Was there a problem with reality TV show The Biggest Loser?

When it first hit screens in 2004, The Biggest Loser was a ratings winner. Audiences couldn't get enough of watching unhappy and overweight people compete to change their lives and have a chance at scoring a $US250,000 prize.

We watched them working out to the point of vomiting, being berated by fitness instructors, pulling two-ton cars, tackling temptation challenges, and gorging on desserts. The show, which ran for 18 seasons, tread the fine line between mockery and entertainment.

Now, a new Netflix three-part documentary series, FIt For TV: The Reality of the Biggest Loser, takes stock of the show that saw its last season air in 2016.

Bob Harper, the former trainer-turned host who features in the series, told RNZ's Saturday Morning that he's still proud of what he helped contestants achieve on the show.

“It was a long time ago. Those moments where I was screaming, yelling, jumping up and down, seeing those temptations that were just so cringey, like all that, but I do look at the bigger picture and the people that really were inspired, not only the contestants, but the millions of people that were watching from home too.”

The documentary series drills down on the drama producers created, often at the expense of contestants who were vulnerable in offering up their obesity struggles for entertainment. While the average contestant lost 45 kilograms on the show, awarding the person who lost the most didn’t always lead to healthy strategies from contestants.

Some of the criticisms raised in the series include accusations that Harper and his co-trainer and co-host Jillian Michaels, routinely ignored advice from the on-set doctor that contestants were eating dangerously low amounts of calories. Michaels does not appear in the documentary series.

However, Harper says the concept of the show was groundbreaking when it first went on TV screens more than 20 years ago.

“We were bringing in weight loss into people's homes and producers wanted it to be as the show got more and more successful... the producers wanted it to be bigger and more exciting and you know, all this because at the end of the day, they were making a television show that ran for 18 seasons.”

Before The Biggest Loser, Harper had worked with mostly wealthy clients who were more interested in eating well and working out for aesthetics. The contestants he trained on the show were often in a lower income bracket with much more humble goals.

“...that was really eye-opening for me because I went from working with people that were trying to be like, you know, a size two and have a, have a six pack, to people that were just wanting to be around, to walk their kids down the aisle, grow old with their partners...”

The documentary series shows a divide between contestants' experiences. One left the show so changed and inspired that they named their child Harper after their trainer. Other contestants interviewed in the series say it was the worst experience of their lives.

The series highlights one scene from The Biggest Loser where Harper yells at a contestant running on a treadmill. She later described the experience as traumatic.

“...I look at it and just think, oh my god, I remember those days just being so long and so gruelling and not to make any excuse because I'm not making an excuse, but, yeah, that wasn't one of my finer moments.

“But I look at the whole of it all, and I knew that, like, when it was time to do the on-camera workouts, our job was to make it as crazy and as exciting as possible.

“Those were the producer notes that I would always get.”

Harper says that for the most part, the contestants understood the nature of reality TV with its heightened drama for the sake of entertainment.

“It had to be crazy, but, you know, we were all adults and we kind of all knew what we were signed up for."

One contestant interviewed in the series is Danny Cahill, who lost an astonishing 108 kilograms to win season 8. He says there was a lack of support from producers after each season to help contestants maintain their weight loss. Harper says he believes there was an element of personal responsibility that contestants needed to take on once each season ended.

“Because that weight is going to be just tapping you on the shoulder every day, going like this. All right. You know, are you going to keep continuing to do what you do? And so you've got to find your own support group at home.”

And a follow-up show on maintaining weight loss? Boring.

“...there was no producer that was going to do that show,” he says.