PHOTOS: The feud between Xtina and Kelly O. continues after Kelly criticizes Christina’s pantless ensemble at the Michael Jackson tribute concert, claiming she was “never that fat.” THE FAT FEUD IS BACK ON BETWEEN KELLY OSBOURNE AND CHRSTINA AGUILERA, AND BOY DOES KELLY HOLD ONE SERIOUS GRUDGE… KELLY AND CHRISTINAS INFAMOUS WAR ON WEIGHT GOES ALL THE WAY BACK TO 2003 WHEN THEY TOOK TURNS SLAMMING EACH OTHER AT THE MTV EUROPE MUSIC AWARDS NOW THE PAIR IS AT IT AGAIN… JUST ONE MONTH AFTER THE NOW- SVELTE STAR CALLED CHRISTINA A FAT B****, KELLY’S TAKING ANOTHER STAB AT THE SINGERS WEIGHT GAIN… SHE AND HER E FASHION POLICE CO-HOSTS WERE CRITICIZING CHRISTINA’S PANTLESS ENSEMBLE FROM MICHAEL JACKSON’S TRIBUTE CONCERT LAST WEEK. WHEN KELLY SAID, “She called me fat for years, I was never that fat.” WHILE GEORGE KOTSIOPOULOUS THOUGHT CHRISTINA DID PUT ON WEIGHT, HE BLAMED THE FASHION FAIL ON THE OUTFIT ITSELF, AND GUESSED SHE STILL WAS PROBABLY A SIZE 2 OR 4. BUT KELLY QUICKLY PUT IN HER TWO CENTS ADDING “Trust me. I’m a 2/4. That is not a 2/4.” YOUR MOVE, CHRISTINA….