Passage 2 Eat Less, Live Longer? 033
少吃能长寿？ 《新闻周刊》 2009-7-10

[00:00]Eat Less, Live Longer?
[00:04]Bob Cavanaugh smokes five cigars a day.
[00:09]He typically displays a mighty brown skin
[00:13]and has a sweet tooth the size of Montana.
[00:17]These aren't the typical characteristics of a 61-year-old
[00:22]who plans to live to be 120, but Cavanaugh has a secret weapon:
[00:29]he practices severe calorie restriction. Caloric restriction may extend lives.
[00:38]Is it worth it?
[00:40]Medical Marvel
[00:42]For years there has been evidence
[00:45]that a diet extremely low in calories extends the life span of species
[00:51]from mice to monkeys
[00:53](and a recent study confirms positive results for humans on this type of diet too),
[01:01]and the more we learn about caloric restriction,
[01:05]the more it appears to be something of a medical marvel: this week,
[01:10]a study in the journal Science shows that monkeys on a 20-year
[01:16]calorie-restricted diet not only lived longer,
[01:20]but had younger brains and fewer age-related diseases
[01:25]than the monkeys that ate a regular diet.
[01:28]But is it possible to eat a low-calorie diet and not lose your mind?
[01:34]Cavanaugh says yes.
[01:36]Yes, the diet is by definition restrictive
[01:40](thought practitioners simply call it CR).
[01:44]Calorie Consumption
[01:46]Men consume 1,800 calories, rather than the recommended 2,500;
[01:54]women eat only 1,500 to 1,700 calories per day,
[02:01]compared with the recommended national average of 2,000.
[02:06]But that doesn't mean they don't eat well.
[02:10]Cavanaugh’s Breakfast
[02:13]On a recent morning, Cavanaugh, who lives in coastal North Carolina,
[02:19]prepared his breakfast,
[02:21]the same one he has had most days
[02:24]since starting the calorie-restrictive diet eight years ago: a cup of oatmeal,
[02:31]powdered skim milk, and liquid skim milk. After two minutes in the microwave,
[02:37]he topped the mixture with half a cup of frozen blueberries—
[02:42]to provide antioxidants and improve mental freshness—
[02:46]and two tablespoons of sunflower seeds
[02:50]that will fulfill 60 percent of his daily vitamin E requirements.
[02:55]He washes down his 451-calorie breakfast with a cup of coffee.
[03:02]He won't eat again until dinner and claims he won't be hungry until then.
[03:08]"My breakfast gives me more than half my nutrition for the day,
[03:13]" says Cavanaugh, whose pre–calorie restrictive food included bacon and eggs,
[03:19]hot dogs, chips, and small bread roll. "It's so filling,
[03:24]I just don't get hungry for lunch."
[03:27]Cavanaugh’s Positive Physical Results
[03:30]A retired Marine who stands 5 feet 10 inches tall,
[03:36]Cavanaugh has seen positive physical results
[03:39]since he scaled back his calorie intake. Prior to starting the diet,
[03:45]he weighed 178 pounds, had a body mass index of 26
[03:51](an ideal BMI falls between 18.5 and 24.9),
[03:57]and his cholesterol  level was 273 (the ideal is less than 200).
[04:05]Five months into his new lifestyle, Cavanaugh's cholesterol dropped 103 points,
[04:12]and his triglycerides dropped from 145 to 63 (a healthy number is 150 or below).
[04:22]Now 140 pounds, he claims he hasn't had a cold in eight years,
[04:29]and the chronic diseases he suffered
[04:32]since his time in the Marines has disappeared completely.
[04:36]His energy levels have skyrocketed. "Remember when you were a kid
[04:42]and you would suddenly just take off running across the yard
[04:46]because of the exhilaration of energy? That exhilaration came back to me,
[04:53]" Cavanaugh says. "I haven't felt like this since I was a teenager playing football."
[05:00]Benefits of a Calorie-restricted Diet
[05:05]The benefits of a calorie-restricted diet were first seen in 1934
[05:11]when a group of researchers at Cornell University observed
[05:15]that the lives of rats extended by 33 percent when the rats'
[05:20]calorie intake was restricted. Results were first seen in humans almost by accident.
[05:28]In 1991 eight scientists entered a man-made,
[05:35]materially closed ecological system in Tucson, Arizona,
[05:40]known as Biosphere 2 to study man's influence on the ecosystem.
[05:45]The biosphere was unable to produce as much food as the scientists
[05:52]had predicted, forcing the researchers onto a nutrient-packed,
[05:57]extremely low-calorie diet. Roy Walford, the group's physician
[06:03]and an expert in calorie restriction and aging, noted that despite weight loss,
[06:10]the group's mental and physical activity levels were excellent;
[06:16]their blood pressures and cholesterol levels dropped.
[06:20]A 2004 study published in the Proceedings of the National Academy of Sciences
[06:28]detailed the results of humans who have practiced the calorie-
[06:32]restriction diet for a long period of time.
[06:36]The study's subjects had lower risk factors in heart and blood vessels
[06:43]and extremely high levels of HDL (or "good" cholesterol),
[06:49]and triglyceride levels were comparable to or lower than Americans in their 20s,
[06:56]despite the fact that all the study's participants were between the ages of 35 and 82.
[07:05]Mechanisms
[07:06]Still, the mechanisms behind the diet's success are still unknown.
[07:12]One general theory is that the diet puts the body into survival mode,
[07:17]causing cells to be extremely efficient, boosting the process
[07:22]by which cells remove damage. Research has shown that these unrecycled
[07:27]or damaged cellular components can lead to age-related decline.
[07:34]Caution
[07:36]Despite the positive results of this study,
[07:40]caution is advised before jumping into the CR diet.
[07:44]"You need to make sure you do things properly," says Bonnie Taub-Dix,
[07:50]registered dietitian and national spokesperson for the American Dietetic Association,
[07:57]who says issues of malnutrition are a concern. "Even then,
[08:02]it's not a guarantee of living longer. Some people eat poor diets
[08:08]and have great genetics; others take good care of themselves
[08:13]but have poor genetics. One plus one doesn't always equal two."
[08:19]Cavanaugh’s Dinner
[08:22]Although Cavanaugh is very careful about his nutritional intake,
[08:28]he'll occasionally give in to his sweet tooth,
[08:31]or he and his wife will have dinner out—though he says a steak,
[08:36]which he occasionally enjoys, "just tears my stomach up"
[08:40]due to the high fat content. He still eats birthday cake (400 calories)
[08:46]at his grandchildren's parties, a glass of red wine (124 calories) with dinner
[08:52]"six nights out of seven," and every Thursday he can be found sipping a beer
[08:58]with his friends down at the local cigar bar.
[09:01]The rest of the time, dinner typically consists of a small portion of lean meat,
[09:08]chicken or fish; a big salad; and fruit for dessert.
[09:12]After, Cavanaugh eats his two daily canned sea food to supply the zinc
[09:17]and copper he needs and a handful of nuts, including two Brazil nuts
[09:23]to provide some other elements.
[09:26]Cavanaugh’s Goal
[09:29]Then he and his wife head to the porch. They smoke and watch the sunset.
[09:34]"I used to think about life as being on a conveyor belt.
[09:39]You got on and traveled to the end, then died.
[09:42]But when I got into learning more about CR, it changed my whole outlook on life,
[09:48]" he says. "I still see it as a conveyor belt,
[09:52]but now I know that I can regulate the speed of it.
[09:55]I can slow it down. Living to be 100 is now a definite goal."