Is Britney Spears crash dieting for her "X Factor" performance?

It's true! British tabloids are reporting the pop star is looking to immediately lose about 10 lbs. that the camera adds. The Daily Star says Brit "wants to be super-slim before the show this weekend."

A source also tells the paper, "She goes to bed hungry and is dieting so hard she's suffering from insomnia, anxiety, flushes and shakes."