Kelly Osbourne: ‘I couldn’t even do one sit-up!’

The Fashion Police presenter says she’s done with fad diets and that being healthy is a lifestyle change

Kelly Osbourne has opened up about her lack of fitness ability before she embarked on a healthier lifestyle.

The Fashion Police presenter admitted she could barely do ab exercises before she started working out.

Kelly Osbourne admitted she once couldn't do a sit-up © Cosmopolitan Body / Photographer Nicky Johnston“When I started exercising I couldn’t even do one sit-up! By the end of the first week I could do three, and that was a big deal,” she told Cosmopolitan Body magazine.

[Related: Kelly Osbourne: My weight loss secret is happiness]

“Now I work out every day and I just don’t feel good if I miss it. It’s amazing how quickly your fitness builds, but you have to really want it.”

In one shot for the magazine, Kelly is seen in a brown and blue striped bikini sporting an enviable cleavage, toned arms and a slim upper torso.

But Kelly's body transformation is evident in the full-body shot, where she's wearing a ruffled pink bikini and showing off her toned stomach and muscular thighs.

Kelly dropped five dress sizes on Dancing with the Stars © Cosmopolitan Body / Photographer Nicky JohnstonThe 23-year-old, who dropped five dress sizes on Dancing with the Stars in 2009, admits working out is a chore – but it’s worth it.

[Related: Kelly Osbourne wins Style Icon at Cosmo Awards]

“Working out is not fun, I’m not going to lie and say it is. I sweat my arse off and I’m miserable for the hour I’m doing it but when I’m done, I feel amazing,” she revealed.

“There’s no quick fix and it does take a long time. It drives you mad when you see someone eating chips when you can’t have any, but it’s so worth it.”

Cosmopolitan Body out Dec 27thBut for Kelly, being healthy is a lifestyle change and she says done with fad diets.

 “If you want to change your body you can’t just diet; if you do that, you lose weight, then get fat,” she said.

“You’ve got to commit to a whole life change and teach yourself a whole new lifestyle.

“It isn’t fun, but it never will be. I don’t deny myself anything – I still eat chocolate and cake and always will. Everything in moderation.”

What are your diet and fitness tips? Let us know over on Twitter now.

Full interview appears in new issue of Cosmopolitan Body, on sale Thursday 27 December 2012. Also available as a digital edition.