Kelly Osbourne Talks Body Confidence & Feud With Christina Aguilera (PHOTOS)

Kelly Osbourne lost a lot of weight a few years back, posed in a bikini on the cover of a magazine to show off her hard work and has managed to keep the weight off. But years of comments from everyone from childhood bullies to high profile celebrities have left her struggling to be confident with her body, even now that she's at a healthy weight.

"I call myself an FFP: former fat person," the "Fashion Police" co-host writes in Glamour's May issue . "And when you're an FFP, you will always see in yourself what people used to bully you for."

Growing up on the road with rockstar dad Ozzy Osbourne didn't shield Kelly from bullies, who called her "Kelly Smelly With the Big Belly Whose Dad's on the Telly," and left emotional scars.

"Even now I don't consider myself skinny," she writes. "But I have put a lot of hard work into my body over the years, and in the process, I've really learned to love myself."

The 27-year-old struggles like all of us, but she offers some tips to Glamour readers to help boost their body confidence.

First, it's important not to wish you looked like someone else and focus on the things you like about yourself, she says. "We dont recognize our own beauty because were too busy comparing ourselves to other people. No, we are not all Gisele Bndchen; were not all Beyonc."

Osbourne says that it's important to ignore the "judgy voices," -- yours or critics'. The former reality TV star cites her ongoing feud with Christina Aguilera as a voice she had to just "shut out." While discussing the singer's weight gain on an episode of the show , Kelly bluntly said, "She called me fat for so many f***ing years. So you know what? F**k you! You're fat too."

It's a comment Kelly says she stands by. "I didn't say I wasn't fat. I said, 'Now you know how it feels,'" she explained, adding that she makes a point on "Fashion Police" not to say anything about anyone she wouldn't say to their face.

"I'm famous, and she's famous; it doesn't mean I can't stand up for myself. I took it for 10 years and decided to be like, 'You know what? I'm done,'" she wrote and added that it's the last thing she's ever going to say about their feud.

For more body confidence tips from Kelly Osbourne, click over to Glamour .

Check out Kelly's ever-changing look throughout the years: