Official NBC synopsis
The first reality series in which everybody "loses," "The Biggest Loser” challenges and encourages overweight participants to undergo physical makeovers, without any kind of surgery, in a safe and recommended manner through comprehensive diet and exercise as they compete for a grand prize of $250,000.

Season 5
5-1 "They Got Fat Together, Can They Get Thin Together?" (01.01.08)
5-2 "Contestants Face Barbecue Temptation and Giant Seesaw Challenge!" (01.08.08)
5-3 "Tensions Run High As This Week's Challenge Causes Rifts Among Players" (01.15.08)
5-4 "One Outcast Duo Squares Off Against All the Rest" (01.22.08)
5-5 "Surprise Escalator Challenge Changes the Game Forever" (01.29.08)
5-6 "Celebrity Chef Rocco DiSpirito Guest Stars" (02.05.08)
5-7 "Special Guest Appearance by Jillian's Mom" (02.12.08)
5-8 Contestants Reunited With Loved Ones (02.19.08)
5-9 "One Team Surprised With Trip to Vegas" (02.26.08)
5-10 "Contestants Tackle One of the Biggest Challenges in Show's History" (03.04.08)
5-11 "All Contestants Return to Ranch in Surprise Twist" (03.11.08)
5-12 "Contestants Made Over by Fashion Guru Tim Gunn" (03.18.08)
5-13 "Competition Heats Up With Only Six Contestants Left" (03.25.08)
5-14 "Last Five Contestants Get Surprise Trip to Australia" (04.01.08)

Season 5
Lynn Westphal (60, Elyria, OH)
Jenni Westphal (31, North Ridgeville, OH)
Curtis Bray (35, Los Angeles, CA)
Mallory Bray (36, Los Angeles, CA)
Neill Harmer (28, Oklahoma City, OK)
Amanda Harmer (29, Oklahoma City, OK)
Bette-Sue Birkland (53, Mesa, AZ)
Jenn Widder (22, River Edge, NJ)
Jackie Evans (49, Frankfort, IL)
Trent Patterson (39, Endicott, NY)
Paul Marks (43, Rockledge, FL)
Bernie Salazar (27, Chicago, IL)
Maggie King (23, Denville, NJ)
Brittany Aberle (22, San Jacinto, CA)
Dan Evans (21, Frankfort, IL)
Jay Kruger (31, New Bedford, MA)
Ali Vincent (32, Mesa, AZ)
Kelly Fields (38, Titusville, FL)
Mark Kruger (35, Dartmouth, MA)
Roger Shultz (40, Enterprise, AL)