The Reality of the Biggest Loser is on Netflix, find out why host Alison Sweeney left the show and what she does now.

Netflix's tell-all docuseries about 'The Biggest Loser' featured interviews with former contestants, trainer Bob Harper and more — but not Jillian Michaels

For those less familiar, let's take a look at who Jillian Michaels is and what she's been up to since the Biggest Loser wrapped – and what we know so far about her decision not to appear in the Netflix docuseries,

Michaels was a trainer on “The Biggest Loser” for seasons 1, 2, 4-11, 14, and 15. She often motivated contestants by yelling at them or insulting them. In one clip from “Fit for TV: The Reality of the Biggest Loser,” Michaels pushes a woman to keep exercising even after she vomits on a treadmill.

Rachel Frederickson won The Biggest Loser Season 15 in 2014 after losing a staggering 155 pounds, dropping from 260 pounds to just 105, meaning she’d shed nearly 60% of her body weight over the course of the competition. When she stepped on stage at the finale, viewers, fellow contestants, and even the show’s trainers appeared visibly stunned.

The Reality of The Biggest Loser' featured 'The Biggest Loser' host Alison Sweeney as she talked about her experience on the show.

Tracey Yukich tells Fox News Digital that she learned a lot about herself on the show. Yukich appears in the new Netflix documentary "Fit for TV: The Reality of the Biggest Loser."

Back in 2009, Danny Cahill won $250,000 after being crowned the winner of The Biggest Loser Season 8. He lost nearly 240 pounds on the show. Cahill started the show at 430 pounds and was down to 191 pounds by the end of his journey.