Now that Kelly Osbourne is a "true fashionista" on E!'s Fashion Police, she's comfortable dissing other celebs for their weight. Hmm.

During a recent taping, Ms. Osbourne, 26, claimed Xtina was "stuffed into" her black gown while promoting her latest fragrance. Kelly added:

    "Maybe she is just becoming the fat b**ch she was born to be. I don't know. She was a c**t to me."

Find out why Kelly felt the need to say this on the show ... after the jump.