It began with a challenge from his wife.

Mike Keller's doctor had been telling him for years that he needed to lose weight. He tipped the scale at 262 pounds. His blood pressure was rising, his cholesterol was elevated and his sugar levels were nearing the danger zone for diabetes.

But the South Hampton 53-year-old never took the warnings seriously.

Then last year, the spark was lit. Keller's wife heard about a "Biggest Loser" program at Latitude Sports Clubs. She dared him to sign up, sealing the deal with her offer to cover the cost.

"My father had a stroke when he was in his late 50s, early 60s," Keller said. "I finally broke down and decided it was time to do something about my health to prevent what could happen."

Less than a year later, Keller has dropped almost 100 pounds, and become a 169-pound pillar of health.

Keller credits the non-intimidating approach of the 12-week weight-loss program — Latitude's version of the hit TV show "The Biggest Loser" — and its team format for starting him on the road to success.

As part of the program at the region's Latitude clubs, teams of up to 10 participated in one-hour workouts twice a week with a trainer, who consulted with each participant on their individual nutrition and exercise routines. In between the group workouts, they exercised on their own. Unlike the TV show though, no one was kicked off for not meeting set goals, Keller said.

When Keller signed up at the Latitude's in Salisbury last December, Keller was surprised to discover that, according to the Body Mass Index charts, he was obese.

"I knew I was overweight, but at 5 feet 10 inches, I did not consider myself obese," he said. "But the numbers told a different story."

The first workouts were basic calisthenics routines, including jumping jacks, crunches, push-ups, running in place and planks, which Keller said was a "particularly torturous" exercise regimen for someone as out of shape as he was.

"I'm an electrical contractor — my work gives me quite a workout during the day, going up and down stairs and ladders, lifting things and installing," Keller said. "I didn't think I was that bad out of shape, but after the first hour-long workout, I could barely lift my arms above my head to wash my hair."

Despite the initial pain, the first weigh-in after the challenge started proved enough of a motivator to keep Keller going. He had lost 12 pounds in the first week.

Each week, as the club continued to track individual and team results, the numbers on the scale continued to drop for Keller. He averaged a weight loss of five to six pounds every week.

"In the group setting with peers, it was more motivation in that atmosphere than working out on your own — especially just getting started," Keller said. "And with each weigh-in came a new commitment to work harder, eat even healthier and live better."

By the end of the 12 weeks, Keller had dropped 68 pounds, ending the challenge at a slimmed down 194 pounds. While a 60-plus-year-old man at the Methuen club had lost 73 pounds, Keller won the challenge because he lost the most body mass, a total of 25.95 percent.

"In the previous year's challenge, the winner lost 48 pounds, and I remember looking up at her picture in the gym and thinking 'I couldn't lose that,'" Keller said.

Keller's initial goal was simply to lose some weight and complete the program. But halfway into the 12 weeks, he found he was reaping many other benefits. He brought his sugar, blood pressure and cholesterol levels down within normal, healthy ranges.

"The evidence was clearly noticeable — clothes started fitting better, then quickly became baggy as my body weight decreased," he said.

Keller, whose once 42-inch waist is down to a svelte 32 inches today, continued to work at it, losing additional weight after the challenge ended. He now goes to the gym on his own and keeps up with the nutrition program as well. Gone are the cravings for the snacks and fast food that were a regular part of his diet.

"When people used to ask what I missed most, my automatic response was 'Wendy's Number Two,'" Keller said. "But I don't have any more cravings now. I don't miss that type of food."

There's actually nothing Keller misses from his heavier days. He believes he could have been headed down a completely different road had he not signed up for the "Biggest Loser" program.

"Every day I look in the mirror, I can still remember that guy who used to stare back at me," Keller said. "It's been such a vast improvement."