01/04/2010 AT 12:00 AM EST
It turns out that tough-love trainer Jillian Michaels
has a softer side -- and it includes genuine concern for the medical safety of the contestants on The Biggest Loser
"The contestants keep getting bigger and bigger," Michaels tells Ladies' Home Journal
in its February issue. "As the trainers we have no say over the challenges. We worry about them too."
Executive producer Todd A. Nelson says, "We all worry," but adds that the show is learning how to safely manage the medical conditions of the heaviest contestants, "and this allows us to fine-tune the process and reach out to a heavier population."
Michaels says she loves the show, which returns Tuesday (8 p.m. EST) to NBC with its biggest edition ever
, but that it's a whole lot more work than anyone sees on TV. "You never see what's going on in its entirety," she says. "For every 10 minutes we're on the show, acting like insane , there are a hundred hours of training you don't see. The stretching, the icing. Nobody wants to watch that."
The 35-year-old fitness guru has come a long way since her days as an overweight and angry teenager. "I lived on junk food," she tells the magazine. "I had no direction. Once I punched a hole in our wall. Another time I stole a car."
In the end, she turned to exercise as a way to repair both her physical and emotional self. "I'm passionate about helping rebuild their lives," she says. "When someone feels strong physically, they feel strong in every aspect of their existence. If they have endurance and achieve in the gym, then I can redefine their entire self image. I can wipe away years of negativity." --Tim Nudd
Ladies' Home Journal