S11, E2: 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.