Searching for the elixir of life? The secrets to better health?
Okay, to start off, let’s point out the obvious. Every species on earth has an essential maximum lifespan, from 24 hours for say a species of fly, to a Bowhead whale which lives up to 211 years. For humans it’s about 111 years.
The question is:
What can we do to maximize our lifespan?
The answer is:
Caloric restriction!
We have spoken about caloric restriction (CR) and its potential benefits before. It has now been studied for almost 100 years and evidence proves that as long as one's diet contains a broad range of critical nutrients, reducing the daily caloric intake does indeed have significant rewards, including slowing the aging process, improving overall health, and potentially increasing longevity.
So let's consider calorie restriction as not just a gerontological tool but also as a health tool, and, most importantly, not as a diet but as a lifestyle. The question of longevity is about not just extending the maximum age of humans, but also maximizing health for the entire length of that life. Despite the complex scientific debate, the idea is simple: CR is not about extending life by some marked amount, but about your ideal health right up to the time of death (which may be extended somewhat, but even so, that is not the point.)
The effects of CR have been observed in a variety of species including yeast, mice, worms and fish, and there's plenty of evidence that calorie restriction has a similar effect on the human lifespan as well.
One of the earliest and most recognized studies of caloric restriction was done on a species of mice. The control group was kept on a normal diet and the test group was put on a diet restricted in calories but still nutritionally sufficient (called calorie restriction with adequate nutrition or CRAN). The results were amazing as the life span of the control group was 41 months, which is about 110 human years, but the test group of calorie-restricted mice lived to 56 months, or 150 human years! Science has proven that restricting daily caloric intake slows down the metabolism and forces the cells regererate more efficiently.
Many more studies have followed over the last half century, including over 500 peer reviewed articles, and there is a consistent result throughout: calorie restricted diets increase the maximum life span of every tested species, as well as increasing the average life span. Study after study, the pay off of CR is both longer and healthier life. Lower caloric intake equals lower disease rates and more robust health.
Are there any consensus theories behind the benefits of caloric restriction?
Scientists are still assessing the mechanism based on a range of possibilities, so the jury is still out. What we do know is that CR certainly increases DNA cellular repair, increases the heat shock protein response, definitely decreases oxidative damage, decreases glycation, delays age-related immunological decline, and probably (there is some debate here) increases the body's own antioxidant defense systems.
Results from a human study conducted inside Biosphere 2 showed that CR specifically lowered cholesterol by up to 35 percent, blood sugar and insulin by up to 20 percent, blood pressure by more than 20 percent, and induced other changes also seen in CR animals.
One important study on a vinegar worm showed that when a particular gene called daf-2 was manipulated, the worm's life span was increased by up to 300 percent, and has offered some strong clues as to how to interpret human results. Harvard Medical School scientists explain that the daf-2 gene is fundamental to the insulin-glucose metabolic pathway of all subjects, humans included (we all share this gene). Furthermore, insulin and glucose levels are substantially reduced in calorie restricted subjects of all species. So effects on the worm, which are equivalent to improvements induced by CR in mammals, suggests a general link between metabolism, hibernation mechanisms, and longevity.
So there are currently two prevailing theories about what makes CR effective. One is based on "metabolic efficiency," or efficiency in the body's generation of energy and the way it utilizes glucose. The other is based on the acquired evolutionary response in animals when they face recurring periods of food shortage and their bodies adapt to re-allocate energy from growth and reproduction to just maintenance and survival. Hibernation is a form of this adaptation. Analysis of the biochemistry of hibernation reveals similar activity in the body to CR's effects, including a small but significant drop in body temperature in diet-restricted subjects.
Finding the definitive answer about where CR benefits derive from is still problematic due to the number of processes involved, but at least we know what to look for and where to look. Studies are currently being done on primates (University of Wisconsin) but we won't see results for some time. But the science is almost certainly clear. CR does have life extension and health benefits.
Scientists have determined that fasting triggers cellular responses that boost stress resistance and reduce oxidative damage and inflammation. In rodents, fasting protects against diabetes, cancer, heart disease and neurodegeneration. So far, every species tested shows the same basic results. In particular, the physiological results from rodent CR are the same in primates. While we may have to wait for a few years before the jury comes back with a categorical answer, we can confidently say that CR does increase lifespan and health indicators in humans.
We can also look at societies around the world where food intake is reduced (not starving -- complete nutrition but lower intake) for further evidence. For instance, Japan has some of the most long-lived people on the planet, and they have a lower calorie intake as well. In fact most cultures with lower caloric consumption (assuming a healthy diet nonetheless) do live slightly longer and with less disease and better health.
In addition, we can look at type II diabetics who clearly and quickly improve all health indicators with caloric reduction. Studies have also led researchers to hypothesize that reducing caloric intake could potentially help inhibit the overexpression of the protein Mcl-1, which is associated with several cancers. The list of benefits continues to grow.
As we said above, CR is not a diet but a lifestyle. It is not about counting calories, or eating like an ascetic monk, but is about making every calorie count. As you reduce intake you must increase quality. You must be even more careful about your diet, making sure to get a good balance from proteins, vegetables, fruits, seeds, grains, fats, and nuts. You still need a full daily dose of required vitamins, minerals, and amino acids. CR meals need to be broad. Again the Japanese are a good example here. They have very complex nutritious meals but simply smaller.
Studies show that daily caloric reductions of between 10-30% are ideal and benefits are still clear even at 10%. Anything below 50% reduction and you are heading for trouble. Furthermore, benefits do not take years -- they show almost immediately -- and are just as evident in older animals who have never used CR before.
The main problem with CR is simply that it is very hard for people to stay on it.
Good News !
Intermittent Fasting May Work Even Better Than Calorie Restriction.
Studies using alternate-day fasting have shown that it has similar effects to CR and in some cases even better results. This is an option we can realistically embrace. There are different variations of intermittent fasting and they all show significant rewards. The most common is the 4 day eating, then 1 day fasting approach. If a full 24 hours of fasting is untenable, then keeping an 8 hour food-free window in your day can substitute.
First, we should talk about the metabolic process. Most people require 8 to 12 hours to burn the sugar stored as glycogen, but because most people eat three meals a day, they never actually burn their glycogen stores. Consequently, the body learns to burn sugar as a primary fuel and stops using fat as a primary fuel (which is what we want.)
So the basic law is that you must fast for at very least 8-12 hours to get you into the correct weight loss mode. If a full day of not eating is just too extreme, you could simply restrict your eating to between noon and 8pm. Do not eat anything for three hours before bed, or for 4 hours after rising. This is a daily fast of 16 or so hours, and is plenty to deplete your glycogen stores and get you switched into fat-burning mode.
A few things to remember.
While most people will switch over to burning fat after several weeks of intermittent fasting, it could take several months to teach your body to switch on the fat-burning enzymes that allow your body to use fat as its primary fuel. So first rule is to persist. Don't give up!
If you are pregnant (or breastfeeding), hypoglycemic, have any adrenal issues or cortisol regulation issues, are type 1 diabetic, or still growing you should avoid any type of fasting. Even if you are healthy, check with your doctor before getting started.
Proper supplementation is more important on CR diets. I found that in the beginning of my own program, a well-balanced appetite suppressant really helps on occasion.
The other good news is that there are certain supplements are CR mimetic -- proven to imitate CR in the way it affects cell regeneration but without affecting metabolism. Resveratrol is the most widely known of the CR mimetics and can offer many valuable health benefits.
It is also critical to do muscle building exercises, as there is a risk of muscle deterioration or reduced muscle strength on CR. While we are on the subject, the benefits of exercise are shown to be even greater while on CR.
I firmly believe in the positive effects of CR. A BBC documentary called "Eat, Fast and Live Longer" was made by Dr Michael Mosley in which he analyzes the results of his own tests with various fasting regimes. I highly recommend it for anyone who is still uncertain about the rewards of caloric restriction.
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References:
Approaches for quantifying energy intake and % calorie restriction during calorie restriction interventions in humans: the multicenter CALERIE study. Racette SB1, Das SK, Bhapkar M, Hadley EC, Roberts SB, Ravussin E, Pieper C, DeLany JP, Kraus WE, Rochon J, Redman LM; CALERIE Study Group. Am J Physiol Endocrinol Metab. 2012 Feb 15; Epub 2011 Nov 29.
Caloric restriction reduces age-related and all-cause mortality in rhesus monkeys. Ricki J. Colman,T. Mark Beasley,Joseph W. Kemnitz, Sterling C. Johnson,Richard Weindruch and Rozalyn M. Anderson; Nature, Oct 2013.
Weindruch, R. H. and Walford, R. L.The Retardation of Ageing and Disease by Dietary Restriction, Charles C Thomas (1988).
Ramsey, J. J., Laatsch, J. L. and Kemnitz, J. W.Age and gender differences in body composition, energy expenditure, and glucoregulation of adult rhesus monkeys. J. Med. Primatol.29, 11–19(2000).
ILAR Committee on Animal Models for Research on Ageing. Mammalian Models for Research on Ageing; National Academy (1981).
Fontana, L., Partridge, L. and Longo, V. D.Extending healthy life span--from yeast to humans. Science.
The opinions expressed in this article are of the author. Content and other information presented on the site are not meant to be medical advice or any substitute for professional advice, counseling, diagnosis, or treatment. Never delay or disregard professional medical or mental health advice from your physician or other qualified health provider.
