After Tweeting her annoyance at media outlets who reported she had gained weight, Kelly decided to prove she hadn't with the defiant Instagram picture.
"When did I all of a sudden gain 20lbs?" Posted Kelly. "I just asked my ass and she can't seem to remember either! #MustBeASlowNewsWeek!"
While Kelly's post was directed at those reporting a weight gain, several of her fans proved they had believed the rumours, telling her to keep focussed and work hard to loose the extra pounds.
"That was meant to be a joke people," she later clarified. "I have not gained 20lbs!"
Cara Delevingne and Kelly Osbourne wear matching tattoos
The tweet was clearly not enough to prove Kelly point and she later posted a picture of her toned stomach with the caption: "#20PoundsRight? I think not!"
The picture shows Sharon and Ozzy Osbourne's daughter sporting a lime green jumper and skirt. While the picture doesn't show the Fashion Police presenter's face, she can be seen holding her jumper up to reveal her stomach.
Kelly Osbourne's style transformation
Several magazines had reported that Kelly had gained weight in the weeks following her split from fiancé Matthew Mosshart.
Kelly and Matthew
The pair announced in January that they were ending their relationship after two years together.
"Kelly and Matthew have decided to end their engagement," read a statement from the couple. "The split is amicable and the pair continue to have nothing but the utmost respect for one another."
"Kelly is looking forward to a new year full of fresh beginnings. No further comments will be provided by all parties and we request privacy, decorum and space from the press but don't expect it."