"The Biggest Loser: Couples" continues tonight and the competition heats up when the blue and the yellow teams, who were sent home the first week, return to weigh-in. Whichever team has lost the most weight will get to return to the ranch.

Also on tonight's episode, in honor of Super Bowl week, the contestants face a football-tackling challenge that will test their stamina and give the winning team a coveted prize -- and a big disadvantage for the losing team.

Then Jo Bro Nick Jonas makes a special appearance in this week's Pound-For-Pound Challenge segment, volunteering his time at the North Texas Food Bank.

But first, ET talks to host Alison Sweeney to get her take on the hit weight-loss series.

ET: Do you think it's possible to keep getting bigger and bigger contestants? This season Michael weighed more than 500 pounds.

Alison Sweeney: He was 526 when he started. What we are finding is we are able to deal with people who are bigger and help them, which is what we are all about. It is a game and a TV show and all that, but what we are really trying to do is save someone's life and make a difference. We, obviously, want to be safe, but we are able to help them, we are able to give them the tools they need. I think John, James and Michael needed us more than the people who weigh 250 or 300 pounds. It is a life or death situation in some cases. So, if we can do it, keep them safe and help them get healthy, I absolutely agree with it.

ET: What was hard for me this season was on the first episode; the yellow and blue teams were sent home. I was, "I don't want to watch this because these people really need help." But then we found out that the team that lost the most weight at home in 30 days would get to come back to the ranch and that helped.

Alison Sweeney: Really, what I think the show proves is it is about setting goals, whether or not it is on campus, which is obviously an advantage. But no matter what it is, when you know that you are working toward a goal that is as reasonable as 30 days from now, you just do the best you can. I think that is the solution and that is what America can take away from it because most of America doesn't get to come to campus. If you can set the example of: Set that goal for yourself. Why don't you work for the next 30 days and see what your percentage of weight loss is, and watch the show and see if you would have made it back to the ranch? You can really inspire everybody at home, too.

ET: Pink has been a lucky color for several of the contestants. Both Ali and Helen were pink and they won; and Rebecca won the at-home prize last season. A lot of the time, the pink team starts at a lower weight, do you think America wants to see the 500-pound people get down to 300 pounds, or the 250-pound people get down to 125 pounds and look really good?

Alison Sweeney: It is hard when they don't win; they have so far to go. Shay had so much weight to lose. [Her starting weight was 476; her weight at the finale was 304.] She did really well to compete in the percentage of weight loss, but at the same time, Danny and Rudy did the same thing. They had a long journey. The show has 22 contestants. There is something for everyone.

ET: Speaking of Shay, how cool was it for Subway to come forward and make that offer to her? [Subway offered Shay unlimited sandwiches and $1,000 for every pound she loses between the finale and next season's "The Biggest Loser" finale in May 2010.]

Alison Sweeney: Either way, we wanted to be part of Shay's story. We wanted to continue it, but Subway making that generous offer was yet again reaffirming how business, television and entertainment can succeed by doing the right thing, by doing something good for people and everybody wins.

ET: What is interesting is several other chains are also jumping on that bandwagon.

Alison Sweeney: Everyone is trying to do a health kick. I have to be honest, I am not a big fan. I want to be very careful that people understand those are not diets. Those are healthier options. Kudos to you. Thank you for offering us something healthier, but if you think you can eat that everyday … home cooking is still the healthiest.

ET: Are there any really good stories coming up this season?

Alison Sweeney: There are a lot of amazing, wonderful, sweet people. Bob and Jillian have both said they think this may be overall the most sincere group we have had. There are really some heartfelt moments.

ET: Is there anyone like Tara, who we are really going to be rooting for?

Alison Sweeney: There are standout moments with each person, but there is not that one character who is really shining separate from the rest in a competitive way. They are a really hardworking group of people who have found a way to stick together.

"The Biggest Loser" airs at a special time tonight: 9 p.m. on NBC.

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