Dieters Eat Less to Live Longer
Joanna Glasner 08.25.05 | 2:00 AM
Lisa Walford considers her current weight of 82 pounds to be just about optimal.
Granted, it's not easy to maintain. For much of her adult life, Walford, a petite 4'11", hovered around 95 pounds. Sustaining her new weight requires consuming only about 1,300 calories on most days, 15 percent less than what she used to eat.
But 50-year-old Walford, who admits her appearance could be considered gaunt, says the health benefits of her diet make it worth following. As a devotee of a diet movement called caloric restriction, or CR, she believes that consuming less will allow her to live longer. It's a notion she learned from her father, CR pioneer Roy Walford, and one she's comfortable sharing with a national audience.
"I was on Good Morning America, and Diane Sawyer said 'You look so thin. Are you really healthy?'" recalled Walford, who made media rounds this summer to promote her new book The Longevity Diet, co-authored with fellow CR practitioner Brian Delaney. Her response to such queries, she said, is usually the same: "We tend to associate health with external cosmetics, but I tend to think of the internal cosmetics.... People on CR are very internally healthy."
With the oldest members of the baby boomer generation about to turn 60, demographic trend watchers aren't surprised to see a rise in interest surrounding diet and health pursuits associated with extending life expectancy.
Myriad diet books on the market promise age-reversing effects through such techniques as copying the culinary habits of Okinawans, studying one's DNA or downing voluminous amounts of supplements and eating plenty of fruits and veggies. But caloric restriction, an age-extending technique that has been shown to work quite well on mice and other organisms, is an increasingly popular option.
Walford estimates that more than 2,500 people currently belong to one of two popular online CR forums, the Caloric Restriction Society and the CR Support Group e-mail list. Message-board topics range from a study linking Alzheimer's disease and insulin levels to the health effects of a caveman-style "paleo" diet, to the question of whether it's important to eat breakfast even if one isn't hungry in the morning.
Eating guidelines are also abundant. Since CR practitioners eat few calories, adherents believe it's necessary to pack as many nutrients into their meals as possible and to avoid starchy, processed foods. One menu representative of a typical 1,500-calorie meal plan features foods like salmon, egg whites, nonfat yogurt and vegetables.
CR fans say the emphasis on nutrition and the fact that they pursue the diet for health reasons makes it quite different from eating disorders like anorexia nervosa, which stem from a fixation on body image.
But Merryl Bear, director of the Canadian National Eating Disorder Information Center, says many people who talk about going on diets for health reasons are actually using such arguments to legitimize unhealthy fixations about food and weight.
"Some individuals who have eating disorders may use this theory as a way of justifying their food and weight preoccupation," Bear said.
Another argument against rigorous calorie-cutting is a lack of long-term studies indicating whether CR is linked to significantly longer human life spans.
Aubrey de Grey, a Cambridge University gerontologist, recently wrote a paper (.pdf) concluding that CR is unlikely to add more than two or three years to the mean or maximum life span. De Grey said he is skeptical of CR's potential for radical life extension in part because he sees no reason why it would be advantageous from an evolutionary perspective.
"Basically, there has been insufficient selective pressure for us to retain the ability to live 20 years longer than normal in response to nutrient deprivation," he wrote in an e-mail. De Grey added that he has no objection to moderate CR for health reasons, so long as practitioners don't expect to live a few decades longer as a result.
But moderate health benefits hardly seem to justify the effort of a CR diet, noted one contributor on the website Fight Aging, who wrote:
"What a trade-off: Feeling hungry your whole 80+3 years, or just enjoy your meals and die at 80."
Not even ardent CR supporters can accurately estimate how many years the diet might add to their lives, but most CR followers believe the diet offers potential for life extension much greater than two or three years.
Studies of mice, worms and other animals fed a restricted-calorie diet support the notion of radical life-extending benefits. A study of Labrador retrievers published in 2002 also found that a 25 percent restriction in food intake increased median life span and delayed the onset of signs of chronic disease in the dogs.
For humans, Walford prefers a more moderate regimen, in which people reduce caloric intake about 13 to 15 percent from their baseline level. The baseline is different for each person, based on the number of calories required to sustain a stable weight when one is neither undereating nor overeating.
As in all forms of dieting, however, there are people who take CR to an extreme. Walford said she does not advocate "serious CR," in which calories are reduced by around 30 percent, often with harmful effects.
"We do have people who have gone to the outer limit, where their body literally starts to metabolize their own organ meat," she said. "But that's serious CR, and all the media sensationalizes that part ... and then people discard the benefits (of moderate CR.)"
source: http://www.wired.com
donderdag 29 november 2007
Calorie-Starved Rats Live Longer:
Calorie-Starved Rats Live Longer: Study
But most humans couldn't maintain such a low-cal diet, scientists say
Posted 11/2/07
FRIDAY, Nov. 2 (HealthDay News) -- Cutting back drastically on daily calorie intake can lead to longer life, at least in rats, say University at Buffalo researchers.
They speculate that this kind of diet can help maintain physical fitness into old age, slowing the progression to disability.
A lifelong 40 percent calorie-restricted diet reduced the rats' amount of visceral fat, which expresses inflammatory factors -- proteins that, in humans, cause chronic disease and an age-related decline in physical performance and vitality, the research team reported.
"This is the first study to report that caloric restriction reduced production in visceral fat of the inflammatory cytokine IL-6 and enhanced performance on overall physical function assessments," principal investigator Tongjian You, assistant professor of exercise and nutrition sciences in the UB School of Public Health and Health Professions, said in a prepared statement.
"In additions, rats that ate a normal diet lost a significant amount of lean muscle mass and acquired more fat, while calorie-restricted rats maintained lean muscle mass as they aged," You said.
The study was published in the October issue of Journals of Gerontology Series A: Biological Sciences and Medical Sciences.
While this severely-restricted diet proved beneficial in rats, You noted that people could not adhere to such a strict diet.
"Based on an average of 2,000 calories per day for adult women and 2,500 for men, cutting by 40 percent would mean surviving on 1,200 and 1,500 calories per day, respectively," You said. "It's very difficult for people to maintain that type of diet for short periods of time, and it would be nearly impossible over a lifetime, while staying healthy. Starting on a diet like that in the senior years would be harmful.
However, a more moderate 8 percent caloric restriction is achievable in people and may have a positive effect, recent research suggests.
More information
The MedlinePlus Medical Encyclopedia has more about calories.
Copyright © 2007 ScoutNews, LLC. All rights reserved.
But most humans couldn't maintain such a low-cal diet, scientists say
Posted 11/2/07
FRIDAY, Nov. 2 (HealthDay News) -- Cutting back drastically on daily calorie intake can lead to longer life, at least in rats, say University at Buffalo researchers.
They speculate that this kind of diet can help maintain physical fitness into old age, slowing the progression to disability.
A lifelong 40 percent calorie-restricted diet reduced the rats' amount of visceral fat, which expresses inflammatory factors -- proteins that, in humans, cause chronic disease and an age-related decline in physical performance and vitality, the research team reported.
"This is the first study to report that caloric restriction reduced production in visceral fat of the inflammatory cytokine IL-6 and enhanced performance on overall physical function assessments," principal investigator Tongjian You, assistant professor of exercise and nutrition sciences in the UB School of Public Health and Health Professions, said in a prepared statement.
"In additions, rats that ate a normal diet lost a significant amount of lean muscle mass and acquired more fat, while calorie-restricted rats maintained lean muscle mass as they aged," You said.
The study was published in the October issue of Journals of Gerontology Series A: Biological Sciences and Medical Sciences.
While this severely-restricted diet proved beneficial in rats, You noted that people could not adhere to such a strict diet.
"Based on an average of 2,000 calories per day for adult women and 2,500 for men, cutting by 40 percent would mean surviving on 1,200 and 1,500 calories per day, respectively," You said. "It's very difficult for people to maintain that type of diet for short periods of time, and it would be nearly impossible over a lifetime, while staying healthy. Starting on a diet like that in the senior years would be harmful.
However, a more moderate 8 percent caloric restriction is achievable in people and may have a positive effect, recent research suggests.
More information
The MedlinePlus Medical Encyclopedia has more about calories.
Copyright © 2007 ScoutNews, LLC. All rights reserved.
All species experience aging
All species experience aging
Senior Health By Clark Gillespie
According to an African legend, God sent a scavenging bird called a Halawaka out into the world with instructions for our endless self-renewal. The instructions were simple – as age crept upon us, we simple shed our skin and emerged refreshed and new. On its journey, however, the unreliant and hungry bird was diverted by a large snake which was devouring a freshly-killed wildebeest. The end result of this tragic encounter was the snake's new-found and everlasting ability to shed its skin, one less bird and wildebeest, and the continuation of our relentless aging.
Ever since that shattering non-event, we humans have been searching for such a golden talisman – the way toward living forever, well, at least for a lot longer. And doing it in great health. This tantalizing quest has found its way into our fantasy world (Ponce De Leon's Fountain of Youth, Shangri-La, and even such wild ones as Dracula and Frankenstein, etc.). Physicians themselves have, over the years instituted the insertion of such purported life stretchers as goat glands, monkey glands, fetal lamb parts, and more. But as yet, no luck.
We are aware that each living species, plant and animal, has a life span – a time to live and a time to die. We also know the species variability of this span, and that it may be ended prematurely by hostile events. Thus a western fir may live 500 years if someone doesn't chop it down prematurely. A young salmon may swim downstream out to sea, mature a few years, and if not caught by one of us or by a bear as it fights its way back upstream, will there spawn and die. Our human life span, when not thwarted and foreshortened by disease, pestilence, famine, wars, personal sloth, and so on, is about 80 (fourscore) years.
All of these life spans are controlled by that living organism's genetic makeup. Our genes control all the events that go on within us as we live, grow, reproduce and age, and they can sometimes mutate and change on their own, or by our behavior, or by our environment, but finally though, will age us to death. Laboratory studies of animal aging have recently revealed considerable valuable evidence about the events that promote, as well as those that delay aging. Such works have markedly narrowed our search for the mechanisms to delay our aging and the degenerative diseases that accompany it. One very significant laboratory finding was the effect of diet upon animal aging. A small nutritious diet could double the life expectancy of these animals whilst a heavier yet similar diet did their compatriots in.
Research involving humans is beginning to reveal the same age-delaying benefits of modest, low-calorie and nutritious diets. Although there are many sources of such evidence, one that caught all of our eyes was the "biosphere" experiment. You may recall that little self-contained world which was built in the Arizona desert and, totally sealed away, could provide food, oxygen, waste management, everything necessary to sustain and promote life (even a few insects were allowed in!) without any outside support or intervention. In one experiment four men and four women researchers established a life within this biosphere, and remained there for two years. They were sustained, among other things, with a low 1,800 calorie diet that, although not fulfilling, was completely nutritious. None were overweight to begin with, but they all lost weight. Physical and biochemical studies on these eight "survivors" all revealed improved general health, and amid an abundance of excellent lab results (blood cholesterol, for instance, in the 120 mg range) was a marked reduction in fasting insulin levels. We'll see what that may mean.
There is much other more important work being done on aging. Caloric restriction has clearly gained momentum in this field particularly because of its striking life and health prolongation noted in animal research.
It is widely held by aging investigators that our bodies' production and expenditure of energy, either at rest (our basic metabolic rate – BMR) or during activity, also produces destructive oxidative particles called reactive oxygen species, sort of like ashes from a wood fire. Over years, these destructive particles accumulate and lead eventually and gradually to aging, its diseases, and to death. The free oxygen radicals that we hear about so much today are a part of this phenomenon.
In order to study further the effect of caloric restriction on humans, such a restrictive dietary program, code named CALERIE, was undertaken in this country and was recently reported in the Journal of the American Medical Association. At the end of six months, the study volunteers were found to have bettered two important biomarkers of longevity – their body temperature (therefore their BMR) had decreased, and their fasting insulin levels were significantly reduced. Thus, in both cases, fewer ashes.
It would be almost impossible for us to summon the will to follow such a stringent, though nutritious, 1,800-calorie daily diet while surrounded by the constant temptation of such plenty. There is, however, mounting evidence, as noted here, that a low calorie diet is our ticket to a healthy long life – always provided, of course, that some other devilment doesn't waylay us. As with all else American, if more than two people are interested in anything, a club or society gets going. Learn more about this low calorie subject, therefore, from the Calorie Restriction Society at www.calorierestriction.org.
Incidentally, one of the eight biosphere participants was Professor Roy Walford, M.D., a pathologist, who did major work on aging and the delaying effects of a low calorie diet long before his stint in the dome. He planned to live to be 120 and he might have achieved that goal, had he not been struck down in his 70s by amyotrophic lateral sclerosis – the so-called Lou Gehrig disease – his personal devilment. Our own best chance for a longer healthier life clearly lies in our diet, our habits, and our activity. Our hope for everlasting life lies only in our Bible.
Senior Health By Clark Gillespie
According to an African legend, God sent a scavenging bird called a Halawaka out into the world with instructions for our endless self-renewal. The instructions were simple – as age crept upon us, we simple shed our skin and emerged refreshed and new. On its journey, however, the unreliant and hungry bird was diverted by a large snake which was devouring a freshly-killed wildebeest. The end result of this tragic encounter was the snake's new-found and everlasting ability to shed its skin, one less bird and wildebeest, and the continuation of our relentless aging.
Ever since that shattering non-event, we humans have been searching for such a golden talisman – the way toward living forever, well, at least for a lot longer. And doing it in great health. This tantalizing quest has found its way into our fantasy world (Ponce De Leon's Fountain of Youth, Shangri-La, and even such wild ones as Dracula and Frankenstein, etc.). Physicians themselves have, over the years instituted the insertion of such purported life stretchers as goat glands, monkey glands, fetal lamb parts, and more. But as yet, no luck.
We are aware that each living species, plant and animal, has a life span – a time to live and a time to die. We also know the species variability of this span, and that it may be ended prematurely by hostile events. Thus a western fir may live 500 years if someone doesn't chop it down prematurely. A young salmon may swim downstream out to sea, mature a few years, and if not caught by one of us or by a bear as it fights its way back upstream, will there spawn and die. Our human life span, when not thwarted and foreshortened by disease, pestilence, famine, wars, personal sloth, and so on, is about 80 (fourscore) years.
All of these life spans are controlled by that living organism's genetic makeup. Our genes control all the events that go on within us as we live, grow, reproduce and age, and they can sometimes mutate and change on their own, or by our behavior, or by our environment, but finally though, will age us to death. Laboratory studies of animal aging have recently revealed considerable valuable evidence about the events that promote, as well as those that delay aging. Such works have markedly narrowed our search for the mechanisms to delay our aging and the degenerative diseases that accompany it. One very significant laboratory finding was the effect of diet upon animal aging. A small nutritious diet could double the life expectancy of these animals whilst a heavier yet similar diet did their compatriots in.
Research involving humans is beginning to reveal the same age-delaying benefits of modest, low-calorie and nutritious diets. Although there are many sources of such evidence, one that caught all of our eyes was the "biosphere" experiment. You may recall that little self-contained world which was built in the Arizona desert and, totally sealed away, could provide food, oxygen, waste management, everything necessary to sustain and promote life (even a few insects were allowed in!) without any outside support or intervention. In one experiment four men and four women researchers established a life within this biosphere, and remained there for two years. They were sustained, among other things, with a low 1,800 calorie diet that, although not fulfilling, was completely nutritious. None were overweight to begin with, but they all lost weight. Physical and biochemical studies on these eight "survivors" all revealed improved general health, and amid an abundance of excellent lab results (blood cholesterol, for instance, in the 120 mg range) was a marked reduction in fasting insulin levels. We'll see what that may mean.
There is much other more important work being done on aging. Caloric restriction has clearly gained momentum in this field particularly because of its striking life and health prolongation noted in animal research.
It is widely held by aging investigators that our bodies' production and expenditure of energy, either at rest (our basic metabolic rate – BMR) or during activity, also produces destructive oxidative particles called reactive oxygen species, sort of like ashes from a wood fire. Over years, these destructive particles accumulate and lead eventually and gradually to aging, its diseases, and to death. The free oxygen radicals that we hear about so much today are a part of this phenomenon.
In order to study further the effect of caloric restriction on humans, such a restrictive dietary program, code named CALERIE, was undertaken in this country and was recently reported in the Journal of the American Medical Association. At the end of six months, the study volunteers were found to have bettered two important biomarkers of longevity – their body temperature (therefore their BMR) had decreased, and their fasting insulin levels were significantly reduced. Thus, in both cases, fewer ashes.
It would be almost impossible for us to summon the will to follow such a stringent, though nutritious, 1,800-calorie daily diet while surrounded by the constant temptation of such plenty. There is, however, mounting evidence, as noted here, that a low calorie diet is our ticket to a healthy long life – always provided, of course, that some other devilment doesn't waylay us. As with all else American, if more than two people are interested in anything, a club or society gets going. Learn more about this low calorie subject, therefore, from the Calorie Restriction Society at www.calorierestriction.org.
Incidentally, one of the eight biosphere participants was Professor Roy Walford, M.D., a pathologist, who did major work on aging and the delaying effects of a low calorie diet long before his stint in the dome. He planned to live to be 120 and he might have achieved that goal, had he not been struck down in his 70s by amyotrophic lateral sclerosis – the so-called Lou Gehrig disease – his personal devilment. Our own best chance for a longer healthier life clearly lies in our diet, our habits, and our activity. Our hope for everlasting life lies only in our Bible.
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