NBC has announced that The Biggest Loser's fourth season will premiere on Tuesday, September 11 at 8PM ET, marking the second time in the last three years that the network has previously announced plans to debut the reality weight-loss competition series during late summer but later decided to delay the show's launch until fall.

Back in April, NBC had announced that The Biggest Loser's fourth edition would premiere in late summer.  A couple weeks later, the network had announced that the premiere would air on Tuesday, August 21 at 8PM ET/PT.

Had the network followed through with its scheduling plan, The Biggest Loser's fourth season would have become the first The Biggest Loser installment to debut in late summer.

Two years ago, NBC announced that The Biggest Loser's second installment would get a jump on the network's fall schedule launch and premiere in August 2005. However a month later, the network decided to move the show's debut to mid-September.  Last year, The Biggest Loser's third season stuck to its originally announced premiere date and debuted with the rest of the network's new slate in September.

In addition to Alison Sweeney, the show's previously announced new host, The Biggest Loser's fourth season will feature several other changes, including a new "back to basics" concept that will take the show away from The Biggest Loser ranch and 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, for what NBC is calling a "a surprising new twist."

"The series will kick off with a bang when Jillian makes a surprise return to take on fellow trainers Bob and Kim to help change the lives of what is sure to be our most memorable group of Loser hopefuls yet," said new NBC Entertainment co-chairman Ben Silverman, who also serves as one of The Biggest Loser's executive producers.

Although NBC apparently intended to keep the details of the "surprising new twist" that results from Michaels' return under wraps for now, someone apparently forgot to share that plan with Michaels.

"Jillian returns to The Biggest Loser!  Jillian... [is] coming back as a surprise trainer to whip a secret third group of contestants into the best shape of their lives," a message on Michaels' website states.

"Ok, you guessed it (or at least most of you did) ... yes, I am returning to The Biggest Loser! That's right, this year there will be 3 teams -- Bob's, Kim's, and mine -- taking part in the competition," Michaels recently wrote in a letter to fans.  "I've been alluding to this for awhile now, but the master plan was in the works at NBC for over a year.  This has been the most difficult secret I have ever kept, and it was for an incredibly long time! I am SO stoked to finally share the news with all of you."

According to NBC, The Biggest Loser's fourth season will feature 18 contestants and include a 62-year-old -- the series' oldest ever cast member -- and a set of twins, a series first.  Although The Biggest Loser's fourth season contestants will be working out at a new location that doesn't have any of the ranch's luxuries, the show's format will still largely remain the same --  the contestants will still compete in challenges and weigh-ins and try to survive enough eliminations to win the show's $250,000 grand prize.

The show's second episode will air on Tuesday, September 18 at 8PM ET/PT and, like the premiere, will also be two-hours long.  The Biggest Loser will settle into its regular one-hour Tuesdays at 8PM ET/PT time period beginning September 25.

The week before The Biggest Loser's fourth season premiere, NBC will air a one-hour "Where Are They Now?" special that will give viewers an opportunity to see the progress -- or lack thereof -- that some of the show's contestants from the previous three editions have made. 
Reality TV World is now available on the all-new Google News app and website. Click here to visit our Google News page, and then click FOLLOW to add us as a news source!

"This is an innovative way to re-introduce an audience favorite and answer the question everyone asks - 'Did they keep the weight off?'" said Silverman.

The Biggest Loser: Where Are They Now? will air Tuesday, September 4 at 8PM ET.