The Islamic State group has prohibited its members from eating more than once a day as it deals with food shortages in Iraq. ISIS leaders have also told militants that keeping fast puts them closer to the Prophet Muhammad, according to local media reports.

The food shortages have unfolded as ISIS fights off the Iraqi army and a U.S.-led coalition moving to liberate the city of Mosul from the militant group. As the battle enters its second week, ISIS' biggest storage facility has already been destroyed by airstrikes, limiting the group's food supply. 

While Islamic State leaders have urged Mosul residents to donate food to the cause, they've also sought to encourage rank members by comparing the food crisis to a food embargo forced on Muslims during the earliest days of Islam under Prophet Muhammad.

Hunger isn't unusual in Iraq. Roughly 4.4 million Iraqis required U.N. assistance last year, and about 30 percent lived below the poverty line.

But for ISIS, these are especially lean times. At one point, the militant group controlled 40 percent of Iraq’s annual production of wheat, a crucial food staple in the impoverished nation. Anyone who resisted the group's advances was denied food back then, sending food prices soaring.

"They distribute flour to the Arabs in the area. They get the wheat from the Hawija silo ... And they run the mill and they distribute to people in a very organized way," Ahsan Moheree, chairman of the government-affiliated Arab Farmers Union in Hawija, told Reuters in 2014. 

ISIS seized Mosul that year, imposing its strict version of Islamic law that passes down punishments such as beatings and death for offenses including smoking and shaving beards. About a million people live in Mosul, including 5,000 ISIS fighters.