The Keeping Up With The Kardashians star, 27, has been keeping a low profile in recent months, leading to speculation he's been seeking help to shift the pounds.
Not true, according to Rob.
In a flurry of tweets today, the reality star slammed claims he had attended "fat camp", saying he'd address his weight when he was ready to in his own time.
"So I found out I was trending for being fat," he tweeted. "Thank you all. It really made my day."
Rob later added: "To the blogs saying I went to fat camp or rehab. LOL. Then why am I still fat you fools? Y'all must have run out of real news."
He concluded: "First, I don't believe in rehab or therapy or anything of that sort, and second, I'm a grown man and will work on myself when I choose."
"I'm aware that I'm fat that def aint a surprise to me lol and my only therapy will be in the gym anyways had to say somethingggggggggg."
Rob's tweets come as he flies to Paris, France to attend sister Kim Kardashian's wedding to rapper Kanye West. The sock designer was pictured at the airport in Los Angeles on Sunday, preparing to board a plane with his mum Kris Jenner.
The photographs prompted a string of stories about his size and claims that he'll be flying his personal trainer to Paris to keep up his fitness regime while he's away.
Rob will be a guest at Kim and Kanye's wedding this weekend.
Last week, sister Kim posted two throwback pictures of Rob to her Instagram account, showing their brother-sister bond.
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