The my life would suck without you singer loves being a role model for curvy girls, and is especially proud of her shapely posterior.

She said: "I totally have no chest, I'm all butt. Ever since I was a kid I've had a bubble butt - I get it from my mama. Guys are usually like, 'Oh my gosh, look at that butt!' In a good way!

"I'm a fan of my butt. I like filling out a pair of jeans, because sometimes I see girls who can't and I feel bad about that."

Kelly, 27, has been criticised for her fluctuating weight, but insists comments about her figure do not bother her.

She is happy to admit she has cellulite and struggles to stay slim, and claims women who say it is easy to stay in shape are lying.

She told Britain's Heat magazine: "Dude, every woman has cellulite, I don't care who you are. Unless you're some anorexic girl in some mental institution - but even then their skin gets like that and worse. Any girl who tells you she doesn't have cellulite is a frickin' liar!"

Although Kelly has ruled out having cosmetic surgery to improve her figure, she is adamant women should not be lambasted if they do go under the knife.

She insisted: "If a girl wanted bigger boobs, she could get them, but you can't get a bigger butt!

"I'm kind of on the fence about it, because I have a friend who was completely unhappy with her boyish figure and she got breast implants and it turned her life around. So it's hard for me to be against it, but I'm also not for it. I would never do it."