Ana Alvarado

This week kicks off with host Alison Sweeney issuing a challenge to the ranch-based contestants: if they have a higher percentage of weight loss than the "unknowns" -- the contestants working out with the two new mystery trainers -- they'll all have immunity this week. The "unknowns" fuel the competitive spirit by delivering messages and surprises to the contestants at the ranch reminding them just how tough their competition really is. Then Dr. Huizenga gives sobering news to contestants about their health risks and their real ages vs. their chronological ages, but this time, loved ones from home are involved to really help drive the message home. Later, the ranch contestants' ability to work together as a team is tested when they try to beat the time of the unknowns in a wild bridge-building challenge using rafts. Then a tense weigh-in reveals whether the ranch contestants are safe from elimination, or whether they'll be sending another player home.

Two new trainers and a compelling new twist deliver a game-changing season like nothing viewers have seen before when season 11 premieres with twenty-two contestants -- eleven family and friend teams of two. After the first challenge, contestants are given the unprecedented opportunity to choose whether to work out with trainers Bob Harper and Jillian Michaels at the ranch - or work out at a secret location with two unknown trainers and get four weeks of immunity. What ensues is a riveting ride of intense emotions, surprising turns and "can't miss" moments as the two groups fight their weight loss battles separately with two sets of trainers equally committed to giving these players a new lease on a healthier life. The contestants include an Olympic gold medalist, identical twin policemen, a pastor who wants to spare his overweight son from the challenges he faced because of obesity, and a woman who has lost pregnancies because of her weight and wants more than anything to be a mother. Alison Sweeney hosts the series.

It's Valentine's Day on the ranch, and host Alison Sweeney ushers the contestants into a room full of chocolate candies for a holiday-themed temptation. Whoever eats the most chocolate will have the option to trade two players on their team for two players on the other - or to keep the teams the same, and the winner will be a secret. But as teams are divided into red vs. black, the winner's choice causes upset in the house. Later, a five-part relay race challenge tests the players' endurance, speed, agility, strength and knowledge. Trainer Jillian Michaels takes one contestant horseback riding, and one team gets to enjoy heartwarming videos from home before a weigh-in results in a Biggest Loser record being broken and another player heading home.

Host Alison Sweeney tells the remaining 12 contestants that they will all be on one team this week -- the blue team -- and they will all have immunity if they beat their weight loss from the previous week. But first, there's a pop challenge in which they have to prepare delicious, healthy, low-calorie meals in under 30 minutes. Chefs Curtis Stone and Lorena Garcia will decide who prepares the best dish, with the winner getting a coveted prize. Later the blue team meets at a rock quarry where they'll have to uncover a buried rope attached to signs with trivia questions. If they answer the questions incorrectly, they will be led in the wrong direction, something all the players want to avoid since the winners get a huge advantage at this week's weigh-in. Later, Dr. Huizenga drops by with impressive medical updates, including the news that one contestant has already reached their goal weight. Then it's time for the weigh-in, when players found out if they all get to stay at the ranch another week -- or if they'll be sending one contestant home. Trainers Bob Harper, Jillian Michaels, Cara Castronuova and Brett Hoebel also star.

The contestants are faced with the "ultimate temptation" this week when each team enters a room filled with each player's favorite foods. Whoever eats the most calories gets to choose which team will go train with the "unknowns" and the new trainers. Later, the stakes are high with a calorie-counting challenge that will give the winners what they want most -- letters from loved ones back home. The trainers confront a contestant they think threw the last weigh-in, and later, trainer Jillian Michaels puts trainer Bob Harper through an intense yoga workout to show the players what they'll ultimately be able to do once they lose weight. Then one player takes matters into their own hands to try and send a contestant home. Alison Sweeney hosts the series.