When the subject of The Biggest Loser came up recently, a colleague said, "You know, that's the show with Charlotte Rae."

Actually, the host of The Biggest Loser is comedian Caroline Rhea. Charlotte Rae is the woman who played Mrs. Garrett on The Facts Of Life.

Then again, the last time we saw pictures of Blair, Natalie, Tootie and Jo, at least a couple of them would have been prime candidates to go on a reality show about weight loss.

But hey, who couldn't drop a few pounds?

And it's that universal truth that gives a program like The Biggest Loser its emotional hook, particularly in the junk-food culture of North America. It's worth noting, though, that the show has been exported to Great Britain and Australia, too.

A David Letterman top-10 list that we saw recently revealed the top 10 questions a department-store manager asks when hiring a Santa Claus. One of the queries was, "Is your lap strong enough to support today's obese children?"

That's funny and sad all at the same time.

Anyway, the live, two-hour season-finale of The Biggest Loser is on tap tonight (CH, NBC, 8 p.m.). The final four contestants will weigh in one last time for the chance to win $250,000 US (kinda chintzy by reality-show standards), and then all 50 contestants will return to reveal their (hopefully) startlingly slim bodies.

This is the third season for The Biggest Loser, which structurally has a lot of similarities to Survivor. Instead of torches being extinguished, though, refrigerators are shut off. Cute.

The Biggest Loser has grown from a dozen contestants in Season No. 1, to 14 contestants in Season No. 2, to 50 contestants -- representing each of the 50 states -- in Season No. 3. The final four contestants this year are from New York (Erik), Alaska (Kai), Florida (Wylie) and Utah (Heather).

Dare to dream, Wisconsin.

Kai and Heather both are vying to become the first female winner of The Biggest Loser, which bases its results on percentage weight loss.

Case in point: At the conclusion of last week's episode, it was revealed that Erik -- who began the competition at 407 pounds and has plummeted to 283 -- has set a record for the show by shedding 124 pounds. That accomplishment notwithstanding, Erik is not automatically the winner.

The four competitors vacated the training facility at the end of last week's episode and the live finale is occurring several months after that departure. The final weigh-in will reveal whether Erik, Kai, Wylie and Heather have been able to continue losing weight while back in the familiar surroundings of their own homes and lifestyles, or if they've fallen off the Whopper wagon like so many of us waist-watchers have done before.

Like The Bachelor, it's highly debatable whether this finale really needs to be two hours long. But The Biggest Loser arguably leads the reality-show league in tears-per-minute, and surely every emotional chord that can be struck, will be struck.

And who knows? Maybe Lisa Whelchel, Kim Fields, Mindy Cohn and Nancy McKeon will drop by.

As Mrs. Garrett would warble, "Girls, girls!!!"