Can you diet your way to longer life?
Joanne Vizziello has cut her food intake by a third in a study that looks at restricting calories to live longer.
A study tries to learn if calorie restriction can delay aging.
(CNN) -- Joanne Vizziello is searching for the fountain of youth, but not with facelifts or Botox. She's turning to her diet to help her live longer.
"I wanted to be a healthy, productive senior, and when I turned 40, I looked around and realized I was not on that path," she says.
An incident when an older woman passed her and her friend on a hiking trail was the last straw.
"We're on the side of the trail, huffing and puffing, and she passed us with her backpack going up the trail," Vizziello recalls. "I had to ask her, 'How old are you?' She was 70 years old and I said, 'I want to be that person. I want to be hiking up a trail when I'm 70 years old.'"
That's when Vizziello turned to a diet, inspired by past studies that looked at restricting calories to live longer.
Research on monkeys, rodents, fish and even insects has shown that if calories are cut below what the animal would normally choose to eat, they live longer.
"They don't just live longer, they are healthier," says Susan Roberts, a Tufts University professor and lead researcher of a current caloric restriction study in humans. "[The animals] actually aged biologically slower. Their hair has gone gray less quickly. Their hormones have stayed at their youthful profile and their immune function has stayed good."
Vizziello is hoping for the same results. She has joined Roberts' study in Boston, Massachusetts, to see if eating less can slow down aging in humans. The study is part of a larger national research project funded by the National Institute on Aging called CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy).
The theory of the research? With fewer calories, cells throughout the body appear to die more slowly and repair themselves more easily.
So now Vizziello has cut her calories by a third of what she normally eats in effort to feel younger -- and stronger. The menu changes daily, and for the first six months, every last morsel was weighed out to the precision of one-tenth of a gram, vacuum-packed and then sent home with the study participant. After nine months on the study diet, Vizziello is now allowed to cook her own low-calorie food.
More support that eating less means living longer is the theory that fat, especially around the stomach, can actually increase your chances of getting cancer or heart disease, leading to an early death.
"People think that fat is some kind of inert thing that just looks bad, but it's very active tissue that produces all kinds of bad things," says Dr. Tom Perls, author of "Living to 100" and founder of the New England Centenarian Study. "So it's probably good to have as little visceral fat as possible."
While Perls says that living to 100 is largely influenced by your genes, weight is also a factor to longevity in the centenarians he has studied.
"Whatever the underlying process, it does appear that caloric restriction is an important mechanism of slowing down the aging process," he says.
Research on fruit flies and rats has shown that a 30 percent reduction in calories can lead to 30 percent longer life, according to the National Institutes of Health.
But can people adjust to slashing a third of their food out of their life, especially in a nation where two-thirds of the adult population is overweight or obese?
"This is not a diet where diet equals starvation," says CALERIE participant Vizziello, who has lost 40 pounds in nine months. "This is eating the right foods and if you eat the right foods, you're not hungry."
Vizziello will stay on the diet for a year while researchers monitor aging indicators, such as levels of certain hormones, immune function and heart health.
Researcher Roberts says it's still too early to know whether people on the diet will actually live longer, or live healthier, but she thinks that they'll do both.
So is there a fountain of youth in eating less?
"I think there's a small fountain," Roberts says. "I think that by eating well we can do the best we can given the genes we've got."