Eating Less to Live Longer

For Darren and Shannon Vyff, dinner is family time. But Shannon's is a very different meal. In fact, it's her breakfast and lunch too — it's the only food she eats all day.

Vyff consumes 1,600 calories a day, about one-third less than most American women consume. This has helped her lose 85 pounds after the birth of her third child.

Yes, it's a diet. But the 28-year-old Oregonian isn't severely cutting calories to get a movie-star body. She doing it in the hope that she'll add years to her life.

"I'm hoping this will extend my life to a time where science has eradicated the greatest killer, which is aging," she said.

Can your diet slow the aging process and help you stay young forever? That's the theory behind Calorie Restriction, or CR, a phenomenon practiced by an estimated 1,000 individuals around the world 3 cut food drastically, keep the nutrients in your diet, and live longer.

Going Easy on Your 'Engine'

Dr. David Katz of Yale University, an expert in chronic disease prevention through nutrition, compares the CR regime to not pushing your car too hard.

"If you think of putting lots and lots of fuel into a car because you're driving it fast and hard, you're going to wear out the parts," Katz said, "Well, there really is a wear and tear price to pay for burning fuel in the human body as well."

Katz says if we get by on less fuel, or food, we'll be less apt to wear out our bodies, and, he says, "potentially add decades at the far end of the life span."

Back in 1988, when ABC News first reported on CR, we met with Dr. Roy Walford of the University of California, Los Angeles. He was working with lab mice, which he had placed on a special low-calorie, high-nutrient diet. The mice lost weight and outlived their companions by more than 50 percent.

"If the translation is direct," Walford told ABC News, "as from mouse to man, then we could live to be 175."

Paul McGlothin, who's been practicing CR for about 10 years, hopes Walford is right. "I'd love it if I could be over 100 and jumping around and playing basketball," he said.

McGlothin convinced his wife, Averill, to join him in giving up calories to live longer. They eagerly recite their daily diet: 1,400 calories for her, 1,800 for him; their dietary delicacies include lemon juice and water to sweet potatoes and fruit; and Averill's favorite, "rice protein" breakfast.

McGlothin, who's 5 feet 11 inches tall, weighs in at 131 pounds. He lost 29 pounds on CR. His cholesterol, blood pressure and body temperature have all dropped to lizard-like levels. And yes, McGlothin says he gets hungry. The odd thing is, he's happy to be hungry.

"To me, it is not a fearsome thing," he said. "It's a feeling of joy knowing I've accomplished my goal for that day."

Paul and Averill, like many CR devotees, exercise regularly. It's all part of the routine to reach that elusive goal — staving off old age.

"I love my life. I love my work. If I could continue doing this for the unforeseeable future, it would be wonderful," Paul McGlothin said.

He acknowledges that may not be a realistic goal. It's just something he says he's hoping for.

But it may take another century to find out if CR really will create a bunch of centenarians.

Dr. James Greenberg, who teaches nutrition and health at Brooklyn College in New York, says that since good scientific studies would have to follow subjects for their entire lives, we might not know until 2013 if the diet works. He is practicing what he preaches, and has been on CR himself for 11 years. But his wife wasn't too thrilled about it when he began the strict regime.

"She was very unhappy in the beginning," he said, "Because I got very thin and she looked at me and said, 'You look like a concentration camp survivor. It's either me, or your diet.' I chose her. I increased the number of calories I was eating, put on a little bit of weight. We're still together."

So is it fair to say this diet is a little weird? Greenberg says yes.

That is also the judgment of physicians like Katz, who is not on the diet and does not recommend it.

"I truly believe that most people trying to do this — even if they do live a long time — would regret an awful lot of it. It's unpleasant. Food is fun. Food tastes good," he said.

"They're at the fringe of … of dietary behavior," Katz said. "So, even if it works, yeah, it's a little wacko. For most of us, it's a little wacko."

Katz also says the quest for eternal youth can be fraught with dangers if a CR diet is not properly balanced. Likely consequences include osteoporosis, anemia and damage to blood cells and the skin.

If a young woman came into his office and said she was going on CR, Katz says, he'd try to talk her out of it. "It's an extreme approach and if she's really concerned about weight control, that's not what CR is about."

It's also not about dieting your way into a 25-year-old body. Shannon Vyff knows she can't turn back the clock, but she can plan for a better future.

"You want to be healthier in your 40s and 50s. You don't want the knee problems or as much sagging," she said. "I mean, you just, want to stay and extend your middle age for a long time before you start actually aging more severely."

Even if it means giving up tastes the rest of us live for right now.