The biggest religious challenge for the London Olympics is Ramadan – Islam's annual month-long fast, which occurs this year in the middle of the international games. Devout Muslims do not allow anything – even chewing gum or breath spray – to pass their lips from sunrise until sunset for 40 days. Each evening, they can break the fast – and do with much festivity. However, this is a tough challenge for a long-distance runner who needs to be drinking as much water as possible. Observing Ramadan could put Islamic athletes at risk or at least at an extreme disadvantage in the summer’s heat.