5 Most Dramatic 'Biggest Loser' Transformations

Jillian Michaels returns for the first time since Season 11, and 15 adult contestants will be joined by three teenagers hoping to change their lifestyles -- and possibly save their own lives, in some cases -- as the 14th season of "The Biggest Loser" kicks off Jan. 6 (NBC, 9 PM). In honor of the show's return, here are five of the most dramatic and inspirational transformations in the reality series' history. — Kimberly Potts, Yahoo! TV