The season premiere kicks off with the contestants arriving at the ranch in teams of two, including mother/daughter, father/son, sisters, best friends, grandparents, cousins, an engaged couple and former models. Included among them are the series' oldest players yet (63-year-old grandparents), youngest male contestant (18), heaviest female contestant (379 lbs.) and heaviest contestant ever in the history of the show (454 lbs.). Alison Sweeney hosts and trainers Bob Harper and Jillian Michaels return to train the 11 couples who begin the show with a combined weight of more than 3.5 tons.

This week, the contestants are faced with a temptation that will cause each of them to examine the real reason they've come to the ranch. Then it's off to an outdoor challenge, where they'll race by sea kayak and then on foot to the top of a mountain, hoping to win immunity as well as a coveted phone call home. Later, one contestant pushes trainer Bob Harper to the limit, causing him to freak out during last chance workouts before a surprising weigh-in leads to a heartbreaking elimination.

This week kicks off with a temptation that host Alison Sweeney tells the contestants will allow one player to reunite with their teammate at home and bring their trainer with them. But the reunion doesn't go exactly as planned when fireworks erupt between the two teammates after one player accuses the other of not doing all she can to stay on the ranch. Meanwhile, the contestants check in with Dr. Huizenga to see how far they've come and how many medications they no longer need from the first three weeks of weight loss. Then a wild jump rope-like challenge results in immunity at this week's weigh-in for the winner, followed by a surprising elimination that sends another contestant packing.

It's Super Bowl week on the Biggest Loser ranch, and that means food, football and fun with two special guest stars - celebrity chef Curtis Stone and NFL MVP Kurt Warner. First, Stone tests the contestants' calorie knowledge of traditional Super Bowl snacks, then teaches them how to make healthier versions. Later, one contestant has to leave the ranch for a very important arrival at home, while another surprises her teammates with a new change in attitude. Then it's time for the challenge, when Warner puts the contestants through an NFL-style drill that will give the winner an especially valuable prize this week. Then the partners who were sent home for 30 days while their teammates stayed on the ranch are welcomed back. But the reunion celebration is quickly followed by a tense weigh-in and elimination that will leave one team heading home.

Now that the contestants' partners are back at the ranch, those who've been working out at home will weigh in and see how they have fared away from the ranch. Then all the players compete in this week's "rope challenge," and later, an elimination leads to tension on one team when one player thinks her partner hasn't been pulling her weight.

This week, the contestants hike up a hill to find over 100 keys, but only two teams will find the keys that unlock the Biggest Loser gym. The rest of the teams have to learn to creatively work out all week without the use of the gym. Later, a rowing machine challenge pits team against team, and then a surprising turn of events leads to one contestant heading home.

This week brings a shake-up no one sees coming when all of the contestants are divided into just two teams, blue and black, leaving many players without their original trainer. Drama ensues, especially with one team who struggles to get used to their new trainer. And contestants are put to the test with one of the longest challenges ever, in which each team tries to put as many miles as they can on their bike in a 24-hour period.

In part two of this week's two-part episode, the contestants continue to adjust to their newly formed blue and black teams. They also meet Prevention Magazine editor Liz Vaccariello and take a pop quiz about health and aging. Then it's a grueling last chance workout leading up to weigh-in, after which another player is sent packing.

The players get a blast from the past when Season 5 winner Ali Vincent, and Season 6 winner Michelle Aguilar pay the ranch a visit. (TV-PG)

One player gets the only vote at elimination and two players from last season return to dish out advice.

It's one of the most eagerly-anticipated events every Biggest Loser season - the makeover episode! And fashion guru Tim Gunn returns to help the final seven contestants look their stylish best after all the players get complete salon makeovers from guest hair stylist Tabatha (Bravo's Tabatha's Salon Takeover) and celebrity stylist Brandon Martinez. Then it's time for amazing transformations and emotional reunions when the made-over contestants show off their incredible new looks to loved ones flown in to help them celebrate their big day. Also, the contestants soar to new heights in this week's challenge, and one player is sidelined with an injury that will have a dramatic impact on her workouts.

Bob and Jillian take the players on a field trip to teach them healthy grocery shopping on a budget, and one player hits a weight-loss milestone.

This week, the tables are turned when contestants get to train their trainers and are only too happy to put Bob and Jillian through the paces! Later, the remaining five players have to race up and down hills while carrying bags representing their total weight loss so far in a particularly grueling challenge. Then it's time to visit Dr. Huizenga for a progress report and to find out their new "real ages" now that they've lost so much weight. The players also try on their "goal outfits" and are amazed to see how far they've really come. Then after weighing in and eliminating one more contestant, the final four players head home, where they'll stay for 30 days before returning to weigh in at the ranch one last time.

The final four contestants go home for 30 days, reunite with friends and family and experience firsthand the challenge of continuing to make diet and exercise a priority back at home. Contestants also learn from host Alison Sweeney what their final challenge of the season will be - running a full marathon when they return to the ranch for their final weigh-in. Completing the full 26.2 mile course will be their toughest challenge yet, but cheering them on along the way are some past season "Biggest Losers"- grand prize winners Ali Vincent and Michelle Aguilar, plus "at home" winners Jim Germanakos, Heba Salama and Bernie Salazar. And as an added incentive, each player who finishes the marathon will get $10,000 to donate to the charity of their choice. Later, it's the very last "last chance workouts" with trainers Bob Harper and Jillian Michaels before a final weigh in determines who the two definite finalists will be - and which two contestants fall below the dreaded yellow line, leaving America to vote which one will be the third finalist to compete for the grand prize of $250,000.