Britney Spears is said to be on a crash diet in a bid to lose weight for her X Factor appearance this Saturday.

Britney has already lost two stone in recent months but wants to lose even more in advance of this weeks UK comeback.

A source told the Daily Star: “She goes to bed hungry and is dieting so hard she’s suffering from insomnia, anxiety, flushes and shakes.

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