By Jessica Herndon
Updated February 14, 2011 12:00 PM

For Olympic gold medalist Rulon Gardner, being inducted into the Wrestling Hall of Fame last June was a high point in his career. That was quickly followed by one of the lowest moments in his life: When he caught a glimpse of himself on TV later that night, “I was like, ‘I’m so large!'” recalls Gardner. “That was my wake-up call. I didn’t recognize myself. I looked like a guy who had never been an athlete.”

More than just an athlete, Gardner, 39, became an instant American icon at the 2000 Sydney Olympics, where the underdog from Wyoming pinned his undefeated Russian opponent to win gold in Greco-Roman wrestling. After retiring in 2004, “I stopped exercising but still consumed a massive amount of calories,” says the 6’1″ Gardner, whose waistline expanded from 36 in. to a whopping 52 in. “The embarrassing part was my body was changing but when I looked in the mirror, I thought, ‘I’m still in shape.'”

Now Gardner has stepped into a new arena for the fight of his life: The former super-heavyweight wrestler has been competing on The Biggest Loser: Couples alongside Justin Page, 39, co-owner of their health club Elite Training Center. “I’m going to make an extreme change!” says Gardner, who has lost 80 lbs. thus far and earned the reputation of being the passionate motivator of the group. “I don’t need to train to be an athlete. I need to train to be a human.”

When he walked away from wrestling, Gardner didn’t want to train for anything. “I thought I would give myself six months to step away. Then it was a year. Then three,” says Gardner, who continued to eat 1,200-calorie protein-packed dinners. He would then indulge in late-night burger runs and load up on candy bars. And he never doubted his ability to get back on track: After surviving a snowmobile accident that led to an amputated toe in 2002 and a motorcycle accident in 2004, Gardner felt “my body would never let me down.”

But as he faced mounting financial troubles with his business, Gardner-who went through an emotional split from his first wife, Stacy, in 2001-ate his way through stress. “Food would make me feel better,” says Gardner, who tried quick fixes like saunas and fad diets to no avail. Soon “I couldn’t get on a treadmill and walk more than a minute without breathing heavy.”

He finally realized he needed help when his sister Jerry, a cardiologist, named all the health risks associated with obesity including sleep apnea and high blood pressure. Says Gardner: “I was a time bomb.”

When he heard that Loser was rounding up contestants for the ranch, Gardner quickly signed up with the encouragement of his wife, Kamie, 28, whom he wed in ’08. “If I tried to do it myself, it would take me two or three years,” says Gardner, who now eats salads and seven-grain bread and works out seven days a week on Loser. “I want to live another 40 years. It’s time to get my life back on track.”