Initial conjectures related to life span on a ZC/VLC diet
By and large, carnivorous mammals across the world exhibit lower average lifespans than omnivorous creatures. This may be due to countless variables, but the fact that these creatures survive for smaller periods of time may indicate that mammalian bodies are not well-adapted to purely carnivorous diets, even when the carnivores have been consuming such diets for a very long time. Further, archaeological records have demonstrated that only about 25% of early humans and Neanderthals made it beyond 40 years of age. We should take into account the fact that Neanderthals and early humans were known to have consumed predominantly carnivorous diets, and that the ice age during the Neanderthal’s reign probably made the routine consumption of plant-based foods difficult. The following text critically questions the value of a ZC/VLC diet in relation to optimal human performance. If a ZC/VLC diet is not optimal for a human, then the lower life span (and increased brain size) of these ancient humans may be justified by their decreased access to abundant plant foods. Note: I will use VLC/ZC to refer to diets that consistently contain less than 30g carbohydrates on a daily basis.
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For any intrigued readers, here is what I am doing at the moment to respond to heart issues following a fairly lengthy zero carb/very low carb diet. I have included the carefully thought-out conclusions that I arrived at to justify my actions.
After dealing with my problem, and reading up on a great deal of scientific studies and informal experiences, I've decided to cut the ZC (well, ZC insofar as there weren't any plant foods, for there were certainly a healthy amount of organs) experiment short, and start consuming a reasonable amount of carbs per day (50-100g).
Why?
The body is an intricate series of processes that are disjointed, collaborative, and oftentimes unpredictable. Historically, humans have adapted to our environments in curious manners. Any mono diet (even a near-perfectly calibrated mono meat diet) has the tendency to deal with corporal processes in a similar manner to the dreaded techniques of Western medicine: in a homogenizing, mechanical fashion. Let me unravel this bold assertion.
The following
three dilemmas are fairly in alignment with the "old friends" theory that Paleophil has presented on these forums for quite some time. His call to challenge chronic ZC should intelligently be taken into consideration in light of the emergence of certain questionable physical circumstances for numerous offal-ingesting, carnivorous ZCers (myself included.) I will tie these three dilemmas into a cohesive argument at the end of this post.
First dilemma: Evolution, rapid brain expansion, and the historical transition to a predominantly carnivorous lifestyle
Having studied evolutionary anatomy, I can confidently say that the human body has not evolved in an
absolutely unified manner throughout the last few millennia. If we believe the scientific disciplines (that most of us agree with on some points) in arguing that humans were primarily plant-eaters before carnivores, and that our brains became much larger during our carnivorous days, then we arrive at a conundrum: the expansion of the human brain's size occurred very rapidly, evolutionarily speaking. This initial expansion happened because a primarily herbivorous species (ancient humans equipped with a plant-oriented bacterial flora and bodily qualities prepared to metabolize plant-foods) chose to substantially increase their raw meat consumption, viz. hunting and scavenging. In response to--and in consequence of--heightened meat intake and anatomical specificities (opposable thumbs, etc.), the human brain became incredibly refined and potent. We are obviously still basking in the brain-expanding glory of this momentous carnivorous evolutionary trajectory; albeit, of course, we should question for how long we will be able to do this, collectively, considering the quality of the modern human's diet (namely, the absence of raw meats/fats/offal, as well as the presence of genetically modified, anti-nutrient-laden plant-foods.) The point here is that the enlargement of the human brain occurred, at least in an evolutionary time-scale, at an accelerated and atypical rate. Such an expansion of cognitive functions was atypical in that it
did not reflect directly on our physical bodies; we did not grow massive fangs or claws to hunt down and slaughter large game; rather, we created tools, and used our newfound intellectual abilities to skillfully dispose of our subjects. Similarly, other attributes of our bodies did not evolve as quickly as our brains. Which brings me to the second dilemma.
Second dilemma: The divergent evolution hypothesis (similar to the ‘old friend’ theory)
Bacterial processes in the body account for much of the health of the human. The inhabitants of our gut flora, for one, provide us with the accoutrements necessary to digest nutrients, synthesize vitamins, neurotransmitters, and immune cells. Other bacterial-human symbiotic relationships offer what is a long list of relatively unexplored, distinctive benefits for organ systems (bacteria on the skin serve specific functions, and so on.) For the most part, the bacterial microbiome of the body is at the core of the animal’s ability to function properly. Without an optimally functioning microbiome, the human is exposed to dire environmental dangers that will rapidly deteriorate living systems. This truth has been demonstrated by numerous studies on the importance of a thriving microbiome, and the functionality of different gut floras is specifically being researched at the moment by the human microbiome project (which I urge all of us to look into, if even for the sole sake of criticism.)
Back to the brain. If we agree that the human brain indeed expanded in such a rapid manner—as is evidenced by the archaeological record—and that ancient humans decided to maximize meat intake at the potential expense of plant-foods, then what we must recognize is that the human microbiome (that is, the bacterial underpinnings of the body, such as the gut flora and other bacterial agents) of the ancestral, predominantly herbivorous humans, more likely than not failed to properly catch up to the accelerated evolution of cognitive structures—mainly because the microbiome had no need to catch up; ancient humans were still consuming at least some plant-foods. What occurred, in effect, was that the enduring plant-dependent (in that they had thrived on plant-foods for millennia) bacterial entities within the ancient human bodies were quickly, over the course of a few thousand years, forced to confront a vastly different set of digestive demands—those of predominantly carnivorous diets—in order to properly account for the newly-modified consumption practices of the rapidly changing humans. In response to such evolutionary stressors, the human microbiome, which was at one moment well-adapted to an optimal herbivorous functionality, cracked, adapted, and ceded to carnivorous demands.
The cracks and adaptations exhibited by a historically herbivorous human microbiome as it collides with a carnivorous ZC/VLC diet have appeared for different dieters in interesting forms (specifically on these forums.) Personally, I dealt with heart issues, constipation, diarrhea, and reduced bowel movements at different points throughout my VLC/ZC experiment. I followed the diet as properly as possible: minimized raw protein, increased fat, ate lots of raw offal, etc. The diarrhea and constipation were sparse, but the reduced bowel movements were constant. I attributed this, as many others have done, to the supposedly commonsensical reduction of bowel contents on a raw ZC/VLC diet. But soon I realized that even on a low fiber diet, feces is not constituted primarily by metabolic waste: feces is predominantly bacteria by mass. This made me seriously question the underlying implications of the assertion that excrement inevitably decreases when ZC/VLC. What seems to be decreasing on a ZC/VLC carnivorous diet is the actual mass of the bacterial entities in the gut. The livelihood of these organisms, which evolutionarily have remained dependent on the human’s consumption of plant-based foods, is put in peril by the absence of plant-based products.
Some will argue that the human gut flora—only a single aspect of the microbiome, but indubitably the most important—does not need plant-based foods to survive; these same people might argue that the herbivorous gut flora hypothesis is merely a myth: that humans on a ZC/VLC diet can simply reconstitute their gut floras, and create a purely carnivorous microbiome. There is no evidence to support the claim that the human gut flora, evolutionarily and historically nurtured by plant-based foods, thrives under carnivorous ZC/VLC conditions. In fact, there is a striking amount of evidence to the contrary.
According to recent research compiled by Dr. Jeff Leach, the gut flora of chronic LC dieters demonstrates fairly poor traits in relation to known optimal conditions. Truly, what we know about gut floras in rather limited compared to our general anatomical knowledge, but the fact remains that serious changes are occurring in our guts when we drastically reduce the intake of carbohydrates. These changes, taken in total and observed anecdotally and scientifically, seem to point toward a reduction in the total numbers of bacterial symbiotic agents in the guts of ZC/VLC subjects.
Third dilemma: ketosis, gluconeogenesis, brain glucose requirements, and the optimal human diet
There are numerous indicators and pieces of evidence that corroborate the above hypothesis concerning the fragmented evolution of the brain in relation to the rest of the body. In order to properly dispel the myth that ZC is the optimal human state, we will first need to consider a variety of arguments. To begin with, let’s analyze the main metabolic structures involved in the ZC diet--gluconeogenesis and ketosis--and their different properties in relation to the human brain.
A) On a very basic level, scientific studies of the brain demonstrate that it demands a certain amount of glucose each day. When in a
deep ketogenic mode (as most ZC dieters are), the brain refuses to consume 100% glucose, and demands that the liver produce glucose for its minimum sustenance requirements viz. gluconeogenesis—a process which many of us are familiar with, and which involves the cleaving of amino acids to generate glucose. Gluconeogenesis is a liver-intensive process that is modulated by glucagon, cortisol, insulin, and various other interconnected hormonal pathways. The very fact that gluconeogenesis is associated to cortisol levels should send up some red flags: gluconeogenesis is tough work, and our bodies will avoid activating the metabolic pathway unless absolutely forced to do so. In fact, glucose is stored as glycogen in fairly high quantities (around 500-1000+ calories, depending on the person) in the liver, brain, and to a lesser extent, in muscles, to prevent the body from having to generate glucose via gluconeogenesis. It is evident from the body’s attempts at quarantining and preserving glucose that it does not want to have to turn water into wine (protein into glucose) constantly. Functionally, the body is far more interested in granting the brain its glucose requirements without overstressing the liver, which is already responsible for enough metabolic processes. This makes sense, because sugars aren’t too difficult to come by in most environments (arctic north excluded, but we’ll tackle that in a moment), and there’s no reason why the brain should be denied its 30g of glucose per day. Unless, of course, something has gone wrong.
B) In the deep ketogenic near-total absence of glucose, the body engages in gluconeogenesis and, to a lesser degree, the production of glucose from fatty acids, to supply the brain with its minimum glucose needs. Both are relatively tolling tasks compared to the simple absorption of free-floating blood glucose, or the consumption of glycogen for glucose. And what about the other organs? When in a deep ketogenic state, the heart will effectively utilize ketone bodies for energy, as will most other organs (although the heart itself prefers fatty acids, which haven’t been cleaved into ketones.) The functionality of the non-brain organs while in deep ketosis isn’t much of a surprise, considering that ketosis is an ancient metabolic state, and the body evolved to withstand ketogenic periods for a fair amount of time (in order to support the probable nomadic lifestyles and difficult environmental conditions of our predecessors.) Despite the capacity of the organs to utilize ketones effectively for extended periods, the brain will continue to refuse to convert entirely to a 100% ketone-driven mode. Of course, having to produce only 30g of glucose per day via gluconeogenesis is not a dire or critically exhaustive task. Carnivorous ZCers and very, very LCers will argue that this is not a stressful process at all; it is natural and beneficial. The specific stress of the generation of 30g of glucose via gluconeogenesis is not particularly relevant for my argument. Instead, the main issue here is that even when a body is in deep ketosis, the brain refuses to sacrifice its glucose requirements entirely, and it will call upon a strenuous metabolic pathway to make certain that its own needs are satisfied. The brain demands glucose—not ketone bodies. If ketosis were the default and optimal metabolic state of the human body, then why would the brain make such absurd demands?
There is a simple explanation for this: deep ketosis is not the human’s default and optimal metabolic state. We arrive at this conclusion by determining that the human’s dominant organ, the brain, refuses to survive on ketones alone, and the body will go to great extents to quarantine and protect glucose reserves, as well as produce its own glucose when no other sources are available. Instead of conceiving of deep ketosis as a default optimal state, I encourage you to understand that ketosis is a metabolic state which is mobilized to deal with the sustained absence of an organ system’s minimum nutritional/glucose requirements, and which serves to heighten certain physical processes to facilitate the procurement of the nutritional agents needed for the production of said glucose needs.
Nutritional agents come in one of four forms:
1) Through the consumption of a large protein-heavy meal (not favorable, because then the body will need to switch on gluconeogenesis to make glucose from the protein that remains after feeding core skeletomuscular processes, and the excess protein will need to be excreted via the kidneys to prevent toxicity, which may place a large stress on the urinary system.) Note that various ZCers and very LCers have dealt with kidney stones in the past, and that the carnivorous ZC/ultra VLC diet typically calls for abhorrent amounts of daily fluid intake (wholly against what would be expected in a non-domesticated environment.)
As an added note, in the absence of glucose, the body calls on the kidneys to flush out stored water and electrolytes from cells (the reasons for this are various. My personal perspective is that, on a fundamental level, the body releases water because it wishes to be lighter so as to make long distance traveling while in a deep ketogenic state easier.)
2) Through the activation of the TCA cycle, and the marshaling of the acetyl-COA metabolic chain, following the consumption of a large fat-heavy meal without protein (not favorable for similar reasons as above, and in fact rather unnatural, considering that fat is almost always found with some protein.)
3) Through the ingestion of carbohydrates. (Simple, basic, and clean. Breakdown of glucose occurs in the animal cells themselves in a direct and rapid process which involves commonly discussed hormones.) Water is the end result of the burning of carbohydrates. The ingestion of carbohydrates to meet the brain’s minimum requirements is favorable because the liver does not need to actively reconfigure amino acids to produce sugar, and it is involved in this process only marginally through the storage of excess glucose, the secretion of hormones, etc.
4) Through the breakdown of body fat and lean protein tissues. (Not optimal for obvious reasons. The body does not want to consume itself. This is a desperation measure.)
Summary of dilemma #3: The human brain can only utilize ketones to a certain extent, and it requires approximately 30g of glucose daily to survive. ZC/V-VLC dieters typically stay in deep ketosis, thereby forcing their bodies to generate glucose via gluconeogenesis. In the absence of glucose, the human body activates a series of metabolic pathways that are in no way optimal or efficient from a thermodynamics perspective (the reconfiguration of amino acids to create glucose, for one, requires a substantial amount of energy). The livers and excretory systems of ZC/VLCers bear the burden of having to deal with the production of glucose from proteins (a non-optimal process), as well as shouldering the significant electrolyte changes that occur during deep ketosis, the latter of which evolutionarily may exist to simply facilitate the acquisition of glucose during difficult nutritional periods.
But what about the Inuit, whose consumption of a ZC/VLC diet has been stressed by advocates of deep ketosis constantly?
The Inuit, in those old days before the arrival of the European colonials, were able to thrive in the coldest parts of the north by making full use of their livers in the absence of glucose. In studies conducted in the 1930s, the Inuit were shown to consume large amounts of protein (250g+ per day) which exceeded their daily skeletomuscular requirements. Whether in ketosis or not (this has been a point of contention for some scholars), the large consumption of dietary protein kept the Inuit out of a fully ketogenic state, even though this metabolic reality came with an increased burden on their livers. Over the course of numerous generations and in response to the demands of a high level of protein consumption, the livers of the Inuits grew larger than those of most modern humans. Such an enlargement of the liver evidences the heightened level of stress on this particular organ due to a high protein diet. From an anatomically logical standpoint, the body will not aggrandize any component that it can use efficiently unless there is a need to augment its size in order to preserve homeostasis. In the case of the Inuit, elevated and prolonged states of gluconeogenesis made serious demands on livers, and this resulted in the general expansion of the organ. The Inuit express specific physical adaptations to a high protein, VLC/ZC diet that most followers do not possess. Even if a VLC/ZC subject consumes a low protein, high fat diet, this would still not represent an optimal metabolic state as per the basic principles which I have already discussed. The example of the Inuit is critical to emphasize because it represents the extent to which the ZC/VLC carnivorous diet is anti-optimal for most subjects; the Inuit were not in deep ketosis (in that their protein intake allowed for gluconeogenesis), and they certainly had larger livers to cope with the added metabolic stressors. One of the pitfalls of the ZC/VLC diet is that if a subject consumes too little protein, i.e., not enough to meet core daily skeletomuscular requirements, then it doesn’t matter if they eat large amounts of fat—the brain will demand its glucose, and it will pull the glucose from the very tissues of the body if it must.
Summaries and Conclusions: Making sense of the three dilemmas in concert
The first dilemma presented us with the disjointed evolution of the human body throughout the different historical moments that have led to the emergence of large and powerful brains. According to rigorous and respectable scientific studies, humans began as predominantly herbivorous mammals, and later acquired the desire to pursue predominantly animal proteins for subsistence. Beginning with the Middle Pleistocene, the brains of our ancestors increased in size substantially and swiftly, thereby reflecting the acquisition of carnivorous habits. This accelerated evolutionary increase in brain mass occurred over a period of several thousand years (documented by Ruff, Trinkaus et al. 1997), and likely was not accompanied by an accelerated evolution of the human microbiome. However, explicit symptoms of such a disjointed evolution did not emerge within ancient human populations because many of these groups consumed appreciable (30-100g+ carbohydrates) amounts of plant-based foods in addition to raw high-fat/meat/offal carnivorous diets (this is what I consider an optimal diet, for it keeps the body out of deep ketosis, in a fat-adapted state, and allows for the critically important microbiome/gut flora to subsist, and, indeed, thrive.) Alarmingly, though, within recent ZC/VLC experiments, evidence for disjointed evolution of the gut/brain systems is revealed by numerous symptoms which are both anecdotally and formally recorded. These symptoms include, for many dieters, the apparent overall reduction of bowel movements, which seems to reflect on the decrease of total bacterial biomass within otherwise healthy subjects. Purposefully limiting daily carbohydrate intake is an unheard of practice in extant and historical hunter-gatherer populations. The symptoms and evidence presented by the bodily problems of chronic ZC/VLC illuminates a particularly troubling—and at the same time scientifically fascinating—reality: while the human brain thrives on diets high in meats and fats (particularly raw meats and fats), the microbiome of our bodies does not fare particularly well under deep ketogenic/ZC/VLC conditions. Following arguments made in the second and third dilemmas, I feel that it is safe to conclude that deep ketogenic diets are not only anti-optimal for long-term subsistence (in regards to the efficiency and stress-levels placed on basic and emergency metabolic pathways, i.e., stress on the liver, kidney, etc.), but are also rather harmful to the overall health of the human subject (namely, by considerably altering the structures of a gut flora that evolved divergently in regards to other bodily organs such as the brain, and which remains nearly-exclusively dependent on nutrients derived from certain plant-based foods.)
