– Nutritional deficiencies, microbiome, organ stress, and more.
– What to actually expect on this diet
A Scapegoat Of Dieticians
As a diet that sits on a polar extreme of the nutritional extreme, carnivore is wide open to take body blows from dieticians. Both the type with degrees, and the ones who scream into the Twitter void. It’s the antithesis of the all-inclusive balanced diet, the well-established idea of taking everything in moderation. In that sense, carnivore has closer ties to the vegan template, they just happen to latch onto opposite ends of the dieting template.
And appropriately, many of the criticisms of carnivore aren’t much different to the ones lumped against the vegan diet. The complete avoidance of an entire biological kingdom, purportedly leads to deficiencies with noticeable side effects. But while that’s easy enough to put to the test, the allegations get more complicated from there. Ethical quandaries with eating meat, potential long-term trouble from certain compounds, and gross neglect of the gut. There’s a wealth of information, including studies, that would grace carnivore with hazard lights.
That being said, an imposing mountain of rubbish doesn’t make a safe place to stand on, it’s still made of junk. As for nutritional wisdom, it has continually shifted over the past half-century, and the metamorphosis won’t be stopping anytime soon. I’m not saying you should disregard the current consensus, but take it with a generous serving of salt. And if you’d rather not chase that salt down with water, there’s plenty of steak on offer here.
You need fiber to poop
Causes colon cancer
The tanking of the microbiome
Vitamin C deficiency
No phytochemicals
Excessive protein can shorten your life
Saturated fat clogs your arteries
Wrecks your kidneys
Lowers thyroid
Supporting global warming
1. You Need Fiber To Poop
Kicking off with the most important issue at hand, is the role of fiber in regulating bowel movements. Without nature’s special broom sweeping its way through the colon, waste gets stuck without an exit strategy, and constipation ensues. Except there’s no evidence to support this, while this study showed a no fiber diet resulting in reduced constipation, and zero bloating.
While it’s certainly true that fiber adds bulk to the stool, this doesn’t translate to effective bowel movements. The fact is, fiber is an extremely inefficient source of nutrition. We can only extract up to 4% of our energy needs from fiber. We gave up the right to digest cellulose, the most abundant compound in plants, four million years ago. All this means that when you treat yourself to a big bowl of salad, most of that is going to be coming out the other end.
This isn’t the way to fix a tender gut, it’s how you make things worse. The stomach and intestines are getting treated to undigested chunks of fiber, scratching and clawing their way through the entirety of the tract. At the very least, that’s a good case for a leaky gut.
Meanwhile, a carnivore diet should result in sensibly sized, regular bowel movements. At least once you allow for an adaptation period. Let’s just say the first few weeks can be a little too smooth.
The Verdict – More is not always better, and dropping fiber improves your pooping prowess.
2. Causes Colon Cancer
Fiber’s hallowed place as an essential nutrient leads to another drawback of carnivore, that being the potential for red meat to cause colorectal cancer. While the fiber broom works its magic by cleaning out the colon, red meat does the opposite. A paper from Oxford stated that eating red meat once a day increased the risk of colorectal cancer by a fifth.
The claim, however, is just yet another case of turning weak associations into explicit inferences. Epidemiological studies are considered weak science for good reason, there are far too many variables at play to turn correlating lines into actual evidence. Of which, there is none.
Meanwhile, there is a study, in rats, showing bacon having a protective effect against cancerous growth. This is backed up by another paper suggesting that red meat can be used to treat pre-existing tumours. At the very least, there’s nothing out there that should make you worry about carnivore’s effect on your colon.
The Verdict – There’s no actual evidence to support this one, as it’s only based on weak correlation.
3. The Tanking Of The Microbiome
We still haven’t shifted from miracle fiber, and in this case, we have it’s role as mother nature to your gut. Fiber is a prebiotic, meaning it acts as a fertilizer to your microbiota to expand and proliferate. It does this partly by supplying them with butyrate, the special fuel for the bacteria.
I’ve already played on the idea of us playing the role of hosts for the mitochondria, and I’m happy to use it again. Much like erythrocytes and mitochondria, the microbiota share a symbiotic relationship with human cells. We provide them with food that we lack the ability to absorb, they break it down into valuable compounds like B12 and biotin. The microbiota also have outsized effects on mood and motivation. They’re a critical juncture in metabolism, and there’s no disputing that.
So what happens if you take away their meal ticket by refusing to ingest fiber? As a ketogenic diet, carnivore boosts the production of Betahydroxy-Butyrate (BHB), a primary ketone. BHB, as you may have noticed, has the gut fuel ‘butyrate’ included in its name. It can work perfectly well as a way to keep the lights on in the microbiome. Possibly better, if you consider the fact that BHB can be produced from an unquenchable source, your fat stores. That’s sustainable gut agriculture.
There is the question of gut diversity, where different foods supply different species of bacteria. A point where you’d imagine carnivore would take a hit, because you’d have to go hard on wild game to ensure food diversity.
However, there’s no evidence to say that greater gut diversity leads to better health outcomes. There is a paper suggesting that it might be the opposite. Considering that rampant gut bacteria can lead to dysbiosis, and that carnivorous animals display low diversity, there’s a good case to be made that we shouldn’t be trying to create a Garden of Eden in our intestines.
The Verdict – Fiber can be easily replaced by BHB to fuel the gut, which is abundant on carnivore.
4. Gives You Scurvy
The first and most obvious micronutrient deficiency that’s attached to carnivore, is Vitamin C. The lack of this vitamin leads directly to scurvy, as many long-haul sailors have found out over recent centuries. At its most pronounced, it spells out death, but you can encounter less severe symptoms like swollen gums and easy bruising. And despite being a classic vice of the Age of Exploration, scurvy still strikes today. In 2016, 128 people in England were admitted to hospital with the condition. On the bright side, at least we know how to treat it now.
Vitamin C has its other uses, but its prevention of scurvy is a real highlight. Meat is often referred to as having zero of this special vitamin. However, completely untrue. Fresh beef contains 2.5mg per 100 gram serving. Now that’s not necessarily quite enough to get you to your 40mg requirement. Beef liver has 25mg per 100 grams, which should cover your bases when added to your steak tally.
That being said, it might look you’re just scraping by. The 40mg recommendation is designed to prevent bad things from happening, rather than fuelling optimal health. This is where we need to bring up the fact that Vitamin C plays a big role in glucose metabolism. A resource-sapping task that you’ve now taken out of its hands. There aren’t any RDAs designed with carnivore in mind, but if they were, Vitamin C would be markedly lower. Certainly, there’s plenty of evidence of people getting by perfectly fine without getting their five a day. Sailors would struggle with dried meat, which drains nutrients, but show no symptoms with fresh meat.
The only plants Inuits eat are the occasional smush they find sewn up in a Caribou’s stomach. When Vilhjalmur Stefansson lived amongst the tribes for a year, he took particular note of their perfect health. His book is one I’d thoroughly recommend for anyone delving into meat-based living, and you check it out in my recommended reading list.
The Verdict – You need less Vitamin C on a carnivore diet, due to resources not being used for glucose metabolism. Fresh beef itself contains enough of it, especially when you throw liver into the mix.
5. No Phytochemicals
Here’s why dieticians tell you to eat the rainbow. Phytochemicals are non-nutritive compounds that have purported health benefits. Isoflavones, curcumin, isothiocyanates, and resveratrol are a few popular examples. The benefits include longevity, hormone support, and reduced inflammation. The catch is right there in the name, phytochemicals are a plant exclusive. So a carnivore diet cuts you off from a wide range of miracle compounds.
The hype around phytochemicals is based much on the concept of plants with noble intentions. The idea that plants only have your best interests in mind, that they are specially equipped to heal and invigorate the human species. This flies in the face of a fact of nature, you have to be selfish in order to survive. If you’re a stalk of wheat or broccoli, being eaten is rarely in your best interests.
The Hidden Dangers Of Plant Toxins
Then there’s the whole trouble with our biology being specialised for digesting and absorbing meat, rather than plants. Phytochemicals can possibly have medicinal uses, but they can’t be held up as panaceas. Certainly, there is evidence of unwanted side effects in humans.
Isoflavones, found in soy products, is a phytoestrogen, meaning it latches onto estrogen receptors and emits a weaker signal. It’s a hormone disruptor, and it’s specifically designed by the plant to disable the reproductive function of predators. Even resveratrol, a hallowed supplement for fighting the flames of ageing, can actually increase oxidative damage in some circumstances, Resveratrol is also a phytoestrogen, and therefore shares the capacity for throwing your hormones into disarray.
Those are just a few examples of phytochemicals that warrant some skepticism. And to round it off, grass-fed meat and milk contain plenty of these supposed plant-exclusives. Such as terpenoids, phenols, carotenoids, and antioxidants. That’s the magic of ruminants, digesting plant matter and enabling us to get bioavailable plant nutrition. Personally, if I were to try out phytochemicals, I’d rather get them without all the toxins and indigestible fiber.
Why Ruminants Are The Pick Of The Food Chain
The Verdict – Grass-fed beef and dairy do actually contain phytonutrients, even on the level found in plant foods.
6. Excessive Protein Can Shorten Your Life
We’re going to tackle the kidneys just yet, this one is slightly more complicated. Protein has caught some stick in recent years for its prodding of the anabolic switch. MTOR is a pathway associated with growth. It enables cells to replicate and increase. When you’re busting bicep curls five days a week, you might see MTOR in a positive light, but it’s often portrayed as a carcinogen when taken to an excessive degree. In fact, many cancer treatment drugs are MTOR inhibitors.
In the name of preventative treatment, several diets recommend you take the minimal amount of protein needed to support muscle turnover. In the case of the Fasting Mimicking Diet, it’s virtually non-existent.
However, the causal link between protein and mortality is extremely tenuous at best. It could well be another case of taking a real problem but drawing the line at an arbitrary point. MTOR can result in cancerous growth, but it also enables you to build and repair natural tissues, like muscle. So it’s complete overkill to go ahead and label the anabolic switch as the grim reaper.
A carnivore diet does activate MTOR through the amino acid, leucine. But insulin turns it on to a much greater degree, with the effect lasting three times as long. Insulin is still a feature in a zero carb affair, but it’s suppressed throughout by the counterregulatory actions of glucagon.
And then there’s the small matter of protein’s critical role in preventing muscle breakdown, which becomes more and more important as you age. The idea that a macronutrient that was a centerpiece of the evolutionary diet, sends you to an early grave, is fanciful.
It’s certainly true that we shouldn’t overstimulate MTOR, which is why I’ve always preached about balancing out cycles of feasting with fasting. That’s something that carnivore is highly compatible with, since it doesn’t spike blood sugar and is extremely satiating. So the answer to the MTOR problem is already written into the diet.
The Verdict – If anything, reducing carbs would be the best way to tackle the supposed problem of MTOR.
7. Saturated Fat Clogs Your Arteries
Cholesterol is a minefield of a subject to navigate, having been implicated as the driver of heart disease, the leading cause of death in the UK. And yet, it also happens to be a critical compound that forms the precursor to the likes of testosterone and cortisol. Either way, saturated fat has ended up being the scapegoat, due to its effect on raising LDL cholesterol, the piece that acts as the big bad to your arteries.
Despite most governing bodies taking that association and running with it, there hasn’t been any concrete evidence linking saturated fat to heart disease. Association doesn’t mean causation. But beyond the absence of guilt, there are several good reasons why saturated fat should be redeemed.
- There are studies showing high cholesterol-reducing mortality. Thankfully, many are starting to move on from blaming total cholesterol.
- LDL particles themselves don’t cause arterial plaques. But when they get oxidised and glycation, they certainly do. Saturated fat is highly resistant to oxidation, and is obviously not a sugar. Whereas processed foods contain the deadly combo of seed oils and sugar. Oxidation, glycation.
- Saturated fat also increases HDL, a trait it shares with exercise. HDL is regarded as a healthy form of cholesterol, because it acts as the cleanup crew.
- Calling LDL ‘bad’ is a gross oversimplification. There are two types of LDL. One is small and dense, the other is big and fluffy. The latter is harmless, while the former can get wedged into tight spaces. Potentially leading to plaque. Well, that could change the whole outlook on cholesterol, because VLDL is increased by insulin resistance. Not the type of fat.
But hey, on such a complicated topic, you’re best off doing your research rather than taking on the gospels of diet gurus.
The Verdict – Beyond vague correlations in epidemiological studies, there’s nothing to link saturated fat with heart disease. And there’s plenty of reasons to worry about seed oils instead.
For more detail, check out my article on saturated fat.
Why Saturated Fat Is The Critical Ingredient
8. Wrecks Your Kidneys
Besides its MTOR affiliation, a high protein count has also been associated with impaired kidney function, even kidney stones. Much of that association is due to the fact that when the kidneys get damaged, one of the first signs is protein leaking out in the urine.
This is a classic myth that has done the rounds for decades, fanning worry over the implications of a high protein diet. But despite having a potential mechanism, there doesn’t appear to be evidence of the crime. At least not in healthy kidneys. Pre-existing conditions can certainly hurt your ability to efficiently filtrate amino acids, but that’s a special case.
A 2005 review of existing data, stated that “while protein restriction may be appropriate for treatment of existing kidney disease, we find no significant evidence for a detrimental effect of high protein intakes on kidney function in healthy persons.”
So it certainly seems the case that slamming down the protein won’t put you on the fast track for organ failure. It once again stands to reason, that the body is perfectly capable of dealing with high amounts of an evolutionary food source. Cavemen didn’t drop dead from eating too much mammoth steak.
The Verdict – While pre-existing kidney disease certainly calls for protein restriction, there’s nothing wrong with sending high protein to a healthy set of kidneys.
9. Lowers Thyroid
Among the many adaptations to a ketogenic diet, is a decrease in T3. Since it’s the compound that powers the metabolic rate, having low T3 might worry those who understandably want great energy and fast fat loss. A drop in metabolic rate typically brings lethargy, insomnia, and weight gain. The phenomenon of ketosis lowering T3, has been used to argue that a low carb diet throws the switch towards ‘starvation mode’. In other words, hypothyroidism. Making it potentially workable over a few weeks, but utterly unsustainable over the long term.
But when you compare the effects of ketosis to hypothyroidism, a significant difference stands out. T3 is made from T4, its inactive form. In the case of hypothyroidism, T3 is decreased, while T4 ramps up. That shows the body is responding to the lack of T3 by increasing T4. In a ketogenic diet, while T3 goes down, T4 stays the same. The body wasn’t in crisis management. It had already adapted to meet the new demands.
The trick that prevents ketosis from crippling the metabolism, is an increased sensitivity to T3. Meaning the body requires less to do the same job. There’s no evidence to point to ketosis meaningfully lowering the metabolic rate. It’s an entirely different fuel system to glucose, and as such, the markers are changed.
There’s a potential case to be made for intermittently spiking the system with low toxicity carbs, as that can raise leptin, which in turn can boost T3 numbers. But that’s merely hypothetical, so carb cycling should be kept in the experimental category.
The Verdict – T3 does decrease during ketosis, but the body’s sensitivity to T3 also improves. So the effect on the thyroid could even be a net positive if you’re going in with hypothyroidism.
10. Supports Global Warming
Finally, we have the big fish, the trump card that the plant-based folk can always summon when nutritional dogma doesn’t do the job. Climate change is real enough, and the role of livestock has been continually brought up as one of the major perpetrators. They are causing droughts, releasing toxic fumes into the atmosphere, and taking up valuable land that could otherwise be used for sustainable and economic crops.
All of these claims are made from deeply flawed data, and I’ll touch on a few major ones.
There’s an infographic doing the rounds from Meatless Monday, that states that a ¼ pound burger needs 10 bathtubs of water. But even in the case of grain-fed beef, 94% of that water is rainfall.
What would happen if you removed the cow from the equation? That rain still hits the ground. We’re not talking about diverting water or drawing it up from wells. Agriculture takes care of that, by taking up 70% of the world’s fresh and ground water.
The next claim is from the FAO on GHG emissions, where the global livestock sector is said to produce more greenhouse gas the entire transport sector. The main culprit is methane, which is belched rather than farted by cattle. The carbon equation neglects to account for methane’s short life cycle, where it’s broken down after ten years.
Also ignored is the ability of cattle to sequester carbon in the soil. When raised in regenerative pastures, they are a net negative on carbon emissions.
To compound the FAO data, it also considered the entire cradle-to-grave path of meat production, while neglecting to do the same with transport. When comparing direct emissions from livestock and transport, it’s 5% against 14%.
As for the idea that the world would be best served converting grazing lands towards making more vegetables, that’s not getting us anywhere. 70% of current agricultural land is suitable for livestock and wild animals, not for producing crops. A plant-based vision simply isn’t tenable with the landscape.
In short, the allegations weighed against livestock simply don’t survive under scrutiny. Ruminants in particular have played a central cog in the ecosystem over the entire scope of our existence as a species. The notion that they could be the ones burning it all down, is ridiculous. Whereas the proposed alternatives have only existed since the agricultural revolution, 10,000 years ago.
The Verdict – The myth of cows causing global warming is the result of flawed data weaved into flashy infographics. But let’s talk about how much water it takes to produce a pound of almonds.
Wrapping Up
Carnivore was quite likely the dominant diet of our paleolithic ancestors, over a period of several million years that covered the vast majority of our species’ existence. Red meat was inarguably the key feature of the dinner menu, seeing as how we virtually wiped the megafauna off the map in the hunt for steak. That fact of affairs doesn’t gel at all with the modern idea that meat is bad for you. Specialised biological adaptations don’t unravel over 10,000 years because humans began to consume more plants.
We were meat-eaters, we’re still meat-eaters, and carnivore is probably the safest diet out there. The research itself doesn’t disagree with this. You can find plenty of data on the insidious effects of seed oils and sugar, but red meat itself doesn’t have anything going against it besides weak correlations. Until that changes, there’s no reason to think a carnivore diet comes with adverse health outcomes.
