Gillian McKeith has threatened to pull out of the Celebrity X Factor competition.

The TV diet expert was furious after learning that show judge Louis Walsh had claimed that she "looked like a bus" and accused her of having a "huge ego".

A source told the Sunday Mirror, "Gillian feels she is being judged even before the show begins. Despite what people see of her on her own TV programme, she is very nervous about singing live to millions of viewers. The only reason she agreed to do it was to raise money for charity.

"Now she's even considering whether it's worth doing the show at all if this is a taste of things to come."

The series begins on May 29 on ITV1.