FORMER Hollywood wild child KELLY OSBOURNE has slimmed down to an itsy-bitsy size 1 – thanks to falling in love with a vegan chef!

Sources say the 5-foot-2 co-host of E! channel’s “Fashion Police” once weighed a porky 160 pounds. But now she’s 60 pounds lighter and excitedly planning her spring wedding to fellow Brit Matthew Mosshart.

“Kelly’s battled a weight problem all her life,” said the source. “She was a junk food junkie who loved fish and chips, greasy burgers, pasta, meat and cheese. But three years ago, she got serious about losing weight.

“Since then, she’s dropped a total of 60 pounds, and the final 15 came off after she and Matt became a couple.”

Matt, 29, an accomplished vegan chef, has taken over his 28-year-old sweetie’s kitchen, added the source.

“He prepares smaller meals of grilled vegetables, fruit, grains, nuts and seeds for Kelly,” said the source. “And he makes sure they work out together at least five days a week.”

In the past, Kelly – the daughter of heavy metal rocker Ozzy and his wife, “The Talk” co-host Sharon – saw her weight fluctuate while she bounced in and out of rehab.

“Kelly says it’s easy to pass up junk food now because she has the reward of looking good,” said the source. “Besides that, she adores the fact that Matt helped make her dream of losing weight come true.

“He’s her idea of the perfect man, and Kelly’s looking for the perfect wedding dress to show off her new figure.”