Carson points to studies that show that calorie restriction followers have healthier glucose and insulin levels as they age, less incidence of inflammatory diseases and do better on cognitive function tests.
"There's something to this idea that getting just the right amount of calories for survival is an important way to manage health," she says. "They find that place where they eat just enough, somewhere between 1,300 and 1,500 calories a day. The body is remarkable in how it adjusts and tries to maintain a steady state to keep you alive and functioning."
MARK GRAHAM
MARK GRAHAM
Calorie restriction works in the lower
organisms, we know, Bauer says.
But with humans its anybodys guess so far.
Closed Location
Related Content
More About
The few calorie restriction studies using human subjects involved people voluntarily on the diet already, including one project at the Washington University School of Medicine looking at heart health among several groups, including 28 members of the Calorie Restriction Society who had been eating a CR diet for six years. The CR followers' hearts were more elastic and able to relax better between beats compared to subjects who ate a standard Western diet and did endurance exercise training. That study concluded that leanness helped prevent disease, but only calorie reduction slowed down aging.
The most recent short-term study on CR, conducted at the University of Munster in Germany and published online in January by the National Academy of Sciences, lasted three months and determined that reducing calorie intake by 30 percent improved memory ability by 20 percent in elderly individuals (average age 60.5 years).
Evidence keeps mounting showing the many positive effects of eating less. But is a lifetime of meager meals a guarantee of long life?
The skunk at the calorie restrictors' picnic is longevity expert Steven Austad, Ph.D., author of the book Why We Age and professor of biology at University of Texas Health Science Center at San Antonio. He doesn't believe that either CR or resveratrol will have as much of a "youthening" effect on humans as they do on lab animals. As he's told several conventions of the Calorie Restriction Society in the past, what works on flies and mice fails seven out of 10 times on people.
"We know that CR extends life in some animals, in some it doesn't," Austad says. "Some kinds of mice it works, some it doesn't. Some fruit flies it does, some it doesn't. People who study this tend to forget the experiments in which it didn't work."
Austad says he warns extreme calorie restrictors that "the jury is still out" on whether eating so little will add healthy years. "It might suppress the immune system and you could die from the next flu epidemic," he says. Or you could end up at 80 with muscles too weak to support even a thin body. "It would be extremely interesting and exciting if reducing your food intake would extend your life. But people in the aging community tend to jump on the bandwagon and make the leap from fruit flies to humans a little too enthusiastically."
And resveratrol? "Vastly overstated," Austad maintains. "Resveratrol has never been shown to extend life in any mammal except one—lab mice—eating so much fat that it was like you and I ate nothing but Big Macs every day. Other studies on mice eating a normal diet, resveratrol had no impact on how long they lived. It's an intriguing drug, but we don't have any evidence that it really does anything."
Nature and genetics play a much stronger role in longevity than diet, says Austad. In his research, he's interviewed dozens of people who lived to 100 or beyond. "The ranks of 100-year-olds are not populated by marathon runners," he says. "They didn't exercise. Some smoked for 95 years. They've got a genetic quirk."
Though he believes the first person to live to be 150 is already alive, Austad, 52, isn't hedging his own bets on the actuarial tables. He exercises "fairly fanatically" and doesn't smoke, but he also indulges in the occasional cocktail and he doesn't count calories.
"Here's an interesting thing—I've been to several meetings now of scientists who study calorie restriction, and I look around the room and don't see gaunt, skinny people," Austad says. "Some are slender, some are obese, some are muscular. If you look at those people who spend their lives [studying] CR, very few of them seem to do it themselves."
Back in the humid fruit fly chamber at SMU, Dr. Johannes Bauer laughs when asked if he practices calorie restriction. At 5-foot-7-inches, 140 pounds, the German-born scientist (who looks about 19) never exercises, doesn't take resveratrol and has never been on a diet. "Humans evolved as omnivores. They ate everything in their path," he says.
----
Ben Franklin advised in Poor Richard's Almanac: "To lengthen thy life, lessen thy meals." Franklin lived into his 80s at a time when the average life expectancy for men was around 35. If he were around today, he might also advise eating more of thy meals raw.
At a recent potluck supper of the Our Heart of Dallas Radical Health Raw/Vegan Meetup, one of 10 raw food social groups in Dallas organized through Meetup.com, the dining table at host Amy Hirsch's apartment is crowded with uncooked edibles prepared by the 25 attendees (out of 237 members total). Shiny green chard leaves are wrapped around raw bits of cauliflower on one plate, and there's a container of pudding made from soaked hemp seeds and coconut milk. Fresh pineapple, blueberries, apples and other fruits brighten the spread. In the middle of the table sits a large bowl of something resembling wet hair. It's hijiki, a calcium-rich brown sea vegetable the "raw foodists," as they like to be called, eat like noodles.