Previously on The Biggest Loser Australia Cal was shifted from the black team to the blue thanks to The Fridge and Caitlin’s decision to sacrifice him, since he’s been kind of an arsehole to the team.

People won prizes like letters from home and Katrina won a visit from loved ones thanks to a fun challenge/auction.

Tonight Katrina trains her husband and her sons in the gym. Then the weekly challenge is the return of the STACKS ON challenge from previous years. They’re using sandbags for the weight and a sturdy wooden yoke to support them this time, not the weightlifting gear they’ve used in the past.

Shannan’s first trainer to Camp and he checks in with his Mums first. They’ve all done their “homework” so he’s quite pleased. Katrina says it went well, in fact.

Katrina’s worried her family won’t see the difference in her when they visit. She hasn’t seen much change in herself so she’s worried they won’t notice anything either.

But first, training? Shannan asks where the rest of his team is and the girls don’t know. Where’s Big Kev and Cal and… Shannan gets up and goes to the door saying they need to traiiiin. He goes through the door then comes straight back through with Katrina’s husband and her sons. Awwww! Lots of big hugs, she wasn’t expecting it today.

Spanner says she looks amazing already. The sons are looking at her a lot and seem quite surprised. She must have been working hard.

Shannan thinks the boys should get the real Biggest Loser experience, but it’s not about him showing them it’s about Katrina showing them what she’s learned and training them. Hah!

As Katrina leads her boys off Shannan calls to her and gestures across his neck, telling her no mercy. Katrina replies, “Train, don’t complain!”

Commando Steve has his team at Crossfit Norwest. Get them a bit out of their comfort zone, Steve says. Though it’s all the same sort of training they usually do at Camp. Kettlebells, rowing machines and so on. They’ve got to get used to not having Cal around and still training hard.

Sharon’s feeling better since their chat and now she wants to show him what she’s got in her. She’s got her emotions under control now and she’s giving it everything.

Katrina’s got her sons on the treadmill first. Spanner’s going to row on the machine. She’s pushing him to go “under 200” whatever that means. Spanner reckons she wouldn’t be able to do it but she swears she can. After he’s done it in 4 seconds too long Katrina’s right up on him saying it’s not good enough. Spanner reckons she let the boys off (the boys are both fit and healthy it seems, surprisingly) so she should let him off. Bugger what Shannan would want them to do, he’s not there says Spanner.

So it’s time to show them what she can do. Katrina gets her son to put the resistance up to 5 or 6 instead of the 3 or 4 Spanner was doing.

Katrina starts the clock and goes nuts. Spanner’s a bit more impressed now and the boys are amazed, one says he couldn’t do that himself.

After the workout Katrina says Spanner did alright on the rower, she was just busting his chops.

But now it’s time to say goodbye, awwww! Many hugs and tears.

Spanner says it’s helped him seeing she’s doing fine, so it hasn’t just helped Katrina.

But now it’s time for the challenge. Cal’s excited to be on blue for his first challenge.

The back lawn is set up with all the stacks on gear and fiery lanterns around the place. STACKS ON!!!

The record for Stacks On was set back in Season 4. 140kg for Sharif and 90kg for Teresa. Nobody’s broken them in any of the seasons since. Maybe today’s the day, Shannan says.

Each team has to pick three people to be the “strength” and they’ll be the ones carrying the weight. It’ll be two women and one man per team. The rest of the team has to decide who’ll be loaded up with 10kg sandbags.

What’s the reward? Letters from home. Lame, they just had a chance at that and Katrina just had a visit!

Hayley asks if Cal might be the lucky charm for blue and Kerry says he might be lucky but he’s no charm!

The trainers discuss strategies with their teams. Steve says the key is to try and break people as soon as possible. Cal’s going to be in it so someone on black will have to match him.

Black team’s weightbearers will be Craig, Sharon and Caitlin. Craig reckons he can beat Cal and he’s eager to give it a shot.

Cal reckons he’s the brains and the strength on the team. They’re going for Cal, Katrina and Natalie.

Black gets to pick a target first as they won the last weigh in. They pick Cal, of course. Cal starts whistling jauntily. Kerry tells us it’s not just about beating Cal today it’s about beating Cal every day!

Both teams are going after the strongest first to try and load them up nice and early. Blue’s gone for Craig with their first two choices.

Shannan tells us Cal’s shoulders had better be as big as his mouth, as Cal continues to taunt black. But it’s part of Cal’s plan, he says, he’ll be the sacrificial lamb while the girls don’t get any weight.

Black’s first to break ranks on the strategy, putting 10kg on Natalie. Natalie’s surprised, she thought she’d be last to get some weight.

Another set of bags for Craig, then black goes back to Cal.

Craig gets another set of bags on and says he’ll be able to lift Cal up the stairs. He didn’t mean Cal, he meant Kev, but then he says both probably!

Black puts some more weight on Natalie while blue put Craig up to 60kg. When they load him up he asks if they even put more weight on yet? Everyone has a chuckle at that.

Cal twists a little bit as Steve loads another bag on and Steve asks why he’s moving away and Cal asks why he’s pushing him, no need to start cheating!

Blue finally put some weight on Caitlin, before going right back to Craig again. Black put some more on Natalie after another go at Cal. Weights are picking up quite a bit.

Natalie’s looking a bit annoyed that they’re putting weight on her, but she’s still holding up. Hayley asks blue if they’re going Craig again and Craig says she doesn’t need to put ideas in their head!

Craig’s on 80kg, Cal’s on 60kg, Natalie’s on 30kg and Caitlin’s on 10kg.

Craig’s up to 90kg and the sweat’s starting to pour off Craig. Black wants to prove they can do this without Cal.

Cal gets another load of bags on his shoulders and then he’s out, gets the weight off his shoulders and steps off the platform. Katrina thought he was joking at first but nope. So much for the hope they had with him. They should have picked Big Kev!

Craig’s up to 100kg now. He’s trying to hold out as long as he can to take some of the pressure off the girls.

Natalie’s now up to 50kg after Sharon gets her first 10kg.

Blue’s realised Craig can’t take much more and so they’re taking the chance to start alternating on the girls, which is a smart move if Craig actually can’t hold on for long.

Katrina’s finally getting some weight on her shoulders!

Then after some weight on Caitlin it’s back to Natalie… who gets a bit unbalanced as Steve and Shannan put the weights on and has to drop the weight off her back.

So now it’s down to just Katrina, who only has 10kg so far which is the lightest.

Craig was aiming for 110kg but blue aren’t giving him the chance. Craig’s finally out anyway, drops the weight off his back and gets off the podium. Cal calls out to him to try and lift his arms afterwards and Craig tries, realises he can’t and has a good laugh with Cal.

Caitlin’s worried she’s going to faint if she stands still too much longer. All three girls make it to 40kg at the same time.

Caitlin’s looking more and more wobbly and she finally has to get the trainers to help her take the weight off. She’s in tears afterwards but everyone’s very proud of her effort.

So it’s down to the two Mums. Sharon versus Katrina. Neither wants to give up. Katrina wants the letters for her teammates, Sharon wants them for herself.

Katrina says it starts feeling really heavy around 80kg but she’s trying to focus and block out the weight. Sharon’s remaining stoic, but is starting to wobble a bit at 80kg.

90kg on Katrina, another 10kg to Sharon and she’s on 90kg too. That’s both of them equalling the record. Crazy!

Katrina’s up to 100kg, the new record. Sharon equals it but she’s wobbling badly. Katrina still seems rock solid though.

As the 110kg mark is hit with Katrina she says she felt her knees buckle a bit and she locks them back up because Sharon looks like she’s not going to give up.

Shannan’s astounded by the weights the girls are holding, especially given it’s only week four.

And at 120kg Sharon can’t quite hold the weight anymore. Katrina wins for the blue team, their first win since gaining Big Kev at the hay bale and container challenge.

And as the winner Katrina has the option to give the letters to black team as well and there’s no hesitation, Katrina says yes right away. She says she would have traded her own letter for Sharon’s anyway at the very least.

But as it’s rewards week the blue team get an extra prize – they get to spend the rest of the week at the Golden Door health retreat in the Hunter Valley. Nice!

Cal’s pretty stoked to be on the blue team now!

Time to go back into the lounge and open up their letters. Sharon’s first to open hers and the first one she sees is done in children’s writing so it’s one of her girls. Awww!

Many tears and sobbing and being happy to hear from family.

Jane’s is from a niece, or at least someone who calls her Aunty.

Cal’s is from his wife, more tears.

Craig has one from his brother or sister? His nephew wondered why Uncle Craig would want to lose the pumpkin, meaning his belly. Hah!

Big Kev’s is from his Mum. Awwww! His Mum tells him he has lots of fans at the bowling club.

Shannon’s letter came with a picture of her and her daughter in Biggest Loser shirts, cute! Shannon’s feeling pretty homesick, pondering going back home.

Next time on The Biggest Loser… blue team’s trip turns sour for Natalie. She has a bust up with Shannan, I assume during training.

Caitlin’s got a “guilty, gooey pleasure”, which looks to be some kind of nougat or something?

Then on the scales Shannon says something to upset Shannan and Mr Voiceover Man suggests Shannan might walk. Or maybe Shannon might walk. Or maybe both and they’ll run into each other and bump noggins and their brains will swap and suddenly Shannon has to train the contestants while Shannan trains hard in his new body and the producers try to explain why both are talking a bit funny…