London, Nov 26 : Popstar Britney Spears is keen to shed weight before her ‘X Factor’ performance – and so has reportedly gone on a crash diet.

The ‘Hit Me Baby One More Time’ hitmaker is so desperate to look sexy for the X-rated performance that she’s reportedly gone on an unhealthy diet.

“She goes to bed hungry and is dieting so hard she’s suffering from insomnia, anxiety, flushes and shakes,” The Daily Star quoted a source, as saying.

“Her father and the people around her are trying to get her to eat more, but Britney is determined not to be criticized for having any extra bulk,” the source added.

Britney, who has already shed two stones, wants to get rid of 7 stones in a bid to outshine Chery Cole and Danni Minogue.

The 26-year-old popstar became paranoid about acquiring a toned body after appearing on stage with Madonna last month, saying clips she saw made her look “beefy”.

The mum-of-two tells Rolling Stone mag: “I feel like an old person. I go to bed at 9.30 and I don’t go out.” (ANI)