Jillian Leigh McKarus (born February 18, 1974), known professionally as Jillian Michaels, is an American fitness trainer, nutritionist, businesswoman, media personality, and author. She is best known for her appearances on NBC series such as The Biggest Loser. She has also made an appearance on the talk show The Doctors. In 2015, she hosted and co-judged a series on Spike titled Sweat, INC. In 2016, her reality television series Just Jillian premiered on E!.
Michaels was born Jillian Leigh McKarus in Los Angeles on February 18, 1974, the daughter of psychotherapist JoAnn and lawyer Douglas McKarus. Her mother is Jewish and her father is of Syrian and Lebanese descent from both of his parents' sides. She was raised in the Tarzana neighborhood of Los Angeles. She identifies as half Jewish and half Arab.
McKarus Anglicized spelling of the Arabic Christian name Makarios. Michaels' paternal great-grandfather's lineage traces back to the name Makarios Al-Ghuzz. According to immigration records from 1926, her paternal grandfather, Roger Essa McKarus, was born in Kfeir, Lebanon. He immigrated to the United States alongside his father—Jillian's great-grandfather—Essa McKarus, and his mother, Ruth, who were also born in Lebanon.
Michaels was overweight in her youth, using food to comfort herself, most pronouncedly at age 12 when her parents divorced, and topping out at 170 lbs. around the time she was 13. Her mother enrolled her in martial arts classes to help her deal with stress, which inspired her interest in exercise and fitness.
She attended California State University, Northridge, supporting herself as a bartender and personal trainer during that time. In 2002, after working briefly as an agent with International Creative Management, she opened the sports medicine facility Sky Sport & Spa in Beverly Hills.
As a personal trainer, Michaels uses a blend of strength training techniques with her clients, including kickboxing, yoga, Pilates, plyometrics, and weight training. Michaels has also developed a continuing education series for trainers with AFAA and holds a nutrition and wellness consultant certificate with the American Fitness Professionals and Associates (AFPA).
Jillian Michaels: The Fitness App is one of the top fitness apps globally and has won awards from both Apple and Google for best of in health and fitness app category. Michaels has also authored 9 books on health and wellness topics with eight New York Times Best Sellers New York Times Best Seller list.
Since February 2011, Michaels has hosted a weekly podcast, Keeping It Real, through iTunes. In December 2011, the show was among the podcasts honored by Apple in its App Store Rewind 2011, winning in the Best New Audio Podcast category. Michaels recently formed a partnership with Bill Maher's Club Random to expand her audio podcast "Keeping It Real" to video.
Also in the same year, Michaels appeared in a commercial with former race car driver Danica Patrick for the Internet domain website godaddy.com for Super Bowl XLV.
Michaels launched her company, Empowered Media LLC, in 2008 and released her fitness video membership website called Fitfusion.com. Fitfusion is also associated and broadcasts on AT&T U-verse, BroadbandTV Corp, Bell Satellite TV Canada, and other TV channels, as well as Roku, Apple TV, and Fitness OnDemand reaching audiences in Marriott, Hilton Worldwide and Shangri-La Hotels and Resorts.
In 2025, Michaels co-hosted Her Take, an online talk show with an all-woman cast that includes Ana Kasparian and Lindy Li. However, in late September, Michaels walked off the set and quit the show after getting into a heated debate about Israel, Benjamin Netanyahu, and the assassination of Charlie Kirk.
Michaels was a trainer on the reality series The Biggest Loser when the show started in October 2004. On the show, she assumed the role of Red Team trainer and remained in that capacity for the first two seasons. After her departure in 2006, she was replaced by Kim Lyons. She returned to the show in 2007 as the Black Team trainer competing against Lyons's Red Team and Bob Harper's Blue Team. Along with Harper, Michaels was also a trainer in the Australian version of the show from 2006 to 2008.
On December 7, 2010, Michaels announced via Twitter that the eleventh season of the show would be her last. Michaels made her last appearance on The Biggest Loser on May 24, 2011.
On September 4, 2012, it was announced that Michaels would return to The Biggest Loser in Season 14. Michaels also returned for Season 15, which premiered on October 15, 2013, on NBC, but did not return for Season 16 which aired in the fall of 2014.
On June 1, 2010, NBC debuted Losing It with Jillian, a spin-off of The Biggest Loser. In the show, Michaels visits the homes and workplaces of family members for a week.
Losing It with Jillian originally ran on NBC in June and July 2010. As of January 2012, all eight episodes of the series are available for viewing online.
Contract with CBS Television Distribution
On May 6, 2011, CBS Television Distribution announced that Michaels had signed a multi-year deal to become a co-host of the panel-discussion show The Doctors, as well as to serve as a special correspondent on the CTD program Dr. Phil. Michaels had been a guest on The Doctors several times previously. On the show, Michaels hosted a recurring segment called Ask Jillian, which dealt primarily with nutrition and diet topics.