It is not clear whether Williams will break his fast when the Blues take on the Reds in Apia, Samoa next Friday. The most essential item that is off the list, should he choose not to break his fast, is water.
Williams also took to Twitter stating that he was looking forward to the start of Ramadan.
"May the most high bless all the brothers and sisters in this blessed month," he wrote.
The father of two daughters, Imaan and Aisha, converted to Islam in 2008.
He said sacrificing food and water for Ramadan allowed him to step out of his comfort zone.
Ramadan is intended to draw the faithful closer to Allah, control their desires and remind them of the suffering of the less fortunate.
Fasting during Ramadan is one of the five pillars of Islam along with faith, prayer, charity and making a pilgrimage to Mecca.
Ramadan began today and will run for a month.
Muslims in New Zealand will fast for just about 11 hours a day thanks to the holy month running over our shortest winter days.