The 40-year-old personal trainer has officially quit the show, and does not appear on the program's upcoming 16th season.
"After helping hundreds of contestants transform their lives and inspiring millions of viewers at home, The Biggest Loser and Jillian Michaels have decided to part ways," NBC said in a statement. "She will not be returning for season 16 when it airs in the fall."
Michaels trained contestants on 12 of the show's 15 seasons. She was temporarily replaced by Kim Lyons in season 3, and officially left for seasons 12 and 13. Her departure now appears to be permanent, according to reports earlier this year.
"She's deeply concerned about the direction the show has been taking," a source told People in April. "She is turned off by the mean-spirited story lines and poor care of the contestants."
The "poor care" mentioned includes the treatment of season 15 winner Rachel Frederickson. Michaels was not the champion's assigned trainer, and was visibly stunned when the contestant appeared on the show's finale weighing only 105 lbs.
"Michaels wants to distance herself from the Biggest Loser brand, especially considering what happened with Rachel," the source elaborated. "Her feeling is that there isn't proper attention paid to the contestants' health or wellness."
"The show uses her as a bad guy, and anyone who knows Jillian knows she's not the bad guy at all," the insider continued. "She's a loving mother of two kids. She's not the negative person they portray her as. She wants to be in a place where she has more respect."
Season 16 of The Biggest Loser premieres September 11 at 8 p.m. on NBC. The network has not yet announced a replacement.