Join Britney Spears's ex-husband Kevin Federline, rescued Beaconsfield miner Brant Webb, AFL legend Robert 'Dipper' DiPierdomenico and five other celebs and as they battle it out in the ultimate fat-fighting contest.

The contestants head to the first check-in and the three-part health measure of body fat percentage, waist measurement and fitness score is revealed to each contestant as their starting benchmark.

While K- Fed lies hooked to a machine in hospital, the other contestants take on a blindfold obstacle course. Lisa steers Darryn Lyons into obstacles instead of around them, and the resulting tantrum sees Darryn facing off with Matt.

K-Fed is back for the swimming challenge off Daydream Island. Lisa once again has Darryn seeing red, and Dr Tim reveals Lisa and Sarah will have to face their fears with scuba diving.

Lisa struggles at first to master scuba diving but finds the roles reversed as Darryn's overconfidence has him floundering and gasping for air.

The teams are marooned on Whitehaven beach and must build rafts to reach Dr Joe's rescue boat. Christine and Nathan hit the water first, but can they grab maximum points as an overworked, overwrought Matt becomes the Incredible Hulk

The teams are in Tassie and have to catch a fish at a salmon farm, but first they have to inflate two-person kayaks and race to fetch their rods.

The yellow, blue and green teams face a mighty, 140m abseil down a dam. Dr Tim is at hand as fear of heights freezes some of the contestants.

Four injured contestants force the formation of three super teams to take on a grueling orienteering course with five testing challenges along the way. The water-on-the-brain-teaser has Darryn Lyons wishing his business manager was there to help, and the feuding Matt and Lana must overcome their differences to have any chance of winning.

John and Lisa triumph in the weekly fitness tests. It's been neck and neck between Orange and Purple all week in Tasmania, who will come out on top when their health scores are revealed at the second competitive check-in?