Did Kim Kardashian inject fat into her $21 Million butt?

An X-ray might have proved that she hasn't had implants, but that doesn't mean Kim Kardashian didn't get surgical help to make her derriere the most famous in the world.

Rumours have reignited over the question of Kim's ultra-curvy behind, as a source close to the star revealed that she has had fat from her stomach and thighs injected into her bottom to make it bigger than ever.

An insider told Closer magazine: 'Kim hasn't had implants. She's had the fat from her tummy and thighs taken out by lipo, then injected into her bottom. She also wears padded knickers sometimes.'

5ft 2 Kim gained 3.5 stone during her pregnancy with daughter North 'Nori' West, and lost the majority of the weight through the Atkins diet in the nine months since the birth.

The source added: 'She's always been obsessed with her bottom, and friends think she has had a top-up treatment on it since giving birth. On a good day she loves her bum and boobs, but some days she wishes she was taller and slimmer.'

The process of injecting fat from the body into the bum is called buttock augmentation with fat grafting.

This type of procedure is preferred by most surgeons and patients, as it creates a more natural look and feel compared to silicon implants, which can often be more painful and complicated to fit.

She may have had fat injections before her pregnancy,’ plastic surgeon, Professor Laurence Kirwan told MailOnline, ‘but usually when you lose a lot of weight the fat in the buttocks would shrink down too. Most bottoms shaped like Kim’s have had the procedure done, and if fat is injected artificially, it doesn’t necessary disappear with weight loss.’

He added: ‘Buttock enhancement is becoming the rage where there is a strong South American and African American influence especially in places like Miami. It’s good to focus more on these type of behinds than those of models, but it’s gone away from having surgery to make a bottom aesthetically beautifully, but rather how big it can be.’

Mr Miles Berry of Cosmetic Surgery Partners comments: 'It is a possibility that Kim could have had a fat transfer or fillers, there is a noticeable asymmetry to her bottom now with the right cheek being larger than the left which suggests a change from earlier years.'

'Alternatively, she could have had a cosmetic procedure and these could well be dressings that give an overall effect of global bulkiness, or she could just be wearing fat pants.'

No doubt Kanye wouldn't be impressed if Kim goes under the knife again, following the death of his mother from heart disease in 2007, 24 hours after she received cosmetic surgery.

His fiancée has publicly stated that she hasn't had 'butt implants' and filmed herself in 2011 getting an X-ray at a medical office, to prove no silicon was in her bum. 

However, the Keeping Up With The Kardashian star has admitted to having a 'bum tailor', who is paid to resize her clothes to fit her rounder than average behind.

It's no wonder then that Kim and her rapper fiancé believe it is her most prized asset, and have reportedly taken out an insurance policy on her bum for a whopping $21 million.

'People have always been obsessed with Kim's bottom,' a source told Grazia. 'Kanye encouraged her to take out the policy to safeguard it in the future. He got their broker to value Kim's bottom.

'Various factors were taken into account, including how much of her work is based on her behind and how it would be impacted if it were to be damaged.'