Read More: The Calorie Restriction Society
An alternative: Calorie restriction:
Intermittent fasting as an alternative approach- - -
Studies by Mark P. Mattson, Ph. D., chief of the National Institute on Aging's (NIA) Laboratory of Neurosciences, and colleagues have found that intermittent fasting and calorie restriction affect the progression of diseases similar to Huntington's disease, Parkinson's disease, and Alzheimer's disease in mice (PMID 11119686). In one study, rats and mice ate a low-calorie diet or were deprived of food for 24 hours every other day (PMID 12724520). Both methods improved glucose metabolism, increased insulin sensitivity, and increased stress resistance. Researchers have long been aware that calorie restriction extends lifespan, but this study showed that improved glucose metabolism also protects neurons in experimental models of Parkinson's and stroke.
Another NIA study found that intermittent fasting and calorie restriction delays the onset of Huntington's disease-like symptoms in mice and prolongs their lives (PMID 12589027). Huntington's disease (HD), a genetic disorder, results from neuronal degeneration in the striatum. This neurodegeneration results in difficulties with movements that include walking, speaking, eating, and swallowing. People with Huntington's also exhibit an abnormal, diabetes-like metabolism that causes them to lose weight progressively.
This NIA study compared adult HD mice who ate as much as they wanted to HD mice who were kept on an intermittent fasting diet during adulthood. HD mice possess the abnormal human gene huntingtin and exhibit clinical signs of the disease, including abnormal metabolism and neurodegeneration in the striatum. The mice on the fasting program developed clinical signs of the disease about 12 days later and lived 10 to 15% longer than the free-fed mice. The brains of the fasting mice also showed less degeneration. Those on the fasting program also regulated their glucose levels better and did not lose weight as quickly as the other mice. Researchers found that fasting mice had higher brain-derived neurotrophic factor (BDNF) levels. BDNF protects neurons and stimulates their growth. Fasting mice also had high levels of heat-shock protein-70 (Hsp70, which increases cellular resistance to stress.
Another NIA study indicates that intermittent fasting may be more beneficial than cutting calorie intake. Researchers let a control group of mice eat freely. Another group was fed 60% of the calories that the control group consumed. A third group was fasted for 24 hours, then permitted to free-feed.  According to an Associated Press article (29 April 2003), the fasting mice "didn't cut total calories because they ate twice as much on days they weren't fasting. Both the fasting mice and those on a restricted diet had significantly lower blood sugar and insulin levels than the free-fed controls. A toxin that damages hippocampal cells was injected in all of the mice. Hippocampal damage is associated with Alzheimer's. Interestingly, the scientists found less damage in the brains of the fasting mice than in those that ate either a restricted or a normal diet. The NIA is planning a human study that will compare a group eating three meals a day with a group eating the same diet and amount of food within four hours and then fasting 20 hours."
In a television interview with Meredith MacRae c. 1984, Roy Walford mentions intermittent fasting and its dramatic effects on animal life span through "undernutrition without malnutrition".
Gene clue to longevity uncovered
By Rebecca Morelle Science reporter, BBC News
The mystery of how eating less boosts longevity is closer to being solved.
Studies have shown that severe calorie restriction markedly extends lifespan in mice and many other species - but the reasons for this remained elusive.
But now US research on nematode worms, published in Nature, has uncovered a gene linked to this unusual effect.
In the future, the find could lead to drugs that mimic the consequences of calorie restriction but negate the need for severe fasting regimes.
The life-lengthening properties of reducing calorie intake were first discovered in the 1930s, when laboratory rodents fed a severely reduced diet were found to outlive their well-fed peers.
Since then, this effect has been observed on organisms as diverse as yeast, flies, worms and dogs.
The consequences for humans of cutting calorie intake by about 60% while maintaining levels of vital nutrients are still unclear, although this extreme diet has a number of followers.
Andrew Dillin, an author of the paper and an associate professor at the Salk Institute for Biological Studies, said: "If you reduce food too much, you go towards starvation and live less long. If you overeat you will succumb to obesity and have a short lifespan. Dietary restriction is really a sweet-spot between the two.
"But for 72 years, we have not known how it works."
A study using nematode worms (Caenorhabditis elegans) revealed that a gene called pha-4 played a key role.
The team found worms that had their pha-4 genes removed showed no enhanced longevity while on the restricted diet.
But they discovered that the opposite experiment - over-expressing levels of pha-4 in the worms - increased longevity when on the restricted diet.
"This is the first gene we have found that is absolutely essential to the longevity response to dietary restriction," explained Dr Dillin.
"We finally have genetic evidence to unravel the underlying molecular programme required for increased longevity in response to calorie restriction."
Feast or famine
Although the study was carried out on worms, the finding could also be important for other species.
Mammals, including humans, possessed genes that were highly similar to the pha-4 gene, explained Dr Dillin.
These genes play a key role in development, and then in later life in the regulation of glucagon, a hormone that has a major role in maintaining glucose levels in blood - especially during fasting.
In fact, scientists believe the life-increasing effect of dietary restriction may be linked to boosting chances of survival through times of food scarcity.
"Pha-4 may be the primordial gene to help an animal overcome stressful conditions to live a long time through dietary restriction conditions," explained Dr Dillin.
Scientists now plan to look at the gene in other species.
Should the longevity link also apply to humans, it could open the door to the development of drugs that mimic the effects of calorie restriction while allowing people to maintain their normal diet, the scientists said.
Professor Richard Miller of the Institute of Gerontology at the University of Michigan, commented: "It is really hard to guess whether the connections that we see between the pha-4 system and calorie restriction in worms will have parallels in mammals, whose repertoire of responses to various forms of long- and short-term food shortages are far more complex than those of worms.
"But the Dillin paper provides both motivation to look and also clues about where to look. I think it's likely to be influential, even if the implications for mammals do eventually turn out to be a cul-de-sac - which they might or might not."
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/6612411.stm
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Extreme dieting: Eat less, live longer?
By Rebecca Morelle Science reporter, BBC News
Scientists believe they are a step closer to working out why an extremely restrictive diet boosts longevity.
This well-documented calorie-cutting phenomenon has been seen in many species, from yeast to mice to dogs.
Although the effects of "calorie restriction" in humans are as yet unknown, some are undertaking this in a bid to live longer.
Here, Bob Cavanaugh, managing director of the Calorie Restriction Society, tells the BBC News website about his diet.
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/6617113.stm
I've been doing calorie restriction for six years.
When I was 53, I had a physical and found out my blood cholesterol level was very high. My doctor wanted to try to control it with diet before resorting to drugs, and I was all in favour of that.
I had read a book about calorie restriction and ageing back in 1988, and was convinced by the science, so I decided to try it.
I use software to work out what to eat everyday. I believe without it, it is impossible to have proper nutrition.
You weigh your food, and it works out the calories, the ratio of fat, carbohydrate and protein and the breakdown of vitamins, minerals and amino acids, then runs a nutritional profile of what you eat throughout the day.
On an average day, I eat 1,800 calories. Younger people can restrict their calories more severely, but I've been told that, based on lab animal evidence, I have already accumulated years of damage to my mitochondria (the powerhouses of the cells), so I utilise my food less efficiently than a younger person.
On a typical day, I will eat an oatmeal-based recipe for breakfast, which is about 455 calories and it gives me about half of my daily nutrients.
I don't eat lunch - after this breakfast I just don't feel hungry - so that leaves me about 1,350 calories for my evening meal, which is a lot.
If you are smart, by eating small portions of meat and small quantities of starchy things, that leaves an enormous amount of room for fruit and vegetables. You wind up eating quite a large meal and it is very filling, nutritious and satisfying.
Contrary to popular belief, you are not hungry on this diet, and I feel excellent. When I started the diet when I was 53, I felt like I was starting to get on in years and didn't quite have the vim and vigour I used to have.
But starting calorie restriction, that exhilaration that I used to experience in youth returned and my whole sense of well-being returned to levels I experienced as a child.
It really made me feel like I got my life back.
In terms of health, my cholesterol level has really dropped; I now weigh 150lb, and I haven't had any illnesses at all - not even a cold.
My motivation for doing calorie restriction was two-fold. One was to reduce my risk of age-related diseases such as heart disease - with the cholesterol level I had. I was in line for this.
And the prospect of extending your lifespan is very appealing - although I guess you have to be somewhat narcissistic to think you are worth living a lot longer than anyone else.
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Worm gene linked to longevity
LAJOLLA, Calif., May 2, 2007 (UPI) -- California researchers say they have located a gene that helps low-calorie diets increase longevity in animals.
The scientists say the discovery of the gene PHA-4 in worms may lead to new understanding of the "starvation response" in animals. The researchers said that could then lead to new drugs that delay the onset of age-related diseases in humans, The Wall Street Journal reported Thursday.
The report was published online in the journal Nature.
Senior scientist Andrew Dillin of the Salk Institute for Biological Studies in La Jolla, Calif., said PHA-4 coordinates other genes that influence how the adult worm's body responds to a restricted diet. He said humans possess three genes that are very similar to PHA-4.
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Calorie reduction may lead to longer life
LONDON, April 19, 2007 (UPI) -- An Imperial College London canine study suggests a calorie-restricted diet might result in extended longevity.
In the study led by Jeremy Nicholson, Labrador retriever dogs fed a calorie-restricted diet showed different lifelong patterns relating to energy metabolism and the activities of their gut microbes. The dogs lived nearly two years longer than similar dogs given a slightly higher-calorie diet.
Nicholson and colleagues from Nestle Purina Research centers in Switzerland and the United States noted previous studies also established calorie restriction as a proven method for extending the lifespan of animals. But that research did not explain how calorie restriction works.
The new study suggests some beneficial changes might relate to the activities of symbiotic bacteria that live in the intestinal tract. Those microbes, the scientists said, produce a range of biochemicals that might influence disease processes and alter energy metabolism in host organisms.
Researchers said although their goal was to help develop diets that keep pets alive and healthy for as long as possible, the findings might also be relevant to human dietary changes and obesity.
The study is scheduled for the May 4 issue of the Journal of Proteome Research.