“WHAT in the world are you feeding O.J.?” Outraged Nevada prisons offi­cials demanded an answer to that question from the warden of Lovelock Correc­tional Center, where disgraced football legend O.J. SIMPSON has been imprisoned since 2008, an insider told The ENQUIRER.

Officials were so shocked at Simpson’s size during his recent televised court appearance, they immediately ordered a review of the pris­on’s menu.

TV viewers were also surprised when the 65-year-old athlete – tipping the scales at a humongous 300 pounds – shuffled into a Las Vegas courtroom on May 13 for a hearing to determine if he deserves a new trial for his armed robbery and kidnap­ping conviction.

AS THE ENQUIRER revealed in early April, O.J. has become ad­dicted to junk food that he buys in the prison commissary with money sent to him by adoring female fans.

But a published report says that the 6-foot-1 chow hound claimed he packed on the pounds by eating cans of pork and beans from the commissary – and that his bulk is “all muscle.”

He told friends his bingeing is part of a bodybuilding regimen where he loads up on beans and works out like crazy to convert fat into muscle.

“I gained weight eating all those beans, but just because I can’t get enough fruits and vegetables,” he reportedly told a friend. “My family’s been bugging me to stop with the beans.” The starchy prison meals are also a far cry from an ideal diet.

“The menu for breakfast is oatmeal or cream of wheat, hard-boiled eggs, hash browns and turkey sausage,” said the in­sider.

“Lunch is four pieces of bread, turkey salami, cheese and carrots or celery. Dinner includes lasagna once a month, baked chicken twice a month, and the rest of the time it’s hot dogs, hamburgers or corn dogs. Beef stroganoff is a once-a-month meal, and french fries are a regular side dish.”

To make matters worse, contrary to what he’s telling pals, the former running back rarely exercises.

“O.J. is involved in the softball program but doesn’t play,” revealed the insider. “He’s the umpire, sitting on his butt, barking at players and eat­ing ice cream.”