NBC has revealed the identities of the 18 contestants that will compete on The Biggest Loser's fourth season, which will premiere with a two-hour special on Tuesday, September 11 at 8PM ET/PT.

The 18 weight-loss hopefuls range in age from 24- to 62-years-old -- which means that the fourth-season cast will include The Biggest Loser's oldest contestant ever.  The Biggest Loser 4's cast also includes a Hurricane Katrina survivor from Louisiana as well as a set of twins from Long Island, NY.

The Biggest Loser 4 features several changes, including new host Allison Sweeney; a new "back to basics" concept that will take the show away from The Biggest Loser ranch; as well as the return of former trainer Jillian Michaels, who was replaced by Kim Lyons for the show's third season but will return, along with Lyons and original trainer Bob Harper.

During The Biggest Loser 4's premiere broadcast, a "surprising new twist" that will result in Lyons taking control of the traditional Red Team, Harper helming the traditional Blue Team, and Michaels training a new "secret" Black Team of contestants that had failed to be chosen for the other two trainers' squads will be revealed to the cast.  Despite the changes, the contestants will still compete in challenges and weigh-ins in an attempt to survive enough eliminations and claim the show's $250,000 grand prize.

On Tuesday, September 4 at 8PM ET/PT, NBC will air a one-hour The Biggest Loser: Where Are They Now? special that will give viewers an opportunity to see the progress -- or lack thereof -- that some of the show's previous contestants have made. 

The Biggest Loser 4's two-hour premiere on September 11 will be followed by another two-hour installment on September 18 before airing 90-minute episodes every week beginning Tuesday, September 25 at 8PM ET/PT.

The 18 contestants competing on The Biggest Loser 4 -- as well as their NBC-supplied bios -- are:

- Lezlye Donahue, a 34-year-old from Metairie, LA

- Bill Germanakos, a 40-year-old from Long Island, NY

- Jim Germanakos, a 40-year-old from Long Island, NY

- Patty Gonzalez, a 34-year-old from San Diego, CA

- David Griffin, a 31-year-old from Cedar Hill, TN
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- Julie Hadden, a 34-year-old from Jacksonville, FL

- Phil Hawk, a 27-year-old from Powell, OH

- Jerry Lisenby, a 62-year-old from Peoria, IL

- Jez Luckett, a 24-year-old from Garden City, KS

- Nicole Michalik, a 26-year-old from Philadelphia, PA

- Isabeau Miller, a 21-year-old from Franklin, TN

- Ryan Rodriguez, a 29-year-old from Jackson Heights, NY

- Hollie Self, a 28-year-old from Phoenix, AZ

- Neil Tejwani, a 25-year-old from Marblehead, MA

- Amber Walker, a 30-year-old from Houston, TX

- Bryan Washington, a 29-year-old from Riverdale, GA

- Kae Whang, a 27-year-old from Clark, NJ

- Amy Zimmer, a 28-year-old from Rochester, NY