The twelve contestants enter the house and absolutely love it. However, soon they realize there's no furniture. Two big trucks arrive and the contestants have to assemble the house! Later, called into a separate room, filled with delicious food, the contestants are given one last 'meal' before commencing, after which contestants suffer their first ever weigh in, with heartbreaking results. Bob and Jillian arrive to pick their teams.

After arriving to find Camp Biggest Loser empty, Hayley revealed the reason to the trainers: not only would they each have to train a family, but spend a week living (and eating) with them. Whisked away by helicopter to their respective new homesteads, Shannan, Michelle, The Commando and Tiffiny saw their momentous task first-hand, piling their plates in a truly eye-opening, waistband-expanding new experience. The families were awarded their team colours – Westrens (Blue), Moons (Black), Duncans (White), Challenors (Red) – before learning they would have their first weigh-in publicly, for all their loved ones to see.

The public weigh-ins took place, Damien from the Challenors making Biggest Loser Australia history as the show’s heaviest contestant at a staggering 234.4kg. The teams and trainers were taken by limo to their new home – Camp Biggest Loser – where Hayley revealed the $300,000 prize on offer, and announced training would begin immediately. Tears, breakdowns and vomiting ensued as the first training session made each contestant face the reality of the journey they were about to take.

The contestants were amazed to discover that in another Loser first, it would be the trainers weighing in. The results were a surprise to all, and not about to go unpunished. The contestants were woken at an unsociable 5am for a gruelling training session, after which they were given their bio ages by resident Doctor Swan. Each family member then recorded a video message to their future selves. That night the contestants were presented with their first Contest, endurance: a three-round, 10km race on the treadmills. Jodie, Leigh, Joe and Jarrod were chosen as the contesting champions, with The Blacks and Whites left at the final round.

As the contest continued, Jarrod from The Duncans emerged victorious and was awarded the power to remove another family of their trainer until after next weigh-in, choosing to penalise The Moons and gleefully ordering The Commando to take a hike. The contestants trained, Sharlene had a breakdown which later turned into a breakthrough, and the families began their first Challenge – pulling an 88 tonne train 400 metres. The prize? A 4kg advantage at next weigh-in. The battle was tight, but The Duncans were edging ahead at the close.

The Challenge pushed each contestant to the limit, and the Westrens’ Craig further, as he collapsed from the effort. The Duncans once again brought victory home, winning an all-important 4kg advantage at weigh-in. Big numbers fell at the weigh-in, with Jarrod crowned the week’s Biggest Loser, and The Duncans Biggest Losing Family. The Challenors and The Moons fell beneath the yellow line, and each nominated a member to face eviction. Rebecca and Greg went off to meet their fates, and Greg became the first contestant eliminated.

The Red Team’s reaction to Greg’s elimination shocked many. The teams entered the lounge to find a note instructing them to ‘Go outside, a trail awaits.’ Little did they know the trail would take them to Temptation, picnic-style. Hayley explained that should anyone decide to take Temptation, they would have to race for a basket and eat what’s inside, while one basket contained $25,000. The catch being that whoever got the cash basket would have to leave the game if they wanted to keep it. Leigh was faced a life-changing decision, and Meg was lumbered with a 2000-calorie chicken meal to burn off. Michelle learnt news of Greg’s elimination and voiced her disgust, and the trainers turned up the eat on their families in post-Temptation training.

The contestants learnt of the family weigh-in, and Leigh decided not to gamble with his life, rejecting the money in favour of remaining in the game. A decision that delighted his trainer Shannan, who led his team in a demanding circuit training session. Michelle continued to voice her immense disappointment in her family’s continued refusal to follow her instructions, and the team finally agreed to work harder so Greg’s elimination wasn’t for nothing. The Commando fought to deal with rifts appearing in the Moon family, and Tiff awarded the Duncans their yellow belts. The Contest was one of strength, with three rounds of curling, and Damien and Jarrod were left battling it out for the win.

Realising the threat posed by the Duncans, they were the ones penalised. Despite Tiffiny doing her best to talk her team through how to make good choices from the menu, all the hidden ingredients made calorie counting difficult. The next Challenge began at ANZ Stadium; families each had to chose one member to sit out. Injured, the Challenors didn't compete, and were instead taken by Michelle to make amends with Greg. The Blues and Whites were leading the Challenge at the episode's end.

After clearing the air with Greg, the Challenors decided to devote the week to him. The Duncans were put through their paces by Tiff during Last Chance Training, while the Commando ran the Moons ragged on the treadmill. At weigh-in, the Blues and Whites fell beneath the yellow line, and despite Craig imploring the other contestants to vote him out, Sarah-Jayne was eliminated, causing friction between the teams.

Sharlene secured the prize for the Blues, much to Shannan’s dismay. All the trainers save Michelle were forced to chastise their trainees for taking Temptation. A particularly aggrieved Commando took the Blacks to a warehouse and put them through a torturous training session, at which Sarah could only watch as she was injured. As the episode came to a close the contestants entered the weigh-in room ready for this week's family weigh-in.

The Westrens won at the scales and got to decide the champions for the next Contest. Enraged as the Black Team’s apparent lack of motivation, The Commando put them through another intense workout, this time on the parade ground in the pouring rain. The theme for the next Contest was knowledge, with the champions each picking an assistant. Little did they know that for every wrong answer the helper would be loaded with a 5kg weight.

The Westrens won and selected the Challenors to ‘babysit’ a 5kg medicine ball for the week, having to keep it off the ground 24/7 until weigh-in. The penalty for failure was a second ball. Michelle took Joe to task for his reaction to the Reds being chosen. The Commado put the Moons through another taste of training torture, and the sand bag Challenge was revealed - the first family to load a tonne onto their scales would win a 1kg advantage at weigh-in, and letters from home.

The Whites narrowly won the Challenge title from the Blues, and won the 1kg weight advantage and letters from home. After a gruelling training session the remaining families all received their letters too. With only one spot above the yellow line, the weigh-in was tense, but the Duncan family emerged victorious. In a shock decision the Challenors decided to put Damien up for elimination, and believing the move to be a calculated attempt to win the sympathy vote, the other contestants voted unanimously to send him home.

The reaction to Damien’s Elimination was fierce, and the accusations poured down on Joe, who threatened to leave Camp Biggest Loser. Michelle was shocked by the decision, and that the others would vote the heaviest contestant out. The families were led into the weigh-in room and told to vote for the family they wanted out of the competition, which turned out to be the Challenors. The twist was revealed: the Reds would contest the rest of the week against the Team of Three Families. Training was brutal, and in a special event, more footage from the trainers' family stay was shown.

At the family weigh-in the Team of Three Families weighed in as one against The Challenors, and recorded a massive weight loss. The Champions for the ‘Super Contest’ were decided: Joe, Leigh, Jarrod and Kellie. Joe won the first round, before submitting to Jarrod in the second. With the power to bring a family member back into the game on the line, it was a hard fought battle between Joe and Kellie on the bikes at the close.

Joe emerged as the winner in the Super Contest, choosing Damien to come back into the game, who was welcomed with open arms. The trainers put the contestants through a punishing training session, after which Jodie opened up to Shannan about her battle with cancer. The Challenge began, though Damien wasn’t allowed to compete, with the winning team taking a 1kg per person advantage into the next weigh in. The Challenge was to load and pull sleds of water bottles, with the Reds surprisingly taking an early lead.

The challenge is completed, who will gain advantage at the weigh-in? At the weigh-in, it's 3 families against 1,who will be eliminated?

The teams reacted angrily to Jarrod’s Elimination, particularly that Joe wasn't respecting Nathaniel's opinion. Contestants entered the Temptation room to see big pictures of their loved ones hanging up, and were told that a chance to return home and see them was on the line. The families were blindfolded, and had to decide whether to dive into the bowls of chocolate buttons in front of them. Kellie won after eating a massive number, but suffered the Commando’s wrath as a result. As the family weigh-ins began, news of Jarrod’s weight gain on the outside shocked all.

The family weigh-ins continued, with the contestants shocked at Jarrod and Greg’s weight gains. The Westerns won the weigh-in and chose Rebecca, Nathaniel and Emma to compete against Lara in the Contest. The Contest was held at North Sydney Olympic Pool, and carried out over three rounds: Knowledge, Strength and Endurance. In the first round the trainers sat in row boats, and for each question their Champion answered incorrectly had to add four buckets of water to their boat. Tiffiny sank first, eliminating Emma. Rebecca was eliminated next as the contestants had to carry weights from one side of the pool to the other, leaving Lara and Nathaniel to compete in the final round.

As the pool contest continued it was between Lara and Nathaniel in the final round, Endurance. Lara won and with power over the game penalised the Moons with a 1kg disadvantage at weigh-in. After learning that his family hadn’t bothered doing an early morning training after receiving their penalty, the Commando let the Blacks have it, with Rebecca storming out of training. The Challenge was revealed to be a mud pit tug of war, with the four families hooked to each other and racing for flags in the four corners of the pit. It was a tight battle between Meg, Sarah, Damien and Leigh in the final round.

After a final push Meg captured the final flag and won the Challenge. Last Chance Training exposed further rifts in the Red Team, as Nathaniel voiced his dislike of Joe and his dismay at being marginalised by his uncles. Michelle tried to clear the air, and resolutions were made to put differences behind them. Good numbers were lost by most at the weigh-in, with Emma taking the week’s Biggest Loser for the second time this series, but the Westrens and Moons were left under the yellow line. Craig and Jodie went up for Elimination, and the former was the one packing his bags at the close.

After being told that fresh blood was arriving at Camp, the contestants were shocked to meet the team of Loser Legends – past players Adro, Sam, Bob and Lisa. The families learned that each team would be joined by a legend for the week, who would eat, train and compete in both Contests and Challenge with them. After getting to know their new additions in training, the families entered the weigh-in room, ready for the family weigh-ins.

Craig was the only outside contestant that gained weight at the family weigh-in, and the Westrens once again took Biggest Losing Family. Rather than choosing the Champions for the Contest however, they discovered that the Loser Legends would be battling it out. Sam took the first round on the rowing machines, while Lisa was the second Legend eliminated after the knowledge round. Sam and Adro then prepared to contest the final.

Training was intense for all the contestants, particularly Leigh, who was tested to the upmost by Shannan. The families were taken to the Challenge site, and told they had to carry buckets of water to the top of the sand dunes, tipping them into their barrel at the top to bring their key to the surface and release it. Sam and the Reds were the first to get their key, and release their flag for the win, giving the Challenors a 1kg weight advantage going into the weigh-in.