Kim Kardashian has proved that she never had butt implants but did the reality star have fat injected into her famous backside? On a 2011 episode of "Keeping Up With the Kardashians," the reality star had her derriere x-rayed to prove once and for all that she doesn't have butt implants.

Now, there are rumors that Kardashian underwent another type of procedure in order to obtain a rounder booty. According to British magazine Closer, a source close to the 33-year-old revealed that Kardashian had fat injected into her butt.

"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," the source said.

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

The procedure the reality TV star reportedly got done is called "buttock augmentation with fat grafting," the Daily Mail reports.

"She may have had fat injections before her pregnancy," plastic surgeon, Professor Laurence Kirwan told the Daily Mail. "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 necessarily disappear with weight loss."

Kardashian's booty has been making headlines recently when it was reported that she hired a "booty tailor." The new mom shelves out a reported $5,000 a day to have 23-year-old Cornelius Clay on-call to alter her pants whenever she needs it.

There were also rumors that Kanye West advised his bride-to-be to take out a $21 million insurance policy on her backside just in case... something happens to it.

"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 future. He got their broker to value Kim's bottom."