The Fashion Police co-host laughed off the speculation via Twitter on Thursday night (3 April), joking no one had told her about her supposed plight.
Kelly tweeted: "When did I all of a sudden gain 20lbs? I just asked my ass & she can't seem to remember either! #MustBeASlowNewsWeek!
"That was meant to be a joke people I have Not gained 20lbs!"
And, just to prove her point, the starlet tweeted a picture of herself holding up her jumper to show off a trim waist.
Kelly hasn't let the weight speculation dampen her week, however. After clearing up the rumours, she quickly turned her attention to work, excitedly telling her Twitter followers about a new Disney project she's working on.
The Osbournes star is voicing a character called Hildy in a new Disney Channel cartoon, but kept mum on any other details.
"I've now come to think of as my alter ego – she is my Sasha Fierce. The role has taught me so much about acting – and Hildy's a tough one to keep up with, so I wear workout clothes to recording sessions because I jump and move around to really bring her to life."
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