It's been more than two years since I last wrote about Kelly Osbourne and the dramatic health makeover that led to her landing the cover of Shape magazine. Back then, Osbourne credited her 50-pound weight loss to simple diet and exercise. 

"I used to eat chips and cookies and drink soda all day long," she told Shape. "I had to start making better choices. Now, when I'm full I stop eating!"

While competing on ABC's reality series "Dancing with the Stars" in 2009, Osbourne says her dancing partner Louis van Amstel pointed her diet in the right direction. 

"He made me eat turkey burgers and salads and explained to me that a high-protein, low-carb diet would keep me energized," she said. "Then I started losing weight and realized, 'Oh, it's true what they say: Diet and exercise really work!'"

Fast forward to today and Osbourne is an additional 19 pounds lighter, with the latest health push all thanks to her new vegan chef boyfriend, Matthew Mosshart. 

"Over the past two years, I've lost over four-and-a-half stone — but I've only lost the last stone since I met Matthew," she tells the Daily Mail. "That's because he cooks for me! He's a vegan chef, so he makes sure that I eat healthily."

The 28-year-old "X-Factor" co-host now eats a diet rich in vegetables, fruit, nuts and seeds — and also regular exercise. 

"I'm happy with how I look now," she tells the site. "As long as I'm healthy, do exercise and eat right, that's the main thing. I'm slim now, but I don't want to be anorexic. I love Matthew and we love to work out together — we motivate one another. 

Posing in several bikinis in the latest issues of Cosmopolitian Body UK, Osbourne adds that her transformation has all been hard work — but completely worth the effort. 

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

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Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Kelly Osbourne's weight loss secret: Vegan chef boyfriend
Former reality star says she's lost more than 69 pounds thanks to exercise, diet and a bit of help from her vegan chef beau.