The fourth season of the Australian version of the original NBC American reality television series The Biggest Loser, known as The Biggest Loser Australia: Couples, premiered on 1 February 2009 on Network Ten. Series Host Ajay Rochester reprised her role for the fourth season, along with trainers Shannan Ponton, Michelle Bridges and Steve Willis ("The Commando"). The show also introduced a new trainer Emma Hutton ("Emazon"). Applications opened mid-2008 for potential contestants. On 27 April, Bob Herdsman was crowned the oldest contestant in Australian History to ever win with a record weight loss of 87.6 kg, or 52.21% of his starting weight, and won $200,000 in prize money.