"The Biggest Loser" may be about to incur its own serious weight loss.

Trainer Jillian Michaels is ready to leave the hit NBC show, following Season 15 winner Rachel Frederickson's controversial 155-pound weight loss, a source reportedly told to E! News. It wouldn't be the first time Michaels' left from the series, as she returned for Season 14 after departing two seasons earlier.

"Nothing is official yet, but Jillian has said she wants off TBL," the source reportedly said. "She wasn't happy with how last season went. The shocking weight loss of Rachel (Frederickson) doesn't do the brand any favors and she wants to distance her name from it."

Michaels, 40, reportedly also wasn't pleased with how the show handled the controversy concerning her giving contestants caffeine supplements without doctor's permission, which was technically against the rules.

Michaels stood by her decision, hinting the fallout (her team received a four-point disadvantage and Ruben Studdard was allowed back into the competition) was a ratings ploy.

E!'s source reportedly said Michaels "did not appreciate how the caffeine pill controversy went down. She felt like they threw her under the bus."

So ... she technically cheated, got caught, suffered consequences, and blamed someone else?

No wonder she's thinking about quitting. Don't they know this is America?

Though she was silent about Frederickson's shocking weight loss right after the finale, Michaels (who wasn't her trainer) admitted in February she "was stunned" and questioned the show's "checks and balances."

"We are allowed to speak with our contestants after they go home ... but no one had told me, 'Hey, Rachel is very, very thin.' Bob (Harper) and I had no idea. Nobody had told us, nobody had said anything to us, so yes, I was stunned," Michaels told HuffPost Live. "Obviously, I thought she had lost too much weight, and I was immediately concerned and wondering how this happened, how no one had said something to me and how the checks and balances that have been put into place, in my opinion, this had fallen through those checks and balances."

After Frederickson's situation made headlines, a source reportedly told E! News the show was considering "small but significant tweaks" for the new season. "There might be more focus on what happens to the winner after they are supposedly done with the show," the insider said.

NBC had no comment on Michaels' possible exit from the series.

Contact Tony Hicks at Facebook.com/BayAreaNewsGroup.TonyHicks or Twitter.com/insertfoot.