The Biggest Loser, NBC's surprising little reality show that could, returns to the airwaves tonight, broadcasting its penultimate episode that culminates with next week's live finale crowning of the weight loss competition series' so-called "biggest loser" and $250,000 winner.

The 90-minute January 11 live unveiling of its winner will mark the end of The Biggest Loser first season original episodes, capping off a noteworthy run in which an unheralded series that wasn't even part of NBC's initial fall schedule launch emerged as one of the network's few fall season ratings successes.

Salvaging a Tuesday night time period previously occupied by an ill-advised third fall season edition of Last Comic Standing, The Biggest Loser premiered with few if any expectations and quickly established itself as a solid if unspectacular ratings performer for the network.

The performance caused a suddenly struggling NBC network to expand The Biggest Loser's originally planned eight hour-long episode run into an eleven-episode run that featured not only an obligatory holiday recap broadcast, but also featured numerous "super-sized" 90-minute broadcasts used to fill the time period vacated by NBC's highly promoted but critically panned Father Of The Pride animated series.

With its live finale unveiling and reunion broadcast, The Biggest Loser will reach a mark typically reserved for reality television titans such as Survivor and The Apprentice -- not a bad feat for a show that wasn't anywhere on the radar screen as recently as September.

The Biggest Loser's most recent December 14 original episode broadcast set new ratings highs for the series, drawing 11.0 million overall viewers and a 4.6/12 rating/share in Adults 18-49 demographic, a performance that not only outdelivered CBS's 9-10PM broadcast of the more critically-lauded The Amazing Race in Adults 18-49, but also ranked as the evening's best Adults 18-49 numbers among all television shows. The performance ranked as NBC's best non-sports non-Election Night results in the time period since November 3, 2003.

In the January 4 episode, its "payback time," as, after nine weeks of strenuous workouts at the hands of trainers Jillian Michaels and Bob Harper, the four remaining contestants turn the tables and show off what they learned as they "train" the trainers. After that, the contestants will undergo their final weigh-in at the ranch and trim the number of remaining contestants to three.

With only three contestants remaining, the remaining "losers" will then say their tearful goodbyes and undertake the ultimate test -- returning to their regular lives without the support of their trainers and independently surviving the more than two months that will have elapsed before the live finale.

The Biggest Loser's four remaining finalists are Ryan Benson, Gary Deckman , Kelly Minner, and Maurice Walker.

After The Biggest Loser's 90-minute live season finale airs on Tuesday, January 11, Loser viewers will have one more chance to check in with the show before The Biggest Loser 2 premieres later this year -- NBC will air one last "bonus episode" of the series on Tuesday, January 18 from 8-9PM ET/PT.