The Kardashian sisters are worried about being the "fattest" member of the family.

Khloé Kardashian

Khloé Kardashian

Following Khloé Kardashian's weight loss, her half-sisters Kylie and Kendall Jenner and sister Kourtney Kardashian are reportedly doing whatever they can to ensure they're not the "largest" sister.

A source told America's OK! magazine: "You'd think they'd be happy for Khloé after the hell she's been through, but Kendall, Kylie and even Kourtney are freaked about being 'the fattest Kardashian girl' now that Khloé's got things under control.

"The narcissism and body dysmorphia is unreal - if they're not starving themselves, they're on cleanses, going under the knife or squeezing into dangerous corsets."

Meanwhile, the 30-year-old television personality recently shared a picture of her amazing weight loss, revealing she had initially turned to exercise to help relieve stress.

Captioning a photo on Instagram, she wrote: "Looking back at pictures of myself I didn't realize at the time how unhealthy my lifestyle actually was. People love to call me the fat one but as weird as it sounds I still don't think I would consider myself fat back then. Definitely overweight and unhealthy, yes.

"About two years ago I decided to turn to fitness as a form of therapy and as a stress reliever. I started slow and eventually I started working out 4 to 5 days a week...

"Working out is a huge part of my life now. I genuinely enjoy sweating out my frustrations and living a healthier life. My workouts are not all about vanity. (sic)"