The teams compete for exclusive use of the gym during a battering-ram challenge. Bob and Dolvett, meanwhile, try to get through to contestants they feel aren't putting in enough effort to shed pounds.

The contestants receive makeovers before traveling to Washington, D.C., to meet Michelle Obama and debut their new looks to friends and family. Fashion pro Jeannie Mai and celebrity hairstylist Ken Paves assist with the transformations.

The contestants go to Hawaii to test their ability to lose weight during vacation. During the trip, the players face off in a trivia contest and a challenge involving tikis and leis. Later, surfer Bethany Hamilton gives the gang surf lessons.

The players compete in a trampoline challenge to win the chance to exclude a contestant's weight from the weigh-in. Elsewhere, two eliminated players return for a chance to win a spot at the ranch, and personality clashes cause tension in the house.

This week, the age-old excuse "I'm stuck in my comfort zone" is addressed as contestants are pushed out of their comfort zones by switching trainers for the week. The red team works out with trainer Bob Harper, while the black team burns calories with trainer Dolvett Quince. And one trainer gets out of his own comfort zone by trying ballet with his female contestants! Also, the teams get down and dirty in a 70-foot wide mud pit, filled with various weight plates they have to find in a messy challenge that will give one team a big advantage. Then it's time for the weigh-in, followed by an emotional elimination sending one more player home.

A new batch of couples arrive at the ranch and are shocked to learn they'll be split up to compete against each other in the Season 13 premiere. The new round has a "No Excuses" theme, and the trainers address the reasons the contestants are overweight.

The teams bet on the percentage of weight they think they'll lose in order to gain an advantage at the weigh-in. Elsewhere, the contestants learn to shop for healthful foods; the teams compete in a puzzle-based challenge; and Dr. Huizenga performs sobering health assessments.

The contestants go home for 18 days and have a chance to earn immunity if they lose five percent of their body weight. While some struggle to stay on track, others benefit from the support of family and friends. Also: a home rowing challenge earns the winner $10,000.

The teams are dissolved, leaving the nine remaining players to compete on their own. Later, a tug-of-war contest finds the contestants competing for a shopping spree with Jessica Simpson; a trainer helps a player face her fear of heights; and a contestant turns the tables on a trainer.

Two players visit home with their trainers in tow, and their weights alone count at the weigh-in. Elsewhere, the teams compete in an obstacle course in order to receive letters from loved ones for Valentine's Day; the players at the ranch must fend for themselves, though one contestant turns to nutritionist Rachel Beller for help preparing a special meal.

A temptation-challenge winner reorganizes the teams in an unpopular move that creates tension and suspicion among the players. Elsewhere, the teams race to assemble a large puzzle in order to win a special prize.

Season 12 favorites Antone, Becky and Vinny return to judge a cooking contest and offer the players advice. Elsewhere, the contestants' exercise routines are spiced up with a Zumba class and mountain biking; and the players load food onto trucks during a pop challenge.

Michelle Obama discusses health and fitness with the six remaining players and meets with their families. She also joins the gang for a workout at the White House. Elsewhere, Bob counsels a player who turns to food for comfort; and Dolvett leads a last-chance workout in front of the Ulysses S. Grant Memorial.

A Chinese-buffet temptation offers the winner a two-pound advantage at the weigh-in and an opportunity to match up players for a gym challenge. Later, the teams compete in a water-transfer challenge for the chance to video chat with loved ones; a player makes a shocking decision.

One team must work out for a week without the guidance of their trainer, who secretly monitors his players to track their progress. The losing team is determined by a dunk-tank challenge, in which Bob and Dolvett are suspended over water and must rely on the contestants to keep them dry.

Previous winners John Rhode, Olivia Ward and Patrick House return to take on a difficult obstacle course along with the players. Also: The contestant who loses the highest percentage of weight for the week wins an SUV; the trainers and players watch videos documenting their progress.

The contestants from this season return for a special reunion and a chance to weigh in one last time - and show America how much weight they've all lost since beginning their weight-loss journeys. Those who have been eliminated will compete for the $100,000 "at home" prize. Then it's the moment viewers have been waiting for, when one of the three finalists will be named this season's "Biggest Loser" and win the coveted grand prize of $250,000!

The stakes are higher than ever when all the eliminated contestants return to the ranch to compete in a fateful, four-part challenge. The challenge winner will secure a coveted spot as a finalist, and the chance to compete for the $250,000 grand prize, along with the other two finalists revealed in last week’s episode. It’s a fight to the finish with each player fiercely determined to get back in the game in a competition that will put their speed, knowledge and endurance to the ultimate test. In the end, the third finalist of season 13 will be revealed.