The crux of intermittent fasting

It is less than futile, in fact, it is outright nonsensical, to argue in favour of or promote an explanation that is in contradiction with observational evidence. What is required is to find, or at least try to find, a sound and well-founded explanation. And not just for some of the observations, but for each individual observation, as well as for the entire ensemble of observations. This is what we should do.

Fasting means not eating; everyone knows that. The meaning of the word has been loosened to include not consuming appreciable amounts of calories, as in doing a green juice fast, for example, but which should instead rightly be called a cleanse. The expression intermittent fasting implies a cycle of some kind, and is used to mean not eating for periods of 16, 18, 24 or 48 hours, but on a regular basis, like every week or even every day.

Fasting has been known and recognised for its often quasi-miraculous curative effects for thousands of years. Indeed, it is possible to find accounts of individuals recovering from just about any ailment and disease imaginable simply from fasting long enough. It seems, however, that fasting as a healing modality, has, over the past couple of centuries, steadily grown less popular in the medical profession and, as a consequence, also in the general population.

A resurgence of scientific interest over the last decades in the benefits of fasting for treating various degenerative conditions like arthritis and cancer, but also for extending healthy lifespan about which I will write at one point in the future, has brought it back into the spotlight, especially in circles of optimal health enthusiasts, which includes some gym go-ers and body builders interested not so much in optimal health, but mostly in losing fat and gaining muscle.

Therefore, there has been quite a few people trying out or adopting intermittent fasting for periods of a few weeks to a few months, or even longer, but reading things here and there shows that they have had varying success given their initial motivations, whatever those might have been.

Ori Hofmekler was one of the first to popularise the idea of intermittent fasting with his book The Warrior Diet. He has continued to write and to encourage intermittent fasting for a wide range of benefits, especially in regards to the goal of improving body composition, as one of his last titles expresses perfectly: Maximum Muscle, Minimum Fat.

Dr Hertoghe, the world famous endocrinologist and anti-ageing specialist, as well as Mark Sisson (Primal Blueprint) have also been vocal and influential proponents of intermittent fasting for a while. More recently, Dr Mercola did several interviews with Hofmekler, and wrote a few articles on the topic, sharing his experience and enthusiasm for the health and fitness benefits intermittent fasting can bring. These are just some of the well known players that I know of and respect in the natural health community, that have endorsed and promoted this kind of cyclical fasting.

Naturally, as is the case for almost any topic we can think of, there are opposing opinions and, in fact, bashing of intermittent fasting as a means to improve health and body composition, especially in the popular fitness and gym culture. And, as is also the case for almost any topic we can think of, contradictory views and opinions are usually caused by misunderstanding, or at least, incomplete understanding of the elements involved, and in particular the more subtle ones.

On the one hand, we have the proponents claiming that we can very effectively get much healthier, with much improved energy levels, mood, digestion, and natural detoxification and excretion of metabolic acids; normalise and recover the optimal balance of specific hormones, and eventually, of the entire hormonal system; over time lose all excess body fat reserve, increase flexibility and hasten recovery, better preserve our precious muscle tissue and build more very efficiently. And these are just some of the claimed (but also documented) benefits of intermittent fasting.

On the other hand, the nay-sayers and bashers report that these claims are more than just false, they are, in fact, often the exact opposite of what they have found or seen for themselves or in others coming to them for help and expert advice. Reports of feeling really terrible, with massive headaches, bad digestion, awfully low energy levels, and thus, obviously, very bad and destructive moods; loss of some fat but also, over time, of lots or maybe even most of their muscle tissue; extreme hunger, with frightening ravenousness when evening mealtime comes around, leading to monstrous, uncontrolled and uncontrollable overeating without discrimination of food kinds or quality, and over time, showing obvious signs that can be identified as those associated with eating disorders.

How is it possible to have research, studies and documented cases—plenty of documented cases—that provide observational evidence—proof, if you prefer—that support the claims of both of these camps? How can we observe and actually measure such profoundly different consequences in different people that are supposed to follow comparable diets, consequences that are diametrically opposed to one another. In other words, observational evidence that appears to be completely and totally contradictory?

A simple approach, the one espoused by many, maybe most, of the intermittent fasting bashers, is to just say that proponents are wrong and imagining things, letting themselves be fooled by the hype, but actually blind to the reality of the detrimental consequences of practicing cyclical fasting.

For me, the only satisfactory approach is the one that seeks to explain all the observations, to reconcile all the observational evidence, and make sense of the entire ensemble of information available through a physiology and biochemistry based explanation that is complete. I also think it is fair to say that there are more better informed proponents than there are opponents, but this is not obviously the case, and I would thus not bet much on this claim.

Here it is, the crux of the matter, the one single crucial element needed to understand and explain the wide spectrum of apparently contradictory observations that is overlooked because it is misunderstood:

The body’s response to intermittent fasting is entirely dependent upon the state of one’s metabolism, and everything about it hinges on the physiology of nutritional ketosis. 

In fact, the vast majority of the benefits of intermittent fasting are those derived from nutritional ketosis but heightened by the fasted state, and therefore, can only become manifest if the fasting individual is keto-adapted and remains in nutritional ketosis most of the time.

You might be thinking: what in the world is nutritional ketosis, and where’s the explanation for the contradictory observations? Nutritional ketosis is the metabolic state in which the liver manufactures ketone bodies from fat to provide fuel for the brain cells that can only use glucose or ketones for their energy needs. This only happens if and when circulating insulin levels are low, and when blood glucose stays below 80-90 mg/dL for a period of 24-48 hours (generally speaking, on average, and in normal circumstance). The reason is fat will not be burned for fuel is there is plenty of glucose in the blood, and in order to burn fat, insulin must be low.

This metabolic state is induced either by fasting—this is the quickest but also most extreme way to do it, or by eliminating insulin-stimulating carbohydrates (sugars and starches) from the diet—this is by far the easier and obviously much more sustainable way to do it. The longer it is maintained, the better adapted the metabolism becomes. But before ketones are produced to fuel the brain, the body goes through metabolic changes to which it tries to adapt as best it can. The most important but also most severe of them all, is the fundamental shift from using glucose as the primary fuel, not just for the brain, but for all cellular energy needs in the body, to using fats, both from body fat reserves and from food.

The bane of our time is global, chronically elevated insulin levels. Hyper-insulinemia, as it is technically called, sits squarely as one of the root cause of all the diseases of civilisation that kill most (90%) of us today, more or less uniformly across the planet. What does this have to do with our considerations of intermittent fasting? It has everything to do with it:

Insulin is the master hormone that orchestrates the metabolism in what relates to storage and usage of macronutrient (carbs, fats, and proteins) at the cellular level.

Chronically elevated insulin always and inevitably leads to insulin resistance. Insulin resistance means that cells do not respond to insulin as they should, and require ever increasing concentrations of insulin in order to move glucose into the cell. And ever increasing concentrations of insulin means ever increasing inability to use fat cellular fuel, with particular difficulty in unlocking and tapping into the usually greatly overabundant reserves of body fat.

What is truly remarkable is that insulin resistance, even if it has been developing and growing steadily with each passing day and with each high carb meal or snack over our entire lifetime, it can be reversed in weeks when insulin-stimulating carbs are eliminated from the diet: 48 hours to enter nutritional ketosis; one week for water retention release, initial intestinal detox and basic adaptation to fat-burning; four weeks for functional keto-adaptation; and 8 weeks for complete keto-adaptation.

Eliminating insulin-stimulating carbs eliminated the need for large insulin secretions by the pancreas. Therefore, both glucose and insulin concentrations steadily decrease with time, and eventually fat-burning and ketone production kicks in, marking the first step in the transition of the metabolism from sugar-burning to fat-burning, which is what we referred to as fat- or keto-adaptation.

There is a catch though: before fat-burning and ketone production begins, the metabolism of the insulin resistant individual will go through withdrawal from its sugar addiction. First, sugar levels start to drop. After a number of hours, 3 to 4 hours say, blood sugar is too low to supply enough fast-burning glucose to cells for their metabolic activities. Because insulin remains high, and because the body is highly insulin resistant, as we said, it is not possible to use fat from the body’s fat stores. Therefore, it is the liver that comes to the rescue and begins to convert its stores of glycogen into glucose and pumping that into the bloodstream to provide cellular fuel.

Within a few hours, however, the glycogen in the liver is depleted, and blood sugar drops once again, and lower still. Because the body remains unable to tap into its fat reserves due to the state of insulin resistance, it has, at this point, no choice but to turn to muscle tissue, from which it is far easier to breakdown protein and manufacture glucose than it is to start burning fat. And thus, the muscles are eaten away in order to provide the glucose to all of the multitude of insulin resistant (sugar-addicted) cells throughout the organism.

We now come to the final analysis of our observational evidence in regards to intermittent fasting, and consider two scenarios that can explain, as it rightly should, the ensemble of observations in its entirety, and thus clarify and reconcile the apparent contradictions that are seen, and which lead to serious confusion about the issue, even, and maybe especially, among our health, fitness and bodybuilding experts.

Scenario 1: We take a perfectly keto-adapted person who has been eating a diet devoid of insulin-stimulating carbs for a long time, and who therefore always has very low glucose and insulin levels, and as a consequence, exquisite insulin-sensitivity. What happens if they stop eating? Nothing special, really. Their body is always using fat and ketones to supply all healthy body and brain cells with their metabolic energy needs. So, if there is no fat that is provided through the digestive system, then it is taken, without any trouble or noticeable changes in energy levels or concentration, from the body’s fat reserves that are always plentiful, even in the leanest among us with single digit body fat, because 1 gram provides 9 calories, which means that we need only about 200 g for a whole day of normal activities, and have at least 5 kg at any given time (8.5% fat on 60 kg body weight).

Moreover, if we exercise during the fast, there is no noticeable difference because at low intensity, cellular energy needs are taken care of by fat which is continuously released from the fat stores into the bloodstream, while at higher intensity the glycogen stored in the muscle cells themselves, can be used in the form of quick burning glucose together with additional supply from the liver than converts its stores of glycogen if need be (if stress hormones are secreted).

So, biking and working out with weights, for example, is perfectly fine and actually feels great. Even more interesting is the fact that stimulating the muscular system by exercising while fasting triggers the release of various hormones in addition to growth hormone for which there is nothing more effective than fasting, whose purpose is primarily to preserve those physiologically important muscle tissues as essential for functional survival, while breaking down to recycle the proteins of other tissues which are not required like lumps, tumours, and scar tissue. And this means that the hormonal environment created by exercise under fasting conditions is conducive to both preserving and building more muscle, all the while also expediting and maximising fat-burning. And this is what is observed.

Hunger is present at times, but is certainly far from being problematic. There are no headaches, no stomach pains, no sleepiness, no scattered mental discursiveness, no problems concentrating or working. Sitting down to eat the evening’s nutrient-dense, enzyme-rich and high fat meal with adequate amounts of protein for tissue repair and muscle building, is nourishing, perfectly satisfying, and well digested throughout the evening and night, as long as we eat several hours before going to bed. No over-eating, no cravings, no psychological disturbances, no problems at all. A picture of perfect metabolic efficiency.

Scenario 2: We take an average but pretty active person from the general population who eats a standard diet with plenty of insulin-stimulating carbs, both simple sugars, and complex carbs in the form of pasta, rice, whole grain bread, etc (70% of calories), and who therefore always has high blood glucose and insulin levels, and as a consequence, pretty strong insulin resistance. What happens if they stop eating? We saw this earlier: blood glucose drops, but not insulin; the liver starts to pump out glucose to pick up the slack, and runs out after about 3-5 hours; sugar drops once more, but not really the insulin; since fat stores cannot be tapped into, muscle tissue is broken down to manufacture glucose; longer period of fasting means more muscle breakdown.

If we exercise gently, things are fine at first because we can tap into the glycogen stored in the muscles, but will soon get much worse because we increase the energy demands, but continue to be unable to use body fat stores, and therefore increase the rate at which muscle tissue is broken down, especially if we do weights and high intensity training.

Low intensity aerobic exercise depletes glycogen from the muscles and when it runs out, we feel exhausted, completely flat out. (This is the same as hitting “the wall” in long distance events, and only occurs because the body cannot readily tap into its fat reserves: a well keto-adapted athlete never really hits any such walls!) Far worse is high intensity exercise, which causes more intense and faster muscle breakdown, the higher the intensity, the more muscle breakdown.

Waking up in the morning after a night’s sleep (and unconscious fast), we are starving, dearly longing for the bread, the jams, the cereals, the orange juice, the waffles, the maple syrup, and everything else we can imagine, but we hold out and go to work. Every hour is excruciating, terrible headache, hunger pains throughout the abdominal cavity, but when these subside, we are falling asleep, with a complete inability to concentrate on anything at all. We feel like shit.

By the time evening rolls around, we are so ravenous we would eat a horse. So we sit down and eat, and eat, and eat everything we can get our hands on: pizza, pasta with sauce and cheese, garlic bread with butter, steak and potatoes or french fries, and then desert, sweets, oh man, we waited all day to eat, and now we can eat anything and everything we want, because tomorrow we’ll be starving again for the whole day. We get up in the morning, and the whole cycle starts over again.

Over time we kind of get used to it, but because we don’t understand the most essential element of the whole thing—nurturing nutritional ketosis—we remain just as insulin-resistant, every day we feel shitty, every night we eat like a pig, and throughout the whole time, more or less, we break down muscle, and our insulin resistance prevents appreciable fat loss. After doing this for a while and seeing the detrimental effects of this regime, we go seek help from a fitness expert. They tell us that this intermittent fasting thing is a load of shit, and as them, grow instantly convinced that all the stuff people say about the benefits it can bring for optimal health and improved body composition is also a load of shit: if it didn’t work for me, then it simply cannot work for anyone.

Unfortunately, neither we nor the fitness expert understands enough physiology, biochemistry, and endocrinology to be able to make sense of these conflicting and contradicting accounts, personal experiences, and observations reported in the scientific literature, and just settle into this view that it really is a load of BS, and that it might work a little, sometimes, on some people, but not on others, and no matter what, it always leads to pathological states of mind, if not full fledged eating disorders.

It is my hope, however, that you are now able to see how these very observations, as conflicting, contradictory, and certainly quite puzzling as they may seem at first, can be explained and reconciled marvellously well in light of a better understanding of the basic principles of energy metabolism, and of the remarkable but unfortunately almost universally misunderstood state of nutritional ketosis, that most medical professionals usually mistake for the pathological condition of diabetic ketoacidosis.

Finally, in closing, I have a confession to make: I have been experimenting with intermittent fasting in one form or another for many years now. I never eat anything before midday, and on most days until about 14:00, which makes it an approximately 18-hour fast from 20:00 the night before. On weekends, I fast until noon, and then go do weight training. On those days, I usually eat for the first time around 17:30, and make that my single meal of the day. On some days I eat a large lunch and dinner to increase my overall calorie and protein intake. I usually workout 3-4 times a week, and usually in the late afternoon-early evening.

I have not experienced loss of muscle since I dropped the insulin-stimulating carbs from my diet in 2007. Both muscle tone and strength is maintained very well even after long periods without resistance training. I have, however, never made a particular effort to gain muscle mass. This year, I would like to see how much muscle I can put on, and will thus put the science to the test for myself. If you are interested, don’t worry, I’ll keep you posted. If you’re not, then that’s fine too.

But if there is a single thing you must remember from what I wrote, it is this: you can only really benefit from intermittent fasting when you are keto-adapted, and remain in a state of nutritional ketosis the majority of the time. Otherwise potential benefits are lost, and the practice can become rather detrimental.

hunterslookingoverplain

How long do you think these hunters hunt each day? Do you think they have a big breakfast before going, or a large lunch while they are out? How long do you think they are out before they settle back around the fire in their village to have their main meal of the day? And what do you think they will eat when they do return with their catch of the day?

(This article was written after reading this article by Dani Shugart on T-Nation sent to me by a friend who knew I would have some remarks to make, and probably some clarifications to bring to it.)

How much salt, how much water, and our amazing kidneys

Salt, the one we put on food, is composed almost exclusively of sodium chloride (NaCl) that very easily dissolves in water into positively charged sodium (Na+) and negatively charged chloride (Cl-) ions. And there is something very special and unique about these ions: in our blood, Na+ and Cl- are present in the highest concentrations and maintained in the narrowest of ranges. This is very revealing, and means, quite plainly, that sodium and chloride are the most important  extracellular electrolytes. This is a simple fact. Now, forget everything you’ve heard, been told, or read about salt being bad for you, and consider this:

Our blood is made of red blood cells (45%) and white blood cells and platelets (0.7%) floating in blood plasma (54.3%). Blood plasma shuttles nutrients to cells around the body and transports wastes out. It consists of 92% water, 8% specialised mostly transporter proteins, and trace amounts of solutes (things dissolved or floating in it). And although circulating in trace amounts, the solutes—especially sodium—are vital. The concentration of solutes in blood plasma is around 300 mmol/l (don’t worry about the units for now). In the highest concentration of all is sodium at 140 mmol/l. In the second highest concentration of all is chloride at 100 mmol/l. The sum of these is 240 mmol/l. So, from these numbers alone, we see that blood plasma is more or less just salty water.

glass-of-water

Pure alkaline water

Don’t you find this amazing? Don’t you find it amazing that nobody has ever told you this straight out in this way? And isn’t it amazing that we have been and continue to be told to avoid eating salt because it is bad for us: that it causes hypertension that predisposes us to heart disease? It really is completely amazing and ridiculous and also rather sad. But misunderstandings of this kind are unfortunately much more common than they should, as you may remember from What about cholesterol and Six eggs per day for six days: cholesterol?, but also from Minerals and bones, calcium and heart attacks and A diabetic’s meal on Air France. As you will understand for yourself in a few moments, the problem is not too much salt; the problem is not enough water:

Hypertension is not caused by excessive salt consumption. It is caused primarily by chronic dehydration, magnesium deficiency, and calcification.

Taking a look at the other electrolytes, bicarbonate (HCO3-), the primary pH regulator, is the third most highly concentrated molecule in plasma at 20 mmol/l. Potassium (K+) is the fourth at 4-5 mmol/l, then calcium (Ca 2+) and magnesium (Mg 2+) both at about 1 mmol/l. Therefore, the concentration of sodium in the blood is 7 times higher than that of bicarbonate, 40 times higher than that of potassium, and about 140 times higher than that of calcium and magnesium. And as with everything else in our body’s exquisite physiology, there are very good reasons for this:

Every cell in every tissue and in every organ of our body relies on an electrical potential difference between the fluid inside the cell membrane and the fluid outside of it in order to function: produce energy and transport things in and out. This is particularly important in active “electrical” tissues such as muscles and nerves, including neurones, that simply cannot work—cannot contract and relax in the case of muscle fibres, and cannot fire off electrical pulses in the case of nerve fibres and neurones—without a well-maintained and stable potential across the cellular membrane.

This resting potential across the membrane results from the delicate balance of the equilibrium potential and relative permeability through the cellular membrane of the three most important ions: Na+, K+ and Cl-. The potential is maintained by the sodium-potassium pump: a specialised protein structure in the membrane that ensures the concentration of potassium (K+) stays low outside the cell and high inside the cell, and conversely, the concentration of sodium (Na+) stays high outside the cell and low inside. This is the main reason sodium is so important and why it is so carefully monitored and scrupulously reabsorbed by the kidneys, but there are plenty more.

Obviously, this is not an accident. Nothing about the way our body functions is an accident, and no matter how well a particular physiological function or mechanism is understood or not, we can be confident that it is as perfect and finely tuned as it can be because each and every bodily function is the result of adaptations and refinements over billions of years of evolution. This is not a typo: I really did mean to write billions of years. Because every single cell of which we are made has evolved from all of its predecessors as far back as the very first organic molecules that eventually organised in the very first cell: a group of more or less self-organising organelles that developed a symbiotic relationship with one another just because it benefitted them in some way, and found it safer to cluster together behind a fatty membrane through which they could interact with the outside on their own terms.

The aim of every single self-organising entity, from the simplest virus, bacterium or organelle like the mitochondria (our cellular energy-production furnaces), to highly specialised cells in the brain, in the liver or lining a part of the microscopic nephron tubule of one of the millions of these specialised filtering units in our kidneys, to largest groupings of cells in tissues, organs and systems of organs, has always been and always will be the same: survival. Therefore, to understand living systems objectively we have to understand them from the fundamental perspective of the cell itself, the tissue, the organ and the system of organs itself because every adaptation it undergoes is always aimed at improving its own odds of survival. It is very important to keep this in mind and know that everything that happens in a living system always does so in relation to something else and always for good reason, even when we don’t understand the reason, which in itself is also very important to remember.

I use this opportunity to whole-heartedly recommend Lewis Dartnell’s book Life in the universe. Almost every page for me was a delightful discovery of things I was unaware of and found the book truly illuminating.

Coming back to salt, even though we look mostly at sodium and chloride that are the principal constituents of any kind of salt we put on our food, I very strongly recommend always and exclusively using a real salt: any kind of unrefined sea salt (French, cold water, Atlantic salt is particularly clean and rich in trace minerals), Himalayan salt, Smart Salt or Real Salt (the last two are registered trade marks and very rich in trace minerals). On the contrary, I strongly discourage eating chemically manufactured table salt or even refined sea salt, which are not only stripped of trace minerals found in natural, unrefined salts, but contain varying amounts of chemical additives such as whitening agents, for instance.

Sel-gris_prod

Unrefined sea salt from the Atlantic coast – Sel de Guerande.

Now, without regard for polemical disputes, pseudo-scientific discussions and debates, or otherwise unfounded views and opinions about salt, can we answer the simple question: how much salt should we generally eat? I believe we can, but although it may seem so, it is not that simple a question. So let’s first ask a simpler one:

How do we make a solution with the same concentration of sodium and chloride as our blood plasma?

To answer this our approach is simple: use the mean concentrations of sodium and chloride in the blood to calculate how much salt we need to match these such that drinking our salt water solution will neither increase nor decrease their concentration. It might seem a little technical at first, but bear with me, it is in fact quite simple.

This approach is rather well motivated physiologically because the kidneys’ primary function is to maintain blood pressure and concentration of electrolytes—sodium above all others, and each within its typically narrow range of optimal concentration—while excreting metabolic wastes. The kidneys do this by efficiently reabsorbing most of the water and electrolytes from the large volume of blood that goes through them continuously throughout the day and night, getting rid of as much as possible of the metabolic wastes, and carefully adjusting the elimination of ‘excessive’ amounts of water and electrolytes. (You will soon understand why I placed quotation marks around the word excessive.) Let’s start.

You already know that the mean concentration of sodium in the blood is 140 mmol/l. What we haven’t mentioned is that it must be maintained in the range between 135 to 145 mmol/l. You also know that the mean concentration of chloride is 100 mmol/l, and it must be maintained between 95 and 105 mmol/l. The atomic mass of Na is 23, hence one mole (abbreviated mol) is 23 g, and thus one millimole (abbreviated mmol) is 23 mg. The atomic mass of Cl is 35.5, hence one mole is 35.5 g, and therefore one millimole is 35.5 mg. The molecular mass of NaCl is the sum of the atomic masses of Na and Cl, which implies that one mole of NaCl is 58.5 g, and a millimole is 58.5 mg. (A mole is the amount of substance that contains 6×10^23, Avogadro’s number, elementary entities, in this case, atoms. The molar mass is the same as the atomic or molecular mass.)

Multiplying the concentrations in mmol/l by the molar mass in mg/mmol we get the concentration in mg/l. For Na this equals 140 x 23 = 3220 mg/l or 3.22 g/l, and for Cl it is 100 x 35.5 = 3550 mg/l or 3.55 g/l. This is the mean concentration of sodium and chloride there is in our blood. For a small person like me, weighing, say, 56 kg, there are 4 litres of blood that contain a total of 13 g of Na and 14 g of Cl. This is equivalent to about 2 tablespoons of salt.

It is important to note that this is truly quite a lot in comparison to other ions or molecules in our blood. Glucose, for example, which many—probably most people—mistakenly think as the ‘energy of life’, giving it such great importance, is ideally maintained around 80 mg/dl or 0.8 g/l. This is, therefore, also the amount we would need to add to our salt and water solution to make it have, in addition to that of the salt, the same concentration of glucose as that of our blood. And 0.8 g/l for 4 litres of blood makes a total of 3.2 g of glucose in that (my) entire blood supply. This is about 10 times less than the amount of salt!  What does this tell you about their relative importance in our system?

Now, given that Cl (35.5) is heavier than Na (23), NaCl will have a higher mass fraction of Cl: its mass will be 60% chloride (35.5/58.5) and 40% sodium (23/58.5). This just means that 10 g of NaCl or salt has 6 g of Cl and 4 g of Na. So to get 3.22 g of sodium, we need 8 g of sodium chloride, which provides 4.8 g of chloride.

The simple conclusion we draw from this calculation is that dissolving a somewhat heaping teaspoon of salt in one litre of water gives a solution that has the same concentration of sodium as that of our blood (with a little extra chloride).

Does this mean that we should generally drink such a salt and water solution? No, I don’t think so. Are there times when we should? Yes, I believe there are. But say we drink 4 litres per day, 8 g of salt per litre adds up to 32 g of salt just in the water we drink! If we add even half of this amount to our food, we are looking at about 50 g of salt per day! Isn’t this utterly excessive, especially since we are told by the medical authorities to avoid salt as much as possible, with some people today consuming nearly no salt at all? (This article here takes a sobering look at the evidence—actually, the lack thereof—of the claimed benefits of salt reduction.) And more questions arise: What happens when we eat less salt? What happens when we eat more? What happens when we drink less water? What happens when we drink more?

Eating more or less salt. Drinking more or less water.

Remember that the kidneys try very hard to maintain the concentration of solutes in blood plasma—to maintain plasma osmolarity. Also remember that sodium is by far the most important in regulating kidney function, and it is also in the highest concentration. It is nonetheless total osmolarity that the kidneys try to keep constant, and besides sodium, the other important molecule used to monitor and maintain osmolarity by the kidneys is ureathe primary metabolic waste they are trying to eliminate.

As an aside to put things in perspective about the importance of sodium, plasma osmolarity is typically estimated by medical professionals using the sum of twice the concentration of sodium with that of urea and glucose: calculated osmolarity = 2 Na + urea + glucose (all in mmol/l). Since sodium is typically around 140 mmol/l whereas glucose is less than 5 mmol/l and urea about 2.5 mmol/l, it’s obvious that we could just forget about the latter two whose contribution is less than 3% of the total, and look exclusively at sodium concentration (2 Na = 280; glucose + urea = 7.5, so their contribution is 7.5/(280+7.5) = 2.6%).

Eating anything at all, but especially salt or salty foods, raises plasma osmolarity. In response—to maintain constant osmolarity—the kidneys very efficiently reabsorb water and concentrate the urine. Drinking water dilutes the blood and therefore lowers its osmolarity. In response, the kidneys very scrupulously reabsorb solutes and eliminate water, hence diluting the urine.

If we eat nothing and just drink plain water, beyond the body’s minimum water needs, every glass will dilute the blood further and thus cause the kidneys to try to retain more of the sodium while eliminating more of the water. We are drinking quite a lot, but as the day progresses, we are growing more thirsty. We drink more but go to the bathroom more frequently, our urine grows more diluted, and by the end of the day we find ourselves visibly dehydrated, with chapped lips and dry skin. This seems paradoxical in that while drinking water, we are getting increasingly dehydrated. But it is not paradoxical. It is simply the consequence of the kidneys doing their work in trying to maintain constant blood plasma concentrations of sodium (and solutes). For those of you who have fasted on plain water for at least one day, you mostly likely know exactly what I’m talking about. For those who have not, you should try it and experience this first hand for yourselves. Avoiding dehydration in this case is simple: eat salt to match water intake.

If, on the other hand, we do not drink, then the blood gets more and more concentrated, the concentration of sodium and other ions, urea, and everything else for that matter, rises with time, and the kidneys keep trying, harder and harder with time, to maintain the osmolarity constant by retaining as much as they possibly can of the water that is present in the blood. You might think: why not just eliminate some of the solutes to lower their excessively high concentration? But eliminating solutes can only be done through the urine, which means getting rid of water that, in this state of increasing dehydration, is far too precious, and the kidneys therefore try to retain as much of it as possible, hence concentrating the urine as much and for as long as possible to make full use of the scarce amount of water that is available for performing their functions. But here is a crucial point to understand and remember:

In order to reabsorb water, the kidneys rely on a high concentration of solutes—hyperosmolarity—in the interstitial medium through which passes the tubule carrying the filtrate that will eventually be excreted as urine. This is how water can be reabsorbed from the filtrate: the higher the difference in concentration, the more efficient the reabsorption. If there is plenty of excess salt—sodium and chloride ions—then these solutes is what the kidneys prefers to use to drive up and maintain the hyperosmolarity of the interstitial medium, and urea can be excreted freely. If, however, there is a scarcity of sodium and chloride ions, then the kidneys will do everything to reabsorb as much of the precious ions that are in circulation to maintain adequate concentrations of these in the bloodstream, and at the slightest sign of water shortage and dehydration—to ensure the hyperosmolarity of the interstitial medium for maximum water reabsorption—the kidneys will begin to recycle urea, excreting progressively less of it as dehydration increases.

Most of you will have experienced a long day walking around, maybe while on a trip visiting a city, during which you did not drink for several hours. You might have also noticed that you probably didn’t go to the bathroom either, which you may have found unusual compared to the frequency with which you usually go pee when you’re at home or at work. You will have noticed that your mouth was drier and drier as the hours passed, but also that you felt more and more tired, heavy-footed and without energy.  Eventually it struck you just how thirsty you were, or you were finally able to find water to drink, and drank to your heart’s content. As you drank, you might have felt a surge of energy within as little as a minute or two or even immediately following the first few sips. Soon after, you finally did go to the bathroom, and noticed how incredibly dark and strong smelling your urine was. Now you understand what was happening in your kidneys, why you didn’t go pee for these long hours, why your urine was so dark and smelled so strong. However,  the reason why you felt your energy dwindle as the hours passed, and then return when you drank is still unclear.

Water in the blood regulates its volume. And volume in a closed system determines internal pressure. Our circulatory system is a closed system in the sense that there are no holes where blood either goes in or comes out. Yet at the same time it is not a closed system because water enters and leaves the system: it enters the bloodstream through the wall of the intestines, and leaves it through the kidneys and out into the urine. All physiological functions depend intimately on blood pressure: whether it is shooting up through the roof as we face a huge brown bear towering over us and growling at the top of its lungs, and priming us in this extremely stressful fight-or-flight situation for some kind of high-energy reaction in response, or whether it is as low as it can be during our most soothing and restful sleep deep into the night, when the body is repairing and rebuilding itself. And what is the primary regulator of blood pressure? The kidneys.

I will address the details of how the kidneys function and regulate pressure and osmolarity in another post. For now, what is relevant to understand why your energy faded as the hours passed or, more precisely, as the body got progressively more dehydrated, is straight forward:

As water content decreases, blood volume decreases. As the volume decreases, blood pressure drops. And as blood pressure drops, energy levels go down. It’s as simple as that.

It does not help that as soon as the kidneys detect dehydration and drop in pressure, they release hormones to provoke the contraction of the blood vessels in order to counter the pressure drop. This works to a great extent, but since the arteries and veins are constricted, blood flow throughout the body decreases, which in turn contributes significantly to our feeling increasingly heavy-footed and sleepy. With every passing minute, dehydration increases, pressure decreases, blood vessels contract more and our energy level drops further, to the point where we just want to sit down, or even better, lie down, right here on this park bench, and have a long nap.

Interesting, isn’t it? And here again there is nothing strange or paradoxical in this self-regulating mechanism that eventually puts us to sleep as we get increasingly dehydrated. It is simply the consequence of the kidneys doing their work in trying to maintain constant osmolarity and blood pressure. Avoiding dehydration in this case is even simpler: drink water.

If you’ve read this far, you know that both solutions to prevent dehydration are intimately linked: if we don’t drink enough water we get dehydrated, but if we drink too much water without eating salt we also get dehydrated. So let’s now ask another question:

Precisely how much water?

An adult human being needs on average a minimum of 3 litres of water per day to survive for more than a few days (Ref). This depends on climate and level of activity and a bunch of other factors, but in general the range is well established to be between 2 litres in cooler and 5 litres per day in the hottest climates. As suggested from our previous considerations, minimum water intake is also related to salt and food intake. And although this was obvious to me from my own experience of fasting rather regularly between 1 and 3 days at a time, I had not read about it. But as it turns out, the NRC and NAS both (independently) estimated minimum water intake as a function of food intake to be between 1 and 1.5 ml per calorie. For a diet of 2000 calories this would amount to between 2 and 3 litres. But this obviously does not mean that if we don’t eat anything, we don’t need any water! So, what is the very strict minimum amount of water the body needs before physiological functions break down? The short answer is 1.1 litres. For the slightly longer answer, here is a excerpt from page 45 of The Biology of Human Survival:

If obligatory losses are reduced to an absolute minimum and added up, the amounts are 600 milliliters of urine, 400 milliliters of insensible skin loss, and 200 milliliters of respiratory water loss, a total of 1.2 liters. Because maximum urine osmolarity is 1200 milliosmoles/liter, if diet is adjusted to provide the minimum solute excretion per day (about 600 mOsmol), minimum urine output may fall, in theory, to 500 milliliters per day and maitain solute balance. Hence, the absolute minimum water intake amounts to just more than 1 liter (1.1) per day.

(This is also taught in renal physiology lectures such as this one. If you are interested, you will learn a lot from this longer series of 13 segments on urine concentration and dilution here, as well as from this series of 7 segments on the renin-angiotension-aldosterone system here. I found all of them very instructive.)

Keep in mind that 1100 ml of water per day is the very bare minimum for survival, and that there are absolutely no other water losses: basically, you have to be lying, perfectly calm and unmoving at an ideal room temperature where you are neither hot nor cold, not even in the slightest. That’s not particularly realistic unless you’re in a coma. And to show just how extreme it is, let’s see how much of the water the kidneys need to reabsorb to make this happen:

For someone like me weighing 57 kg, the mass of blood is 57*7% = 4 kg. Since the density is almost equal to that of water, 4 kg corresponds to 4 litres. Of this, we know that plasma accounts for a little more than half (54.7%) by volume which makes 2.2 litres, and since plasma is 92% water, the volume of free water in the blood supply is almost exactly half: 2 litres. Blood flow through the kidneys is, on average, around 1.2 l/min. This amounts to more than 1700 litres per day, and means that for 4 litres of blood in the body, every drop of blood goes through the kidneys 425 times in 24 hours, each and every day.

In the kidneys the first step in filtration is the “mechanical”, particle-size-based separation of the blood’s solids from its liquid component. Water makes up half the blood volume, and therefore represents half the flow through the kidneys: 0.6 l or 600 ml/min (850 litres per day). But only 20% of the total flow goes through nephron filtration, which makes 120 ml/min. In the extreme case we are considering, urine output is taken to be 500 ml in 24 hours, equivalent to 20.83 ml/hour or 0.35 ml/min (500 ml/24 h/60 min). Therefore, to achieve this, the kidneys must reabsorb 119.65 ml of the 120 ml flowing through them every minute. This translates to an astounding 99.7% reabsorption efficiency! I’m very skeptical that your average person’s (generally compromised) kidneys could achieve this, but the point was to quantify how extreme this situation at the limit of human survival really is, and as you can see, it is indeed as extreme can be.

Also, keeping in mind that these minimum vital physiological water losses in these circumstances would occur at a more or less uniform rate throughout the day, it would probably be much better to drink a little at regular intervals during our walking hours than to drink everything at once and nothing else during the remaining 24 hours. But what would be the ideal rate at which we should replenish our water in these extreme circumstances?

Assuming the theoretically minimum combined water losses of 1100 ml are lost evenly over the course of the 24 hours, this corresponds to a water loss rate of 0.76 ml/min (1100 ml/24 h/60 min). This is therefore the ideal rate at which to replenishing it. In practice, we may not have an IV system to do this for us, and we will probably be sleeping long nights as our heart rate and blood pressure will have hit rock bottom. Drinking 1100 ml in 11 hours (to work with round numbers) could be done by taking 100 ml, (half a small glass), every hour. This would be the simplest and most reasonable way to maintain solute balance as best we can.

Naturally, with such a minimal water intake, the kidneys are struggling to maintain osmolarity by retaining as much water as possible. Any additional intake of salt (or food) would make things worse in the sense that it would raise the concentration of sodium (and solutes) in the blood whose balance the kidneys will not be able to maintain without additional water. But remember that eating a 200 g cucumber, for example, supplies nearly no calories as it contains virtually no sugar, fat or protein, while proving almost 200 g (ml) of water. And that, conversely, any drink containing caffeine or alcohol will actually dehydrate as those substances are diuretic and cause the excretion of free water.

A somewhat more realistic scenario is one in which we are not eating, but very moderately active at comfortable temperatures. In this case, most experts would agree that the minimum water requirements would be around 2 litres per day. Since we are fasting, these additional water needs are due to greater water losses through evaporation and physiological activity; not to offsetting increased water needs due to food consumption. Consequently, we should ideally drink about 10 glasses of 200 ml, one approximately every hour from 7h to 19h, and we should not eat any salt.

More realistic but still not so common, is that you are doing a 24 hour fast. The purpose of the fast is to give a break to the digestive system, rehydrate bodily tissues, stimulate more fat burning and flush toxins out of the system. Say we drink 4 litres instead of the minimum of 2. In this case we should, in fact, eat some salt in order to ensure good hydration of tissues by supplying plenty of water through a well hydrated bloodstream without diluting the sodium and thus causing the kidneys to excrete more water. And this brings us back to the basic question that set us on this rather long  investigation:

Precisely how much salt?

But you already know the answer to this question: 1 teaspoon per litre in 2 of the 4 litres. Because we don’t drink during the night for about 12 hours, the body inevitably gets dehydrated. Therefore, the best strategy is to start with plain water to rehydrate the concentrated blood and bodily tissues dehydrated from the night, and end with a litre of plain water in preparation for the dry night coming. You should take the equivalent of 1 generous teaspoon of salt with each of the additional litres of water during the day. This will ensure proper hydration of tissues by preventing excessive dilution of blood sodium levels, and maximum urea excretion. Excess sodium, chloride and any other electrolyte will be readily excreted in the urine.

Finally, the far more realistic scenario and, in fact, the one that for most of us is the everyday, is that we are normally active and eating around 2000 calories a day, typically over the course of about 12 hours. In this case we need the basic 2 litres to offset minimum evaporation and physiological losses, and between 2 and 3 litres to offset the 2000 calories. This makes between 4 and 5 litres, 2 of which must be plain water, and 2 or 3 of which must be matched by a good teaspoon of salt per litre that will most naturally, and maybe also preferably, be taken with the food.

Keep in mind that this is the total salt requirements and many prepared foods contain quite a lot already. The hotter or drier the climate, the more water we need. The more we exercise, the more water and the more salt we need. The more we sweat, the more water and the more salt we need. The more stress we experience, the more water and the more salt we need. And in all of these cases, we also need a lot more magnesium.

By the way, it is interesting but not surprising that this conclusion on the amount of salt per day: about 10-15 g, is also the recommendation of the late Dr Batmanghelidj, the “Water doctor”, as well as that of Drs Volek and Phinney, the “Low-Carb doctors” (see References  for details), although the former emphasises the importance of an abundant water intake, while the latter hardly mention it if at all.

So this is it. We know how much water we should generally drink, and we know how much salt we should generally eat:

We should always drink the bare minimum of 2 litres per day. Ideally we should drink 4-5 litres every day. If for some reason we drink 2 litres or less, we should not take any salt (or food for that matter!). If we drink more than 2 litres, we should match each additional litre of water with 1 teaspoon of salt, taking into account the salt contained in the food we eat. It is always better physiologically to drink more than to drink less. And remember that we hydrate most effectively on an empty stomach by drinking 30 minutes before meals.

A diabetic’s meal on Air France

A few days ago, I was updating a reservation on the Air France website in anticipation of my trip from Madrid to Toronto on my way to the Origin of Stars and their Planetary Systems conference at  McMaster University. Looking through my personal profile, I found a section where to define a preference for the meals served on long flights. Looking through the list, I was intrigued by the “Diabetic” option.

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The fact is, I’ve read more than I ever intended about diabetes. That’s because the authors of most, if not all books that relate to natural health and nutrition in some way or another, usually have something to say about diabetes, more specifically, insulin-resistant or adult-onset or type II diabetes. One simple reason for this is that diabetes is so widespread in the populations of industrialised countries that it is almost ubiquitous. Another reason, certainly just as important if not more, is that the most common causes of death in industrialised countries—heart disease, stroke, alzheimer’s and cancer—are all much more common in diabetics than they are in non-diabetics, and in all cases, several-fold more common. Doesn’t this very naturally suggest that there is a fundamental relationship between insulin-resistant diabetes and these other conditions? Maybe even that what causes the development of the diabetic condition also causes the development of the others?

Type II diabetes, also called adult-onset diabetes, should instead always be referred to insulin-resistant diabetes in order to highlight the actual problem—insulin resistance. Unfortunately, it is only rarely referred to as such. Insulin resistance is a description of the state of a cell that does not allow insulin through its membrane to carry glucose to the inside of the cell—it resists insulin’s plea to let the glucose enter. The consequence of this is high levels of blood-glucose and insulin that don’t drop down as they should to acceptable, let alone ideal physiological levels. In fact, as far as I know, the primary, if not the only criteria used by  most MDs to diagnose the onset of diabetes is blood-sugar levels. It is considered normal to have blood-sugar levels anywhere between 65 and 110 mg/dl, but at 120 or above we are considered at risk of developing diabetes.

Interestingly, although fasting insulin concentration is a much better, more robust, indicator of not only the condition of insulin-resistant diabetes, but also of the gradual development of it, which does not appear from one year’s blood test to the next but rather develops over an entire lifetime, slowly and surely, it is almost never performed in standard blood tests ordered by general practitioners. It should.

And why is it better? Because instead of being subject to large fluctuations due to a myriad of different factors as is blood-sugar, such as carbohydrate intake, stress and physical activity, for example, fasting insulin is much more stable, decreasing steadily over the course of several hours, and reflects well the overall state of insulin resistance or sensitivity of our cells.

There is another more direct and accurate way of testing insulin sensitivity that involves measuring blood-sugar and insulin concentrations at regular intervals after ingesting a large amount of glucose. But this method is much more involved and lengthy. Fasting insulin is simple, easy, accurate and cheap. It really should always be done in standard blood tests. Request it on your next blood test. Although, if you follow the dietary advice on this blog, you should never even have to think about getting any blood tests done at all. I just do them because I find it interesting.

I discussed the insulin mechanism in We were never meant to eat simple or starchy carbohydrates, and also in When you eliminatie insulin-stimulating carbohydrates. But for just a second, forget what you remember about it, and consider the following:

Insulin is necessary to clear out excess sugar in the blood: it is the hormone that regulates fat storage. The greater the amount of sugar, the greater the amount of insulin required, and the greater the fat storage. The more often there is sugar, the more often insulin is needed. Insulin resistance in cells develops over time due to over-exposure to insulin, snack after snack, meal after meal, day after day and year after year.

Would we not then immediately conclude that in order to avoid developing insulin resistance we simply and straight-forwardly need to avoid raising blood-sugar levels? Furthermore, would we not immediately hypothesise that in order to reverse insulin resistance and regain insulin sensitivity we need to do just that: avoid raising blood-sugar levels? And how might we do that? You already know this: by not eating simple or starchy carbohydrates. Instead, eating most of our calories from fat to provide all the energy and calories needed for healthy cellular and hormonal activity throughout the body, and never or rarely be hungry.

Now, what was I served as the special order diabetic meal on the flight from Paris to Toronto that I am still sitting on? The salad was of grated carrots sprinkled with super dry, also kind-of-grated white meat, either of chicken, turkey of tuna, (I can’t tell because it didn’t have a smell and I don’t eat meat, so I didn’t taste it). The main course was of a piece of super-dry white fish on a bed of pre-cooked, dry, white rice with boiled frozen ripple-cut carrot slices. This was accompanied by not one of the classic crusty, refined white flour, mini-baguettes they serve on Air France flights, but by two of them. There were also two deserts, a small, dry-baked apple cut in two halves, and a soy-based pudding-like desert. Needless to say that I didn’t eat much of this meal. It was an experiment anyway: I was curious to see what a diabetic would be served, and now I know.

Before reading the next sentence, could you now tell me what is the main characteristic of the meal I just described?

It is a low-calorie, low-protein, super-low fat meal. As a consequence, it is a very high carbohydrate meal: there’s obviously nothing else it could be. Well, that’s not quite true: it is a very low-mineral and enzyme content meal, highly processed and totally dead. But that’s not really important, right? Only calories are important, right? And it is only important that it be low-fat, right?

Therefore, a diabetic that goes to the effort of ordering a special meal instead of the standard menu will end up consuming less protein, a lot less fat, and a lot more carbohydrates. This will cause a much greater rise in blood-sugar levels, that will in turn cause a much greater rise in insulin, and in the case of most diabetics will, in fact, require the injection of additional insulin because their cells are already mostly insulin-resistant. This will inevitably cause increased insulin resistance. But to make matters even worse than this already is, because they are eating very little fat, they will be increasingly hungry after each meal, and thus tend of overeat every time they get the chance. And overeat what? … carbohydrates. This is the definition of a vicious cycle. How sad. How incredibly sad.

I was just offered by second meal: it was pretty much the same thing with a cold dry meat salad instead of the re-heated dry fish with rice dish. What a laugh. This time, I just turned in down.

Oh, and by the way, the first meal was frozen almost solid. Every component, including the carrot salad, baked apple, soy desert and water: everything except for the main course that had been heated. And the second meal was also frozen, but this time, the air flight attendant felt quite sorry about it, and was rather sheepish when offering it to me. How funny! It’s a good thing I am used to fasting.

Probiotics, chlorella and psyllium husks

Essential for building and maintaining a healthy digestive system, it is best to take probiotics and chlorella on an empty stomach, once to several times per day, to maximise the bacterial flora replenishing from the probiotics, and the prebiotic as well as cleansing and heavy metal chelating effects of the chlorella. This way, there is minimal potential damage to the probiotics by acidic gastric juices secreted into the stomach when protein is present.

Psyllium are also good to take on an empty stomach or with foods that are not mineral-rich (as in a coconut milk pudding, for example), in order to maximise their intestinal cleaning and minimise their possible interference with mineral absorption. It is most important for the psyllium husks to be completely saturated with water before taking them to avoid causing cork-like condensations of psyllium husks in the gut.

All supplements should be of the highest quality. I buy probiotics from Prescript-Assist, chlorella from Dr. Mercola, and psyllium husks either whole or powdered but organically grown without pesticides or herbicides from Frontier.

If you have not taken these supplements, then your digestive system will be in dire need of them. It would be best, in addition to the morning probiotics, chlorella and psyllium husks, to take probiotics and chlorella with 500 ml about 30-45 minutes before eating at lunchtime, and again before dinner. After even 1 week, you will feel much better. After about 1 month, you can reduce the frequency to twice per day, and eventually you can take your probiotic only in the morning.

For the chlorella,  it’s important to not take too much at first because the detox could be too fast, and this would stress the body unnecessarily and make you feel unwell as well as make your stools runny. Once you have past the initial detox phase, you can and should take chlorella as often and as much as you want depending both on the circumstances and on your needs.

I, for example, sometimes take at 15 little pellets (3 grams) per day in two or three doses, 30 minutes before meals. But on my weekly, 24-hour fast, (usually on Mondays), during which I only take water and herbal teas, unrefined sea salt and chlorella from Sunday evening after dinner, until Monday evening before dinner, I take at least 30 little pellets (6 grams) of chlorella over the course of the day, and sometimes more. This not only gives the body easily digestible essential amino acids, but also supplies a lot of essential minerals, chlorophyl, and detox power, which is, after all, the main purpose of the fast.

The quantity of the psyllium husks should be 1 teaspoon per day for the first week. Then 2 teaspoons, and eventually 3 teaspoons per day, but not more: it’s not necessary and this much fibre may stress your digestive system, which is obviously not what you are trying to do. After a month, you should reduce the quantity of psyllium to one teaspoon per day, and see if you can reduce it further to every other day, depending on the effects on your digestion. I personally usually take 1 teaspoon almost every day to maintain perfect intestinal transit and  stools (regular, easy to pass, and almost nothing to wipe). In any case, you can not do yourself harm by taking psyllium husks with plenty of water on a regular basis (unless you are allergic to it, which is very rare); instead it will be of great benefit.

The best way to know how much and how often you need to take is by carefully monitoring the smell of your breath—it should be fresh and odourless throughout the day and night; the smell of your sweat—it should also be light, not acidic smelling, and basically odourless, even if you don’t shower for a couple of days without using deodorant or perfume; and finally, the regularity, consistency and smell of your solid eliminations—they should not be too hard nor too soft, voluminous, easy to pass, and easy to wipe. Ideal stools pass easily and do not need any wiping. This is what we should strive for by making adjustment to our water intake, cooked versus raw food intake, psyllium and vegetable fibre intake, paying particular attention to the timing of these with respect to one another.

Doing these simple things you will very quickly feel much better, and also begin to notice and understand much more about the natural detox functions of your own body, with its daily cycles as well as with its particularities. In physiological function, we are all basically the same with small individual differences that must be first identified and then tended to with care, patience and attention, being especially mindful of their evolution in time and depending on the changing circumstances. Only we ourselves can really learn how to do this, and so we must if we want to achieve and then maintain optimal health throughout our life, as we age and mature.