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The "Biggest Loser" doesn't take well to contestants quitting -- but what about trainers? Famed fitness guru Jillian Michaels, who left the show once before in 2011, wants to quit the show again, a source tells Us Weekly.

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Michaels, 40, "regrets" her 2013 return to the weight-loss competition, the insider says. "They paint her to be an a--hole. She's the only woman trainer, and she gets a bad rap," the source tells Us. "She's sick of being painted as the bad guy."

The source adds: "Everyone who knows Jillian knows she is the sweetest woman. No one can ever say a bad word about her. She's nice, calm, and so sure of herself."

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Michaels, a mom of two, was one of the original trainers on "The Biggest Loser" when the show debuted in 2004. With the exception of a brief break in 2006, she was a steady presence on the series until 2011, when she left to "focus on becoming a mommy and doing more charity work," she said via Twitter. Two years later, she returned for the competition's 14th season.

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Now, having just finished filming the controversial 15th season -- during which winner Rachel Frederickson shrunk to a tiny 105 pounds, shocking Michaels, fellow trainer Bob Harper, and millions of at-home viewers -- the "Losing It With Jillian" alum wants out.

Michaels' rep Leslie Sloane had no comment.


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