Three kids and 15 adults begin their weight-loss journeys in the Season 14 premiere. Trainer Jillian Michaels also returns to the show.

The players push themselves during exercise sessions at outdoor gyms set up by the trainers; the adults receive health assessments; the NFL's Antonio Gates encourages the contestants during a football-theme challenge; and the kids take a fitness test.

The players take a trivia test focusing on childhood obesity, and the losers must spend hours in a room with junk food, soda and video games; Dr. Dolgoff visits Sunny, Lindsay and Biingo's homes to help improve their families' eating habits; and the contestants race through a bubble-gum pit during a challenge.

The contestants are on their own this week when trainers Bob, Jillian and Dolvett leave town to surprise kid participants Biingo, Lindsay and Sunny and their families with a visit to their hometowns. Some players struggle without their trainer, but others rise to the occasion, and an unexpected leader emerges. In honor of this week’s "Pay it Forward" theme, contestants run a 5K and money is donated to a local Boys and Girls Club, with the winning team earning $15,000 to split among themselves. The trainers plan special surprises for each kid in their hometown before returning to the ranch in time for last chance workouts, when Jillian has a run-in with a player on another trainer’s team. Later, the weigh-in brings welcome news to one player who has been struggling, before another player is sent home.

This week kicks off with the players returning from a workout, only to find that the kitchen and refrigerators are empty. Tasked with trying to affordably stock the kitchen with a week’s worth of healthy food, the contestants race against time to make healthy purchases within their budget at a grocery. Later, one contestant struggles to keep trying her best despite weight loss setbacks, while Dr. H and one of the trainers help a contestant realize the importance of addressing the emotional issues that contribute to weight gain. Trainers Bob, Jillian and Dolvett skype with kid participants Biingo, Lindsay and Sunny, and then a swimming challenge puts the players to the test as they compete for one of the most coveted prizes of all. Finally, a tearful elimination sends another player home.

It’s the halfway point in the season, and the contestants find out that the weight of only one player on each team will count this week, but they won’t know who it will be until the weigh-in. With this week’s theme of “Leading by example,” trainers Bob, Jillian and Dolvett skype with kid participants Biingo, Sunny and Lindsay, and motivate each one to do just that. While Sunny creates a circuit training routine for her fellow classmates, Biingo tries to recruit more friends to his after-school sports club. Lindsay gives an anti-bullying speech to her peers, joined by special guest Cody Simpson, who also talks about his experience being teased before performing for the kids. The adult contestants compete in a crazy challenge requiring them to avoid three swinging pendulums while walking on a balance beam to retrieve calorie-coded plates matching five specific dishes.

It’s halfway through the competition, and the remaining eight players go to singles this week. The contestants face their first temptation in honor of Valentine’s Day, featuring favorite Valentine’s Day treats and the promise of the winner getting a weigh-in-advantage for themselves and a friend. Meanwhile, the trainers continue to motivate the kid participants to stay active and work toward their goals at home. Jillian arranges for Sunny to take a Bollywood dance class, Dolvett motivates Lindsay to attend a cheerleading practice, and Biingo anxiously waits for news from the doctor about whether he’ll be able to start practicing for the youth baseball league tryouts that Bob set up for him. Back at the ranch, one player displays an amazing act of kindness, and another has an emotional, heart to heart talk with a trainer about the circumstances leading to his weight gain.

The players work together to lose 70 pounds in order to win immunity for all; the kid participants are tested in a pop challenge; a sand-digging challenge offers a weigh-in advantage; the trainers and players participate in a team-building exercise; Subway's Jared Fogle offers words of wisdom; and Jillian and the kids endorse Seventeen magazine's "Body Peace Treaty.

Two players leave the ranch during a week devoted to facing fears. Others confront fears that include sharks, confined spaces and singing in public. Also, a challenge atop a seven-story building is planned for the contestants. Elsewhere, Sunny has a difficult conversation with her mom; Lindsay learns about the daily life of a diabetic; and Biingo tries to eat vegetables.

The contestants receive makeovers, with fashion guidance from Tim Gunn and new hairstyles from Ken Paves. They then return home to reveal their new looks to friends and family. Meanwhile, the players aim to lose a certain percentage of body weight in order to win immunity for everyone.

The winner of the $250,000 prize is crowned in the Season 14 finale, and the eliminated players return to weigh in for the $100,000 at-home prize.