The Biggest Loser is an American reality game show that debuted on NBC October 19, 2004. The show features obese people competing to win a cash prize by losing the highest percentage of weight relative to their initial weight. Each season of The Biggest Loser starts with a weigh-in to determine the contestants' starting weights, which serve as the baseline for determining the overall winner. The contestants are grouped into teams of two, each wearing separate colored t-shirts. Depending on the season a team may work with a specific trainer or all trainers may work with all contestants. The trainers are responsible (in conjunction with medical personnel retained by the show) for designing comprehensive workout and nutrition plans and teaching them to the contestants. However, the contestants are individually responsible for implementing the principles taught. During an episode, various challenges and temptations (see below) are featured.