Like a lot of folks in the ATX100 program, Becky Helton cringes at the thought of a gym crawling with buff bodies or packs of wispy runners capable of sprinting a 5K without panting.

Amid the group charging up the sloped sidewalk in front of the Long Center on a recent night, though, she's perfectly comfortable.

"It's a group of people who are my size, who are all doing fitness," said Helton, 47. "I've done other groups, and I'm always the slow, fat one. Here, I'm not the slow, fat one."

Everyone in this program, sponsored by the RunTex Foundation, joined knowing he or she needed to lose 100 pounds or more. Their common goal: to improve their conditioning so they can live a more active life, without the intimidation of trying to exercise with super-fit people.

Out on the sidewalk, some zip along. Others can barely walk.

There are no weigh-ins, just exercise, camaraderie and support.

That doesn't mean they're not losing weight. Many of them are. They're getting kudos from their doctors for their improved health, too.

Tonight, the members walk a loop backward up the sidewalk, their hands raised overhead. They do another lap side stepping, one raising their knees high and one more kicking their feet up behind them as they go.

The ATX100 program began in September. A month later, RunTex store owner Paul Carrozza added a second group, ATX50, geared to people who are 50 pounds overweight. Soon, an ATX20 group was created, then ATXKids. An ATXSenior group is now in the works, along with an ATXMoms group.

Participants in ATX100 pay $100 for a yearlong membership, which includes a pair of running shoes. Groups meet for workouts three times a week. Saturday sessions include a free lunch from My Fit Foods and lectures on everything from nutrition to psychology. Members can attend a weekly yoga class, too.

So far, more than 200 people have joined, said James Russell, executive director of the RunTex Foundation and leader of the program.

Workouts consist of walking and drills, done as a group, with some jogging thrown in for those who are ready for it. It's all about slowly and deliberately gaining conditioning without overtaxing participants.

"It's bringing the body out of hibernation," Carrozza said.

"To me, life is lived in motion," he said. He wants to give others a chance to live that way, too.

At the same time, he understands that it's far more difficult for an overweight person to exercise than someone like him, who is already in shape. It's also why Russell, who's fit and wiry, occasionally puts on 100 pounds in body weights and joins the workouts. His parents are members of the group, too.

Unlike many fitness programs, which culminate with a walk or race, the ATX programs are ongoing, with 5K events along the way to keep members focused. Carrozza said he's found that if a fitness group focuses on a single race, members sometimes quit exercising when they've reached that goal.

Physician Yale Pearlson, 52, joined two months ago. He wants to walk better.

"I've learned basically it's just a matter of trying," he said. "Increased mobility will come if you make an effort."

He likes being part of a group of people working toward the same thing, versus "going to a gym where everyone is buff and looking gorgeous. These are normal-looking people."

Each group has a private Facebook page, where members share photos, encourage each other to sign up for such events as the Tiara 5K Run and the Statesman Capitol 10,000, and grumble a little bit about a hill on Seventh Street, dubbed Mount Hillamanjaro, where they sometimes work out.

"I like that everybody here looks like me," said attorney Gina McCauley, 36. "I'm not the oddball. It's not out of reach. And it's fun."

Her goal is to get down to a 15-minute mile. Even better, she'd like to be able to run an entire 5K without walking.

"You don't work as hard if you're by yourself," said Kelly Broadaway, 45, who has signed up for the Tiara 5K. "I would never have done a 5K. Are you kidding? I'm too fat."

Tonight, the group wraps up the hourlong workout, set against the backdrop of a glowing Austin skyline, by doing five laps — a mile — around a nearby pond for time.

The first finishers roll in, sweaty, after 9½ minutes. The rest trickle in over the next 7 minutes, some jogging, some walking. As each one finishes, a cheer goes up.

"Did you see me jog that last part?" Helton hollers excitedly as she finishes. That, she notes, from a woman who did everything she could to get out of PE class as a kid.

She's no longer scheming to miss class. She's found her fitness home, and it feels good.

pleblanc@statesman.com; 445-3994