In E. B White's beloved novel Charlotte's Web, an old sheep advises the gluttonous rat Templeton that he would live longer if he ate less. “Who wants to live forever?” Templeton sneers. “I get untold satisfaction from the pleasures of the feast.”

It is easy to empathize with Templeton, but the sheep's claim has some merit. Studies have shown that reducing typical calorie consumption, usually by 30 to 40 percent, extends life span by a third or more in many animals, including nematodes, fruit flies and rodents. When it comes to calorie restriction in primates and people, however, the jury is still out. Although some studies have suggested that monkeys that eat less live longer, a new 25-year-long primate study concluded that calorie restriction does not extend average life span in rhesus monkeys. Even if calorie restriction does not help anyone live longer, a large portion of the data supports the idea that limiting food intake reduces the risks of diseases common in old age and lengthens the period of life spent in good health.

If only one could claim those benefits without being hungry all the time. There might be a way. In recent years researchers have focused on a strategy known as intermittent fasting as a promising alternative to continuous calorie restriction.

Intermittent fasting, which includes everything from periodic multiday fasts to skipping a meal or two on certain days of the week, may promote some of the same health benefits that uninterrupted calorie restriction promises. The idea of intermittent fasting is more palatable to most people because, as Templeton would be happy to hear, one does not have to renounce the pleasures of the feast. Studies indicate that rodents that feast one day and fast the next often consume fewer calories overall than they would normally and live just as long as rats eating calorie-restricted meals every single day.

In a 2003 mouse study overseen by Mark Mattson, head of the National Institute on Aging's neuroscience laboratory, mice that fasted regularly were healthier by some measures than mice subjected to continuous calorie restriction; they had lower levels of insulin and glucose in their blood, for example, which signified increased sensitivity to insulin and a reduced risk of diabetes.

The First Fasts

Religions have long maintained that fasting is good for the soul, but its bodily benefits were not widely recognized until the early 1900s, when doctors began recommending it to treat various disorders—such as diabetes, obesity and epilepsy.

Related research on calorie restriction took off in the 1930s, after Cornell University nutritionist Clive McCay discovered that rats subjected to stringent daily dieting from an early age lived longer and were less likely to develop cancer and other diseases as they aged, compared with animals that ate at will. Research on calorie restriction and periodic fasting intersected in 1945, when University of Chicago scientists reported that alternate-day feeding extended the life span of rats as much as daily dieting in McCay's earlier experiments. Moreover, intermittent fasting “seems to delay the development of the disorders that lead to death,” the Chicago researchers wrote.

In the next decades research into antiaging diets took a backseat to more influential medical advances, such as the continued development of antibiotics and coronary artery bypass surgery. More recently, however, Mattson and other researchers have championed the idea that intermittent fasting probably lowers the risks of degenerative brain diseases in later life. Mattson and his colleagues have shown that periodic fasting protects neurons against various kinds of damaging stress, at least in rodents. One of his earliest studies revealed that alternate-day feeding made the rats' brains resistant to toxins that induce cellular damage akin to the kind cells endure as they age. In follow-up rodent studies, his group found that intermittent fasting protects against stroke damage, suppresses motor deficits in a mouse model of Parkinson's disease and slows cognitive decline in mice genetically engineered to mimic the symptoms of Alzheimer's. A decidedly slender man, Mattson has long skipped breakfast and lunch except on weekends. “It makes me more productive,” he says. The 55-year-old researcher, who has a Ph.D. in biology but not a medical degree, has written or co-authored more than 700 articles.

7 Comments

1. 1. jessamyn 09:32 AM 1/11/13

   There's a big piece missing here, which is that intermittent fasting has fewer positive benefits and many more negative benefits for women. A lot more research on women specifically is needed, but it seems from what's out there that the hormonal response is quite different between the sexes. A good review of the existing studies and their implications for women can be found here:
   
   http://www.paleoforwomen.com/shattering-the-myth-of-fasting-for-women-a-review-of-female-specific-responses-to-fasting-in-the-literature/

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2. 2. jackvandijk 03:48 PM 1/11/13

   I get so hungry when I fast, but yes, I may eat less, or more simple like a piece of bread.

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3. 3. The Ethical Skeptic 11:07 PM 1/13/13

   Great article, and this wisdom has been bolstered by circumstantial statistics for decades. What has not been tested under the scientific method is the underlying set of contributors, which result in this set of observation statistics, the correlation between lower caloric consumption and longer life, occurring. The hypothesis is not "My set of statistics observed = valid," rather the Hypothesis is "Factor Y results in a statistically significant covariant contribution in domain A and B simultaneously in one sub-species in the same environment and familial genome"
   
   As we now see that a very significant portion of the day's caloric burn is enacted by the brain and not the body, would we now consider that thinkers die earlier? I am not sure that the evidence would support this contention. As we find that some excessive caloric intakes are associated causally with specific illnesses, illnesses pandemic in the United States (for instance the gram negative toxic impact of h. pylori on the human blood sugar serum, or diabetes and heart disease links), we must weave into the continued falsification hierarchy the hypothesis that excessive caloric consumption is an outcome profile and not an input factor; a symptom of an underlying cause, which is peer to, and not prerequisite to a shortened lifespan. This science has yet to be done. But in the meantime, yes - I plan to lower my caloric intake accordingly. Great stuff! - TES

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4. 4. Crasher 07:14 PM 1/15/13

   I think that periodic fasting would closely resemble the way humans have eaten for thousands of years. It make sense then for evolution to have 'selected' for genes that make this a 'healthy' way to live. I also think that period stressing of our systems is good for us. Like exercise is a method of stress that build fitness. Perhaps going hungry is a good stressor that strenghens other systems.

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5. 5. shroomer_dave in reply to jessamyn 02:16 AM 1/16/13

   In a more natural life sytle Fasting is Essential for physical ,mental and spiritual health . The "hormonal response" at present(normal)is in Horrible Disarray . Commercial Production of meat, dairy and poultry along with 'genetically modified' vegetables and grains has inundated ,most of what we eat ,with artificial hormones,antibiotics and multiple toxins from pesticides and petroleum based fertilizers.Add to that Further Processing, preserving, stabilizing, sweetening, coloring, flavor enhancing,...Well,that's the point .All of History in Every Culture has Fasting rituals or customs . In winter time the PLANET Fasts .A time to rest purely 'in tune' with nature! Remove the unnecessary debris from your Heart and Arteries , bloodstream,lungs,muscles,and intestines - herbal teas might be added.Fasting removes the Impurities in our Souls .Doing without,at the Time the Earth Offers the Least.Personal Sacrifice,Facing temptation ,Strengthening your own personal resolve and sharing with friends and family . Systematic under eating and periodic fasting are good for the person and the Planet.

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6. 6. terryb15d 03:32 PM 1/20/13

   Free Radic Biol Med. 2011 Oct 1;51(7):1454-60.
   
   Long-term intermittent feeding, but not caloric restriction, leads to redox imbalance, insulin receptor nitration, and glucose intolerance.
   
   Calorie restriction is a dietary intervention known to improve redox state, glucose tolerance, and animal life span. Other interventions have been adopted as study models for caloric restriction, including nonsupplemented food restriction and intermittent, every-other-day feedings. We compared the short- and long-term effects of these interventions to ad libitum protocols and found that, although all restricted diets decrease body weight, intermittent feeding did not decrease intra-abdominal adiposity. Short-term calorie restriction and intermittent feeding presented similar results relative to glucose tolerance. Surprisingly, long-term intermittent feeding promoted glucose intolerance, without a loss in insulin receptor phosphorylation. Intermittent feeding substantially increased insulin receptor nitration in both intra-abdominal adipose tissue and muscle, a modification associated with receptor inactivation. All restricted diets enhanced nitric oxide synthase levels in the insulin-responsive adipose tissue and skeletal muscle. However, whereas calorie restriction improved tissue redox state, food restriction and intermittent feedings did not. In fact, long-term intermittent feeding resulted in largely enhanced tissue release of oxidants. Overall, our results show that restricted diets are significantly different in their effects on glucose tolerance and redox state when adopted long-term. Furthermore, we show that intermittent feeding can lead to oxidative insulin receptor inactivation and glucose intolerance.
   PMID: 21816219
   
   Intermident fasting seems like a pretty bad idea in light of this study.
   

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7. 7. bucketofsquid 04:04 PM 1/30/13

   The only impartial study I've seen involving food intake and lifespan was the comparison of lifespans of Swedes born in famine or plenty years. Those born in years with abundant harvests died significantly younger than those born in famine years.
   
   We have known for centuries that the wealthy tend to have much worse diets and lifestyles. It is called "succeeding to death".

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