The super-thin Spice Girl - who will star as herself in the special episode of the hit comedy about a glossy fashion magazine - will shock audiences by turning up to the on screen wedding in a fat suit, pretending to have gorged on calorific treats since her move to America.An insider at the ABC network said: "Everybody at the wedding will be expecting skinny beautiful Posh to show up.
"But they'll be horrified to see she's piled on the pounds because of major comfort eating and American junk food."
The 33-year-old singer - who recently moved to Los Angeles with husband David Beckham and their three sons after he signed a multi-million dollar contract with the Los Angeles Galaxy soccer team - admitted she was not invited to appear on the show for her acting prowess.
She said: "I'll be playing myself. And I'll get to wear a fabulous outfit, so I won't be acting."
The mother-of-three is desperate to be a Stateside success and is hoping her appearance on the show will help raise her profile.
