The research included almost 1,900 people born in 1920 and 1921 who were assessed at ages 70, 78 and 85. Those who did less than four hours of physical activity per week were considered sedentary, while those who exercised about four hours a week, did vigorous activities such as swimming or jogging at least twice a week, or those who got regular physical activity (such as walking at least an hour a day) were considered physically active.

The researchers found that 53.4% of participants were physically active at age 70, 76.9% at age 77, and 64% at age 85. Compared to those who were sedentary, physically active people were 12% less likely to die between ages 70 and 78, 15% less likely to die between ages 78 and 85, and 17% less likely to die between ages 85 and 88.

Virtually everything American society has done for the past 100 years has made it easier for its people to be fatter, said James Sallis, a San Diego State University psychology professor, and others who gathered recently at the American College of Sports Medicine's annual meeting.

"We've built an unhealthy world in a lot of different ways," said Sallis, who was once dubbed an "obesity warrior" by Time magazine.

Sallis contends change will come only when the public demands walkable development, more federal money for parks and bike paths and even a tax on industries that promote sedentary lifestyles (he pointed to video game makers, movie theater chains and even electric Segway scooters).

Proof that people will accept an active lifestyle and walk to parks and shopping if they can is found in the "new urbanism" style of planned communities, the experts contend. They pointed to Denver's Stapleton neighborhood, an enclave of new homes built where the city's old airport used to be.

The neighborhood is a mix of shops, offices, parks, apartments and houses linked by wide sidewalks and meandering bike paths. Architecture varies from single-family homes to rows of brownstones. Tom Gleason, a spokesman for developer Forest City, said the design has been a hit.

"Visceral fat is very bad for you," says Richard N. Bergman, a professor at USC's Keck School of Medicine. "It seems to have a more negative outcome on health than overall fat."

The evidence now is so compelling that some experts suggest it's time to forget about scales and weight loss and focus on waists and "inch loss."

Luckily, visceral fat doesn't appear to be a particularly stubborn enemy. Health experts have discovered that consistent, moderate exercise by itself appears to help the body rid itself of vast amounts of deep abdominal fat — even when the scales show the pounds aren't dropping very fast.

This emerging science carries a message for consumers: Measure your waist circumference. And reduce it if need be. Doing something about that paunch could help save your life.

That is probably the best news about visceral fat: It's not all that hard to lose, and losing even a little might make a big difference in cardiovascular health. Sit-ups and liposuction won't work (sit-ups merely tighten the muscle and liposuction only removes subcutaneous fat), but studies show that regular diet and exercise can lead to a substantial drop. "It's easier than reducing any other fat because the abdominal fat is metabolically very active," Sharma of McMaster University says.

In fact, studies show that people who lose only 10% to 15% of total body weight can still lose up to 30% of their visceral fat — and reap fast, important benefits. A 2001 study published in the American Journal of Clinical Nutrition showed that white and black women on a diet-and-exercise program lost 41% and 37% of their visceral fat, respectively, with a total weight loss of about 15%.

Frame is 97 and Sykes is 98.

''I didn't do any exercising ever until I came here," said Sykes, hard at work on the Nu-Step cycling machine. ''The wonderful thing is it makes me feel better. I think it's why I'm still around."

At Dartmouth College a lifetime ago, he played for the tennis team and later in life he was a golfer at the Duxbury Yacht Club. ''But I don't play golf anymore because I can't see where the ball goes."

Frame says the workouts allowed him to regain his strength after heart surgery. And with the strength came a freedom. ''If I wasn't strong enough, I would have had to move into an assisted living situation. Working out has kept me more independent."

But do not ever say these fitness enthusiasts are doing well ''for their age." Just say they are doing well, no matter what their age.

Just 132 of the people surveyed said they practiced yoga regularly for at least four years. However, overweight yoga practitioners lost about 5 pounds on average during the 10-year period, while those who did not practice yoga gained an average of 13.5 pounds. People who were normal-weight and regularly practiced yoga gained three fewer pounds during this period of life than those who didn't do yoga (9.5 pounds compared to 12.6 pounds).

Dr. Janine Blackman, the medical director of the University of Maryland Center for Integrative Medicine, has another theory: the "mindful" nature of yoga creates a healthier response to stress, which in turn prevents stress-driven eating and lowers stress hormones.

"Middle age is a full time in life," she said. "A better response to this stress can lower cortisol and other stress hormones, which helps physiologically. If cortisol is elevated, you're more likely to have Insulin resistance, which is central to obesity."