Kendall Jenner has made a name for herself as the undisputed model of the moment and with that comes her lean and long physique. 

While her famous sisters (we're looking at you Kim and Khloe) endlessly champion their killer curves, the 19-year-old Keeping Up With The Kardashian's star's body type is a homage to her more athletic roots. With legs up to here, long toned arms, a strong torso and, you know, a mind-blowingly gorgeous face, she's fast become one of the most in-demand girls on the runway as well as behind the lens on mega campaigns.

So, you'll totally get how gobsmacked we were when we clocked this latest pic of Kendall with a notably more, err, fuller butt — something she definitely didn't have before! 

Taking to her Instagram to share the saucy shot, Kendall simply captioned her pic 'Denim Days', completely ignoring the main feature of the shot. Rocking a pair of Calvin Klein pants and jeans — she is the brand's face after all — she can be seen perching on the edge of her bed while topless with an effect clearly warping the pic, contributing to her bum's fuller appearance. But it's not all smoke and mirrors... 

Where DID that butt come from, Kendall Jenner?!

It's not the first time Kendall has given us a glimpse of her newly pert derriere. Wearing a pair of white jeans so tight they could be spray-on, the starlet posted this raunchy pic to her Insta-account just a couple of weeks ago where she can be seen leaning onto the back of a chair to clearly emphasise her asset. Yep, this girl's got posing for the camera down. 

Unsurprisingly, Kendall's fuller and seriously perky butt has sent her 22 million-strong following into a bit of a tizzy. Has she been hiding her bum from us all along? Is it an exemplary case of body-bending?

Or — as some of her fans are suggesting — has she employed the use of bum-enhancing pants [yep, they're an actual thing]? We kind of have our own theory on the matter... 

We asked top celeb personal trainer and founder of Christina Howells for her thoughts on the matter and she thinks that Kendall could have achieved these very impressive results thanks to her vigorous workout routine — but don't be fooled, it doesn't happen over-night.

Christina says: 'To lift your butt you need to create definition between the gluts and the muscles of the back of the legs, so you need to train your hamstrings as well. Make sure you include deadlifts, hip lifts, squats, backward lunges and ankle weight butt moves. Lift as heavy as you can for 12-15 reps. If you don't have weights at home, try doing 50 squats whilst you clean your teeth!'

So, there you have it — if you want a butt that's as gravity-defying as Kendall, copious amounts of squats and maximising your teeth-cleaning regime are the answer. 

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Excuse us while we stock up on toothpaste and weights, pronto!