Father and son team, from left, Chris and Mark Holmes prove a challenge.
Helping a group of obese people shed their excess kilos has always been physically demanding for the team from Channel Ten's weight-loss series The Biggest Loser.
But this year's twist on the format, which pairs overweight parents with their children, has proven emotionally taxing for the show's trainers, especially Shannan Ponton.
Calling from "an undisclosed location" as the show enters its final week of filming, Ponton is enthusiastic about this season of The Biggest Loser (subtitled The Next Generation) drawing towards its conclusion, but also candid about the hardships and pleasures the process has offered.
Gerald Nester, left, and his son Todd battle the bulge after Todd revealed his troubles with bullies.
Along with fellow trainers Michelle Bridges and "Commando", Ponton has this year taken on the challenge of breaking the cycle of generational obesity in Australia by bringing together combinations of mothers, fathers, sons and daughters in a bid to rid them of both excess weight and the psychological and emotional burdens that contribute to their physically unhealthy state.
It's the mental breakthroughs that tend to yield the greatest results on The Biggest Loser, Ponton has found during his seven-year stint on the show.
"Issues that have been suppressed for a really long time are generally the cause of a weight gain," he said.
Parenting advice... New dad Shannan Ponton looks to Biggest Loser father and son teams for inspiration.
"It can be anything from childhood bullying to sexual abuse to an all-round lack of self-esteem."
But with the introduction of a parent-child dynamic in The Next Generation, Ponton is seeing something new: a sense of antagonism.
"It's almost like retribution at times," he said. "The parents try to talk to the kids about their weight and the kids go 'Oh, so I'm fat, am I? Watch this, then!' and they self-sabotage themselves as payback against their parents. Because the parents are overweight themselves, the kids sometimes see it as hypocrisy."
The ads leading up to this year's The Biggest Loser's premiere have indicated the parents and kids taking part are presenting a caring and united front in their battle of the bulge. Ponton says that is actually the case in many situations, especially as the season progresses, but he adds it's not an easy road the contestants are travelling.
"It's a really twisted relationship that exists between a morbidly obese parent and a morbidly obese child," he said.
"From the parent's side, there's regret, remorse and, to a degree, resentment that they've raised an obese child. From the child, there's resentment and blame levelled at the parent.
"It twists the relationship and closes the channels of communication. The parents say, 'You should do something about your weight', the child tells them to shut up or binge-eats."
That build-up of anger leads to some fiery confrontations between the generations, something that often left Ponton and the Biggest Loser crew amazed.
"I'll tell you, my father would have knocked me into next week if I'd behaved the way these kids do," Ponton says with a laugh.
But confrontation can lead to catharsis and The Next Generation also offers parents and children the chance to begin living happier, healthier lives.
"For a lot of the parents, this is the first time in their lives they've had a platform where they can stand up and be the role models they've always wanted to be," Ponton says.
"It allows them to get rid of a lot of guilt. More than that, though, it allows them to stand up and be the kind of parent their kid can look up to."
A new parent himself, Ponton has been inspired by some of the acts of love and devotion he has seen between the generations taking part in this year's Biggest Loser.
"At the beginning of the season, we take a crack at everyone," he says. "Michelle, Commando and myself have different styles and it gives the contestants the chance to take the best from each trainer. It works incredibly well.
"But in my team now, I have this amazing father and son. I'm looking at this dad, who has become this incredible inspiration to me as a new father. I'm looking at his way of parenting, the messages he's sending and I thought 'I want to be like you, mate'.
"It's had an amazing effect on me, watching them, and my heart and soul is totally invested in this season. It's really got me, this one."
Ponton called the final stage of a 10-week Biggest Loser shoot "the joy of all joys as a trainer".
"It's fantastic, mate - you're down to the final few people, they're all fit, all motivated and all have their eyes on the prize," he says.
"They're up for any challenge I put in front of them, so that's wonderful.
"The mind-numbing, back-breaking part of the training is the first month or two, where they're broken physically, mentally and spiritually.
"This part of the journey, where we are now, is just a treat. I look forward to going to work every single day."
The Biggest Loser premieres on Network Ten on Sunday, March 17 at 6.45pm.