it is personal."
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