The UK edition of Grazia magazine has admitted it slimmed the waist of Kate Middleton by digitally altering a cover image of her on her wedding day.

In its 9 May edition the weekly fashion title published a photograph of what appeared to be an impossibly thin Duchess of Cambridge standing alone in her bridal gown.

Digital diet ... Grazia admits to "inadvertently" slimming Kate Middleton's waist.

The image has reignited the debate over the use of digital manipulation in women's magazines.

After investigating a complaint to the press watchdog that the image had been manipulated, the Bauer Media-owned magazine has conceded that it doctored the original image of William and Kate leaving Westminster cathedral.