S12, E7: The competition shakes up this week when contestants change teams and trainers in a high-stakes, calorie-counting challenge that will determine who each player's trainer will be for the rest of the season. After the teams are re-aligned, dramatic confrontations follow between some players and trainers as they all try to adjust to their new reality. Later, the new teams face their first challenge together -- racing down a water slide on a hill to unscramble block letters that reveal the winning team's prize. Trainers Bob Harper, Anna Kournikova and Dolvett Quince each take their teams off the ranch to spice up their last chance workouts, and later, an especially emotional elimination follows a weigh-in revealing noteworthy results from the trainer/team switch. Alison Sweeney hosts the series.