American Airlines chief executive Doug Parker fasted for one day during the Muslim holy month of Ramadan.

Parker received an invitation to fast from the company's Muslim Employee Business Resource Group (EBRG), which invited non-Muslims at American Airlines to fast for unity on April 29.

"I can tell you I was hungry — and really thirsty — by 8:30 at night. It gave me tremendous respect for our Muslim team members and their commitment to their faith," Parker wrote in his LinkedIn post.

"I am proud of the work our Muslim EBRG does for American Airlines and we all thank them for their leadership and their open invitation to connect as humans," he added.

Muslims must abstain from all eating, drinking or smoking from dawn to dusk each day for the entire lunar month, around 30 days. A single sip of water or coffee, or a puff of a cigarette, is enough to invalidate the fast.

Fasting is meant to bring worshippers closer to God through steady remembrance, reflection and sacrifice. Daily fasting, combined with five daily prayers and extended evening prayers, challenges worshippers to focus on their actions, deeds and thoughts, rather than on material desires and instant gratification.