Britney Spears is reportedly suffering from an eating disorder brought on by the pressure to deliver a perfect comeback.

The pop princess - who faces the UK's X Factor judges this Saturday - has resorted to regular throwing up sessions in a bid to stay slim, according to a US tabloid report.

A source close to Brit's bodyguard tells Star, "Britney's diet consists mostly of Taco Bell and turkey jerky washed down with Red Bull.

"She throws up after meals, both at home and at restaurants and she isn't very discreet about it.

"People around her think she's bulimic."

The singer is also said to be taking diet pills and laxatives to keep off the lbs.

Another insider reveals, "The pills are like diuretics. She has to go to the bathroom constantly.

"It just runs right through her. And everyone knows she still throws up when she's eaten too much. You can smell it in the bathroom."

See Brit's body through the years