Fitness expert Bob Harper spent a dozen years training contestants to lose a lot of weight in a short amount of time on the original, NBC incarnation of “The Biggest Loser,” a show he calls “the O.G. fitness reality series.” But in 2017 he suffered a major heart attack that had him rethinking his approach to exercise. So when he received a call from the producers of the new, USA version of “The Biggest Loser,” he had questions about what their approach would be, given the way fitness is discussed has evolved in the few years since the show went off the air. Ultimately, it was the idea that they would bring his health issues directly into the show that made him want to step back onto the campus: Confronting how important it is to be healthy, not just thin, was relatable to him and, he hopes, everyone who came on the show and would be watching at home.

In the new “Biggest Loser,” Harper is a host, not a trainer. And he also leads a support group where the contestants — on both teams — come together to talk openly and candidly about what they are going through day-to-day on the show, as well as what they have experienced in their past that led them to the point of needing to be on a show like this in the first place. Immediately, Harper tells them about his heart attack because he felt he had to “practice what I preach,” he tells Variety. But just as the contestants opening up with each other helps them heal, he, too, got something new out of the experience.

In the original version of the show, he says, “I was very attached to my team and living and dying for them.” But here, Steve Cook and Erica Lugo are the trainers so Harper “didn’t have the pressure of that anymore, and it was liberating because I got to work with everyone, and I really enjoyed that. When you were in the support group, nobody saw color: it wasn’t about blue versus red, it was about, ‘Why am I here in the first place?’ There were lessons to be learned, and I’m dealing with life and death here, so I’m going to do whatever it takes to help you in any way, as positively as I can [and] also as realistically as I can.”

The support group plays very prominently into each episode, which means the traditional “Biggest Loser” format has been tweaked pretty significantly from its first go-round. Additionally, as Harper previously mentioned, the contestant who goes home each week is the one who loses the lowest percentage of weight loss, not someone voted out by his or her team. And temptation challenges — both on campus when contestants were previously put in a room with high-fat foods, as well as when everyone was sent home for a week and asked to try to maintain their new routines in their old environments — have been eliminated from the show altogether.

“I was really happy to hear that it wasn’t about the temptations anymore, and it wasn’t about the vote-off. It’s very story-driven and there’s a lot of focus on the stories of each contestant,” says Harper. “There’s so many other kind of victories you’re going to see on the show that don’t relate to the scale. And having those talks about, ‘This is what it’s going to be like when you go home’ and ‘The people around you will not have been where you have been,’ and teaching them to be able to ask for what they need, I think that’s one of the biggest lessons to learn when it’s time for them to go home.”

The focus is shifted to balance the physical and mental health of the contestants more than ever before because of how closely tied those elements are with a person’s weight. For some, response to trauma, stress or sadness is to comfort themselves with food. By putting that front and center on the show, the audience watching at home will likely be able to see pieces of their own story reflected and come to more of an understanding about the cause and effect of unhealthy coping mechanisms.

“We have a contestant on the show that really went through a lot of struggles with his mother, who was dealing with drug an alcohol addiction,” Harper previews. “And at one point I was really talking to him about what it was like for him as a kid growing up in a situation like that — and this is a guy who was trying to come to grips with the emotional struggles that he went through and how all of his weight was because of what was going on in his childhood — and he looked at me in this one moment and he said, ‘I’ve gone through thick and thin with my mother, mostly thick.’ That just blew me away. It was so simple and so eloquent.”

Executive producer Georgie Hurford-Jones, who is also now executive vice president of current programming at Universal Television Alternative Studio, says that a big focus in casting the new season of “The Biggest Loser” was to vet that those applying were people who “wanted to be there for the right reasons.” But even when the team felt strongly that they did and chose them to compete, they couldn’t force anyone into “doing what we needed them to do.” When it came to the contestants’ willingness to share the most painful and emotional parts of their stories with each other, Harper and ultimately the American public, Hurford-Jones says it was Harper himself who inspired a lot of the response.

“Having gone through a heart attack and learning to get his fitness back, he had more empathy for what they were going through than ever,” she says. “When they find themselves with like-minded people — with support groups in general, you find comfort in other people — they became like a little family.”

When Harper considers why contestants opened up to him, he says it’s because he has “always been an inquisitive person and, working in the health industry for as long as I have, I’ve gotten to where I know the questions to ask and feeling it out.” He feels the most important thing is to “let that room breathe” and give everyone “the opportunity to say whatever it is they’re feeling. I think the biggest thing is getting people to open up within themselves — to get all the voices in their head out in a room of like-minded people.”

After the contestants shared their story in the support group setting, it was up to them how much they wanted to share with their trainer, Harper admits. But even if the trainers didn’t have the full picture of the contestant’s struggles, they were tailoring routines per person, adds Hurford-Jones.

“A lot of people who have problems with their weight to that extent are hiding — it’s a mask. You can’t just do a blanket, ‘Here’s this diet’ — and we avoided the word diet anyway, and assessed everyone individually,” she explains. “Everybody had a moment and we were careful to make sure to celebrate everybody’s progress, whether it be on the scale or off the scale. We really wanted to focus on mind, fitness and fuel.”

Harper joined the contestants during their weekly fitness challenges this season, too, although on the sidelines as the host, cheering them on and calling out their progress. The first challenge was a simple one: run a mile. But by Week 2, contestants were asked to flip semi-trailer size tires out of a mud pit to a finish line.

“These challenges were really without all the bells and whistles, but there were such victories and how good does that feel?” Harper says. “We’re getting people to things they’ve never done before, whether it’s sitting and talking about something hard, or in the physical challenges. You’d be surprised just how quickly you can adapt, and the teamwork that was involved in that, I found really uplifting.”

“The Biggest Loser” premieres Jan. 28 on USA.