The 33-year-old reality star took to Twitter following the publication of a story in Life & Style magazine titled "Weight-Loss cheater".
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The article claimed that Kim did not lose weight by going on the Atkins Diet, but rather by undergoing secret cosmetic procedures at a clinic in Beverly Hills, including stretch-mark treatments and a fat-reducing ultrasound on her stomach.
Kim used her Twitter account to set the record straight. "I am very frustrated today at seeing reports that I got surgery to lose my baby weight, " she wrote in a lengthy post on Wednesday. "This is FALSE.
"I worked so hard to train myself to eat right & healthy, I work out so hard & this was such a challenge for me but I did it!!
"I'm so proud of my accomplishment & NO ONE will take this away from me with fake reports! Say what u want about me but I work hard & am the most disciplined person u will ever meet!"
This latest insult comes after Kim endured months of criticism about her figure during her pregnancy.
In an interview with Jay Leno last month, she proudly revealed she had lost 50 pounds since giving birth to baby North West in June.
She credited the Atkins Diet and exercise with her success, and admitted that the criticism directed at her weight while she was pregnant "really did affect" her.
"It really hurt my soul," she said. "There were these stories where I was, like, 200 pounds. I was gaining weight because I was pregnant and it was really hard to read all these stories and hear all these nasty things."
Since then, the mum-of-one has been celebrating her post-baby body; from her revealing swimsuit selfie to her near-naked appearance in fiancé Kanye West's music video Bound 2.
"Kim's body is so insane," her younger sister Khloé Kardashian recently told Australian radio station Fox 101.9.
"It's always been beautiful, and then she got so much scrutiny, and just people were so disgusting to her when she was pregnant.
"I don't care if you weren't pregnant. If you're a bigger girl, God bless you! Who cares? It's no one else's business and then for you to criticise someone when they are pregnant is so disgusting and disturbing to me.
"So now that her body looks like this, it's a major middle finger to the world. And, honey, she deserves it!" she added.