The Biggest Loser: Couples is the fifth season of the NBC reality television series The Biggest Loser. The fifth season premiered on January 1, 2008 with ten overweight couples competing for a cash prize of $250,000. This season featured Alison Sweeney as the host, with trainers Bob Harper and Jillian Michaels; all three returning from season four.

Although the contestants came in as teams of two, the grand prize was eventually awarded to an individual. In the end Ali Vincent won, making her the first female winner in the history of the United States Biggest Loser series.