Edited sentence: Personal trainers Michelle Bridges and Shannan Ponton are responsible for training the contestants and helping them to lose weight.Season 4 began filming at Fitzroy Island in Far North Queensland, before moving to North Head, Sydney.Seasons one to three of the show were filmed in Terrey Hills, one of the northern suburbs of Sydney.The Walk was filmed at Bobbin Head in Ku-ring-gai Chase National Park, Turramurra, New South Wales.The series involves contestants who are overweight to varying degrees participating in a contest to lose the most percentage of weight, with teams and contestants voting out each other.They have been the main trainers since Season 2 (in Season 1 the original American trainers Bob Harper and Jillian Michaels were used, and in Seasons 2 and 3 they appeared as guests).Unlike the American version, weight loss is measured in tenths of kilograms instead of pounds