Keira Knightley's mother has slammed reports that her daughter has 'anorexia' - an eating disorder.
Sharman Macdonaldhas accused 'playground bullies' for persistent rumours about her the 23-year-old's waif-like figure.
Macdonald, a playwright, said that her daughter has a genetic predisposition not to put on weight, inherited from her father.
She said Knightley, best known for her roles in the Pirates of the Caribbean series, has been forced to adopt a diet high in protein and carbohydrates to make sure that she does not become too thin.
Like the actress' father, Will Knightley, a theatre actor, she must 'eat like a horse" to maintain a healthy body weight.
"She has always been thin. She's her daddy's daughter, with his long body," Times Online quoted Macdonald, as saying.
Macdonald revealed that the actress had been put on a tailored diet to bulk up for her role as Guinevere in the 2004 film 'King Arthur'.
However, she had been forced to abandon it because she was eating less than normal and was losing weight.
Knightley remained stick-thin, and her bust was digitally enhanced for American posters advertising the film.
While the Oscar-nominated actress has admitted that her grandmother and great-grandmother suffered from anorexia, she says she has not inherited it.
Macdonald said that the false accusations are distressing but felt helpless to stop them.
"It's a playground situation that we're looking at with the press - it's a form of bullying - but what can we do?" she said.