What you’re getting yourself into
I’m addressing each of the alleged dangers of a carnivore diet in one colossal list. So get strapped in.
As an extreme diet that sits on the fringes of the nutritional spectrum, and one that has seemingly sprung out of the obscured shadows of internet forums, carnivore has its fair share of critics.
It collects virtually every negative word that’s been waged against meat consumption, alongside the vitriol of people who insist that getting your fruits and veggies in is the key to optimal health.
When you put those two together, you get an incredibly long list. So rather than constantly have to rebuke these dangers on my socials, I decided I’d bring them all together into one colossal article.
So whether you’re worried about some alleged side effect of carnivore, or you’re simply looking for ammunition in the next dinner debate, this will act as your base of operations.
1. Scurvy
For 17th and 18th Century sailors embarking on perilous long voyages across the oceans, their largest fear didn’t come from the sighting of a skull and crossbones flickering from the mast of a ship emerging on the horizon.
It was the diseases that plagued them along the way, preying on cramped sailors surviving on the thinnest of rations.
Scurvy was the biggest, the deadliest, and is still the most notorious.
A “luxuriancy of funguous flesh… putrid gums and… the most dreadful terrors”, as described by the commander of a British expedition that lost 1,300 of their 2,000 men.
The diet of these sailors was a delicious ensemble of hard biscuits and dried meat.
Eventually in the 1790s, it was discovered that citrus fruit could be an effective treatment for scurvy. In the 20th century, Vitamin C was isolated, and scientists determined that cooked meat contained minimal levels of this nutrient, well below the requirements. Naturally it was just rounded down to zero, and the belief that meat didn’t contain Vitamin C stuck.
But this belief has been contested and rejected for as long as it has existed.
“When first thrown wholly upon a diet of reindeer meat, I was inclined to believe that scurvy might result from the absence of vegetable food. But I was gratified to find that not a single case occurred.”
– Frederick Shwatka, on the Inuits, 1880.
During James Clarke Ross’s Antarctic voyage in 1839, scurvy broke out, but men who were able to hunt and eat fresh penguin or seal meat improved quickly.
People who didn’t eat vegetables or fruits, didn’t get scurvy. Those who got scurvy, cured it by eating fresh meat.
This invalidates the entire hypothesis of meat causing scurvy, but let me explain why.
When meat isn’t dried out, it will contain more than enough Vitamin C. Beef has about 25 ug of Vitamin C per gram of beef. So if you eat 2 pounds of fresh beef, you would get about 18 mg of Vitamin C. Even accepting that you’ll lose some of that through cooking, you’ll still be able to sneak past the scurvy monster.
Vitamin C is outcompeted by glucose, which drastically raises its requirements on a carb-based diet. The requirements are what we see in the RDI values. A carnivore diet would therefore need a fraction of that Vitamin C needs.
But there’s a second factor to consider, which is Vitamin C’s role as an antioxidant. Without the usual avalanche of sugar, seed oils, plant toxins, and pesticides, your endogenous antioxidants aren’t going to be working overtime to quell the free radical storm.
These antioxidants are glutathione and uric acid, and they will be produced at higher levels on carnivore thanks to all that meat providing an abundant supply of the necessary building blocks.
Verdict
In a high carb diet, you need Vitamin C in the milligrams.
On carnivore, you only need it in the nanograms.
This illustrates a key point that will raise its head frequently in this article. Carnivore shouldn’t be held hostage by the demands of the RDIs that were designed specifically for high carb diets. The landscape is different, the markers are different, and the requirements should be different.
I’m not going to get bogged down addressing every alleged deficiency in a carnivore diet, since I’ve already written an article doing just that. You can check it out here.
2. Clogged Arteries
I’ve lost count of the amount of times I’ve been told to enjoy dying within the next ten years with clogged arteries. I suppose that’s one way to realign the reality that’s just been thrown in disarray by someone seemingly thriving without a single fruit or vegetable.
I might be thriving now, but just wait till the vultures come home to roost.
In all fairness, this is the most popular amongst carnivore’s murderous ensemble. It’s dictated sixty-odd years of global dietary policy. It birthed a trillion dollar statin industry. It’s the pearl of common wisdom behind the divide between good fats and bad fats.
There is plenty of weight to it. But that doesn’t make it credible, it just makes it noisy.
As much as it might appear intuitive that lard congealing in a drain pipe will do the same thing to your arteries, it masks the fact that if your blood vessels were cold enough for that lard to congeal, you’d have much more pressing issues to deal with.
But it’s not just a case of flawed logic. Saturated fat has been repeatedly shown to be benign for heart health when it’s included in the context of a healthy diet. Because all the studies that show some elevated atherosclerotic risk with red meat consumption, happen to fall victim to the healthy user bias.
This is another persistent and fatal flaw in carnivore’s dangers. People believe red meat is unhealthy. That means that a larger portion of people that eat red meat will be ambivalent about their health and longevity. They’ll be less likely to exercise, more likely to drink and smoke, more likely to be hugging the poverty line. Such people will be invariably unhealthy when compared to those who do their due diligence, restrict red meat, and get their fruits and veggies in.
The blame for their ill-health, and the credit for metabolic-supremacy, cannot be put at the foot of excess red meat or indulgence in rainbow plants. There are simply too many confounders.
Beyond the healthy-user bias, the mechanistic explanations of how saturated fat causes heart disease is also a bust. LDL can be expected to go up on a carnivore diet, because LDL is a lipid carrier in a diet that’s high in fat. LDL is associated with elevated atherosclerotic risk, but ketosis increases the large LDL particles, which are benign. It reduces the small dense LDL particles, which are atherogenic, because they are easily oxidised.
Without LDL being subjected to oxidation, and thereby becoming a problematic compound that white blood cells have to scavenge, the process of atherosclerosis cannot happen. The risk of LDL being oxidised is raised by increasing the production of small LDL particles, lining the LDL particles with fragile linoleic acid, and inflicting oxidative stress on the body.
These risk factors are raised by a diet high in sugar and seed oils, with particular weight on the latter, since they are exceptionally high in linoleic acid.
Verdict
To keep things simple, carnivore can raise LDL, but that doesn’t mean elevated heart risk without a rise in small dense LDL particles and rampant oxidative stress. Both of which are quelled on a carnivore diet that’s bereft of sugar, seed oils, pesticides, and plant toxins.
The ineptness of high LDL as a risk factor is reflected in the recent study on metabolically healthy people with exceptionally high LDL counts who followed a ketogenic diet over a year while exhibiting no plaque progression.
Meanwhile, heart disease was exceptionally rare until seed oils entered the food supply. Despite red meat getting a 2.4 million year head start. The notion of blaming modern diseases on ancient foods is just profoundly nonsensical.
3. Diabetes
It might seem curious how a disease of glucose intolerance can be caused by a diet that omits glucose. But I’m willing to steelman the reasons of whatever researchers put together gems like the study that stated “Red meat raises diabetes risk by 62%”.
Red meat contains high levels of saturated fat, which apparently isn’t just a threat to your drain pipes. It also raises insulin resistance, and insulin resistance defines the state of diabetes.
A ketogenic diet in and of itself will raise insulin resistance, which you may recall is a diabetic problem. But in both of these cases, I would also posit the fact that insulin resistance isn’t a glitch in the system. It’s there for a reason, and it doesn’t always signal disaster. It can be a perfectly serviceable part of a thriving system.
That’s where we should distinguish between physiological and pathological insulin resistance. The former is a function of the body optimising energy metabolism. The latter is a compensatory and defensive adaptation to mitochondrial dysfunction and impaired energy metabolism.
Saturated fat raises insulin resistance in the fat cells, which acts as a localised signal to block the incoming fats from being stored, and for it to be burnt as fuel instead. Some of it even gets wasted as heat through reverse electron transport, hence the meat sweats people get after a heavily fattened pile of steak. This insulin resistance is inherently a signal of high energy availability.
A ketogenic state raises insulin resistance in the peripheral tissues, like the muscles, in order to spare glucose for the few tissues that actually need it, like the erythrocytes. Needs that can be easily met by gluconeogenesis. This insulin resistance is a transient state that easily reverses after a few carb-laden meals.
Meanwhile, there are plenty of studies showing that a ketogenic diet improve insulin sensitivity, by means that extend beyond weight loss and carbohydrate restriction.
Ketosis actively improves mitochondrial function by increasing their number (mitobiogenesis), defences (mitohormesis), and quelling free radical damage. Given that insulin resistance is a problem of mitochondrial dysfunction at its heart, it makes intuitive sense that a diet that promotes ketosis would be a boon for alleviating pathological insulin resistance.
As for the endless conveyor belt of epidemiological studies that show red meat elevating risk of chronic disease, it’s pure data manipulation and misleading statistics. I’ve already covered the healthy user bias, but there is another gigantic red flag that needs to be given its due.
The quoted percentages in the study’s headline will always be relative risk rather than absolute risk.
Let’s say a study observes 100 people who eat very little red meat, and another 100 who eat it regularly.
5 out of the first group, and 6 out of the second, end up getting diabetes over a lifetime.
The absolute risk of eating red meat is therefore an increase of 1%. The relative risk is 20%.
I don’t know about you, but I wouldn’t be willing to give up on the most delicious and nutritious food on the planet for the sake of a 1% reduction based on flaky data.
Verdict
So the consensus with carnivore and diabetes is the same as the one with heart disease. It’s not just innocent. It actively lowers your chances.
4. Colon Cancer
The carnivore colon is the last of the four horsemen of the ancestral apocalypse. And just like the state of affairs with diabetes, the alleged risk breaks off into two parties. The abundance of red meat, which has been the driving force behind all forms of chronic disease, finally getting there after 2.4 million years of mixed results. And by mixed, I mean providing humanity with all the build blocks it needed to become the apex species of the planet. But it got there in the end, and now it’s finally wreaking havoc.
If nothing else, it’s an inspirational tale that we can all make it one day. Even if we initially fail for 99.99% of the evolutionary timeline.
Red meat contains high levels of iron, which can lead to the formation of genotoxic compounds that can mutate DNA. High temperature cooking can also produce its own set of carcinogenic compounds.
This is how we end up with articles like “A rasher of bacon a day ‘ups cancer risk’ from the ever-reliable BBC. At the same time, there have been plenty of studies over the years that failed to show an association between red meat and cancer. Even the carcinogenic compounds that can rise from high heat cooking haven’t been shown to have a raised risk.
One major review of 73 studies found that “The possible absolute effects of red and processed meat consumption on cancer mortality and incidence are very small, and the certainty of evidence is low to very low”. A 2018 study showed no difference in colon cancer rates between meat-eaters and vegetarians.
So as badly as some groups have tried to label red meat or processed meat as a carcinogen, the data has never been incriminating.
But let’s look closer at one of the compounds in red meat that is said to be carcinogenic. There are rat studies showing that heme iron is only carcinogenic when combined with seed oils. In this one, olive oil actually had a preventative effect. But sunflower oil was a disaster.
So which would you imagine is the carcinogen? The compound that has been in abundant supply in our diet over 2.4 million years, or the rancid factory fat that is known to be highly susceptible to lipid peroxidation, and becomes part of the lining of your cell membranes, making them highly vulnerable to damage and mutation?
Nitrates are always brought up as carcinogenic baggage that come with processed meats like bacon, but they only account for 5% of the nitrates in the diet. Vegetables make up 85%.
Meanwhile, nitrates are used to make nitric oxide, which does various beneficial stuff like dilating blood vessels, lowering blood pressure, and protecting against infections. So it’s a stretch to see it as inherently harmful.
When the ‘successful’ processed red meat studies champion 20% increases in cancer risk, but actually produce a 0.1% increase in absolute risk, you should be a little skeptical.
The second issue is the lack of fiber, which as everyone knows is nature’s broom and is needed by our body to sweep things out of the gut and prevent meat chunks from building up and causing cancer.
But the thing with fiber, is that its merits are entirely based on weak epidemiological links, and its effect on colon cancer is tenuous at best. Undigested foods lingering in the intestinal tract can weaken colon cells and promote cancerous growth, and there’s no bigger culprit here than fiber, which is inherently indigestible.
The short chain fatty acids produced from fiber do help protect against cancer, but that’s not a fiber special. Dairy, ketones, and collagen can all be used to make butyrate, they’ll just be able to accomplish that without the baggage of dragging abrasive sawdust through the narrow passage of your large intestine.
Verdict
The link between red meat intake of any kind and colon cancer is completely insignificant. Whereas there is a very good argument to be made with seed oils. Fiber, meanwhile, is a digestive liability that doesn’t deliver on the many promises it makes.
Surprisingly, a cancered colon is not an issue worth losing sleep over when you follow a diet that preceded the explosion in chronic disease.
5. Constipation
Speaking of fiber’s failed promises, we have another classic in the form of constipation. A high-fiber diet is held up as the undisputed king of effortless digestion and regular hassle-free poops. This only makes sense as long as you don’t think about it for longer than five seconds.
Imagine if you tried to fix the traffic congestion on the motorway by funneling in more cars. But that’s the essence of fiber’s fix for constipation. You’re attempting to fix an issue of a clogged colon by adding more indigestible bulk. When you could just try not causing the issue in the first place by eating foods that get digested well before they reach the colon.
Meat is the ultimate low-residue food, which means around 1-5% of the total weight of the meat is left behind in fecal matter. The idea that such an insignificant amount of leftover bulk could cause constipation is laughable.
Compare that 1-5% number with the residue in plant foods.
- Leafy Greens (e.g., kale) 30–50%
- Whole Grains (e.g., oats) 10–30%
- Legumes (e.g., beans) 15–25%
- Root Veggies (e.g., carrots) 10–20%
- Fruits (with skin, e.g., apples) 10–30%
That’s how we end up with a study showing that a zero fiber diet cures constipation.
Verdict
Carnivore doesn’t cause constipation. It cures it. Because constipation is caused by eating too much indigestible food, while meat is highly digestible and very little survives the intestinal tract.
6. TMAO
Trimethylamine N-oxide is another ‘possibly carcinogenic’ compound that’s been linked with cancer. It’s a breakdown product from choline, which is found in red meat and eggs, amongst many other foods. But it’s the steak and eggs that’s the problem.
What doesn’t get mentioned in the vilification of TMAO, is that fish contains 50 times more TMAO than beef. Except fish has never been labelled a carcinogen. Everyone loves fish. Even the vegetarians, hence why they decided to consider it ‘not really meat’ and open up the door for pescetarianism.
This already grants the TMAO a quick and merciful death, but while we’re here, a study found that there was no link between choline intake and heart disease. TMAO itself has yet to be shown to be harmful, beyond spurious correlations. So it’s another nothing burger that the fake meat industry did their best to turn into a successful hit piece.
Verdict
Meat and eggs raise TMAO, but fish increases it seismically more, with none of the consequences. This shouldn’t stop you from chasing higher levels of choline, given that it’s a bastion of healthy cognitive function.
7. Inflammation
A diet that’s heavy on meat and saturated fat is often thought to promote a pro-inflammatory environment, which goes right in line with the central principle of modern nutrition, that our oldest food is the culprit behind all the modern diseases.
Systemic inflammation is the breeding ground of chronic disease. A carnivore diet has been hypothesised to cultivate such an environment through a few different mechanisms.
Saturated fat has been linked with increasing the inflammatory markers CRP and TNF-alpha. But this association hasn’t held up with any consistency, as evidenced by this study showing no link between saturated fat and inflammation. It’s another connection that’s tenuous at best.
The elevation of inflammatory marks isn’t in and of itself a bad thing. It can be a transient, controlled mechanism that signals for the release of energy substrates and repair. Exercise elevated inflammatory markers in the short term.
It’s the pathological, sustained elevation of inflammatory markers that spells danger, and there is no link to back that up. Furthermore, carnivore is a ketogenic state, and ketones have specific anti-inflammatory and anti-oxidative effects across the system. Then there’s the sheer drop in inflammatory baggage that would normally come in the form of plant toxins, sugar, and pesticides.
Finally, there’s the ratio of Omega 3:6, which is a key marker of the inflammatory state of the body. Omega 6 literally breaks down into pro-inflammatory compounds in the form of prostaglandins.
The ancestral equivalent was 1:1, in the modern diet it’s closer to 1:20. A carnivore diet that’s based on grass-fed red meat is the undisputed king of remedying that skewed ratio, since the majority of Omega 6 comes from plant oils, seeds, nuts, legumes, grains, and monogastric animals.
Verdict
Saturated fat might raise inflammatory markers in the short term, but it’s a transient and controlled mechanism that does not lead to chronically elevated levels. Carnivore is itself inherently an anti-inflammatory diet thanks to the lack of sugar, seed oils, plant toxins, and pesticides, alongside the targeted anti-inflammatory effects of ketones.
8. Cooking Meat Releases Toxic AGEs
High-heat cooking releases advanced glycation end-products, which cause inflammation and oxidative stress. But while it is a potential reason to avoid charring your meat, there is one primary speedbump when wielding this against meat-eaters. This is a consequence of foods containing glucose. Meat contains very little glucose. You’re going to get a whole lot more AGEs when using foods that contain high amounts of glucose.
AGEs in a burger would be more the fault of the buns than the meat patty that’s snuck in the middle. But even then, dietary AGEs are broken down in the stomach, and glycated amino acids will most likely not be absorbed through the gut lining, as transport channels work by shape configuration.
But you know what will get past the stomach lining? The ones that don’t have to. As in the glucose that’s produced endogenously during hyperinsulinemia and high blood sugar. These are the ones that inflict direct damage on proteins that are already in the body, like causing wrinkles in the skin by binding to collagen.
Verdict
High-heat cooking can cause AGEs to form, but dietary AGEs are not the problem. AGEs produced through high blood sugar episodes are the real culprits, and that’s a fault of metabolic dysfunction, not a bit of carrying on your grilled tomahawk.
9. Too Acidic
Meat is acidic, which could lead to chronic low-grade metabolic acidosis, a prime promoter of inflammation and disease. Plants on the other hand, are alkaline, which is deemed to be protective, cue the whole alkaline water-chugging fad we went through a few years back.
This can be seen as the “meat kills, plants kill” world-view in a microcosm. A carnivore diet that’s heavy on meat and stripped of alkaline plants will melt you from the inside.
But now comes the confounding nuance. So let me rattle a few off.
1. Adding bicarbonates from plants doesn’t necessarily make the blood less acidic.
2. In a ketogenic state, adding bicarbonates increases ketone levels to compensate.
3. The detoxification of plant secondary metabolites requires acid production.
4. Blood pH is tightly regulated with very little room for maneuver, regardless of what someone eats.
It’s almost like ketosis is a different metabolic state with different markers that define a healthy equilibrium.
Verdict
Plants don’t inherently make the body less acidic, carnivore doesn’t inherently make the body more acidic, and the body is more than capable of keeping pH stable regardless of what you’re eating. Because deviating by a few decimal points would literally render you dead.
10. Gout
In medieval Europe, gout was called the “disease of kings”, because only the wealthy were able to afford the foods that were thought to cause it: meat, seafood, and alcohol. Meat itself was seen as a food of indulgence and gluttony, and was thought to heat the blood, leading to inflammation and gout.
So gout became symbolic of the divide of societal classes, and meat was marked as one of the chief perpetrators of the disease. In the 20th century, it was discovered that the purines in meat break down into uric acid, which is elevated in gout. and a plausible mechanism was put together.
Uric acid gets a terrible rap thanks to this connection, which is doing it a disservice since it acts as a potent antioxidant in the body. So it’s not inherently problematic. Gout is highly correlated with metabolic syndrome, meaning the best way to alleviate it is to fix the insulin resistance that underlies such symptoms. As a ketogenic diet, carnivore is ridiculously potent at fixing the markers of metabolic syndrome.
But let’s say you already suffer from gout. Are the purines in meat a problem?
There’s the small fact that fructose and alcohol both increase uric acid significantly faster and more dramatically than purines. They raise uric acid within a matter of minutes of ingestion, while purines are a breakdown product that take a while to manifest.
Beef also happens to be low in purines when compared against foods like sardines and liver. So if you were in a state where the body was vulnerable enough to feel the effects of purines, you wouldn’t have to worry about muscle meat. Fish and organs would be the primary culprits within the carnivore kingdom.
Verdict
If you’re metabolically healthy, you don’t have to worry about gout. But if you’re metabolically dysfunctional, then a carnivore diet cuts out the two likeliest culprits behind gout flare ups, in fructose and alcohol. But you may need to also minimise fish and organs to be completely symptom free.
11. Kidney Disease
The threat to the kidneys has been one of the enduring fears of a high protein diet. The idea is that excess protein leads to the kidneys having to work harder to get rid of the waste, leading to damage and ultimately chronic kidney disease.
However, high protein intakes have been associated with lower risk of kidney disease, which puts a damper on the whole scare. The only danger high protein can pose, is going to be against people that already have significantly damaged kidneys.
Besides, carnivore is designed to be high fat, rather than high protein. At least 70% of your calories should be coming from fat, which further negates the problem.
Verdict
Carnivore is high fat, not high protein, which isn’t an issue regardless assuming you haven’t already exacted significant damage on your kidneys.
12. Kidney Stones
Much like the case of gout, the existence of purines in meat, which can break down into uric acid crystals, is used as a plausible mechanism for how carnivore can lead to kidney stones.
This ignores the fact that oxalates cause 80% of all kidney stones, and that the purines in muscle meat is a very minor player in uric acid crystal formation. The big ones are sugar and alcohol, with organ meats and shellfish being some distance behind.
Verdict
Carnivore does not cause kidney stones, and if you want to avoid dealing with that pain down the line, just don’t eat spinach. As well as every other plant superfood, alcohol, and sugar.
13. Low Testosterone
While I haven’t encountered issues with symptoms of low testosterone across my five years of carnivore, it is a point of concern for people that like to get down and dirty with their biomarkers. This would be the case of a ketogenic diet raising sex hormone binding globulin, which as its name suggests, lowers free testosterone in the blood by binding to it.
On one hand, research like this 12 week study on resistance-trained men shows a ketogenic diet can improve total testosterone levels and body mass. Considering that cholesterol is the necessary precursor to testosterone, and that nutrients like zinc are needed for testosterone production, it makes sense that a diet high in fatty animal foods would be a force for elevating total testosterone levels.
Meanwhile you have the state of pathological insulin resistance that carnivore alleviates. Insulin resistance increases visceral fat accumulation, which in turn spikes aromatase activity, converting more testosterone to estrogen. It also blunts nitric oxide production, reducing testicular perfusion, and thereby lowering testosterone production.
But then you have studies showing free testosterone getting dropped in a ketogenic diet, even if it might just be in the short term. What gives? I have had a few concerns with SHBG in the past, and trialled boron supplements as a way to lower SHBG. But after looking deeper into the subject, I decided I could continue pumping iron without my boron insurance policy.
The thing with SHBG, is that it’s not simply a lock that’s placed on your testosterone, thereby shutting them out of the game. SHBG is a multifunctional player that can latch onto different receptors and orchestrate steroid action to a far greater degree than previously thought. SHBG is also increased by lifting weights, and is correlated with increased strength and hypertrophy.
Personally, I haven’t tested my free testosterone, or any other marker for that matter. I don’t believe in testing when there are no pathological symptoms that would imply there’s something wrong under the hood. I haven’t had any issues stacking muscle on this diet. So I haven’t felt the need to test.
Verdict
A carnivore diet may lower free testosterone by raising SHBG, but that doesn’t inherently mean that you’ve got less testosterone to build strength and muscle. Because SHBG is by itself capable of testosterone action.
14. Brain Fog
“The brain needs a 120 grams of carbs a day”
The brain does need 120 grams of glucose a day, when you’re eating a high carb diet. The act of cutting out carbs can often lead to issues like headaches and brain fog as the body scrambles to find ways to fuel its main energy hog. This has led people to infer that the brain operates best on carbs, and that a zero carb diet would be a serious drag on whatever cognitive prowess they can put together.
However, there is a key change the body goes through when carbs are brought right down, and that is the increased production and potency of ketones. Unlike triglycerides, ketones can get through the blood brain barrier and supply the brain with up to 75% of its energy needs.
The remainder of the energy needs can be met easily through recycled lactate, or glucose produced endogenously from the glycerol backbones of triglycerides.
More importantly, swapping dietary carbs for ketones isn’t a case of just plugging in a different energy supply.
Ketones produced from your fat stores and animal fats don’t come with the baggage of plant toxins and pesticides that you’d get from carbs.
They provide a steady and bottomless supply of energy that you won’t get with the constant power cuts that come with carbs, since you have at least a hundred thousand calories of fat tucked away, compared to just 2000 calories of glycogen.
But perhaps most importantly, ketones are a more efficient source of energy than carbs, and exert many neuroprotective effects by balancing the inhibitory and excitatory neurotransmitters, quelling free radical damage, and both fortifying and revitalising the mitochondria that run the whole show.
So in every sense, carnivore won’t lead to brain fog. Because ketosis is the cognitive upgrade. There’s a reason that babies are born in ketosis. And there’s a reason the brain chooses ketones over glucose when given the choice.
Verdict
The brain only needs carbs when you eat carbs. Otherwise it is perfectly happy to use ketones for the majority of its energy requirements, while producing its own glucose to make up the difference. And due to the many effects ketones have as miracle-signalling molecules, you wind up smarter and more stable for having made that switch.
15. Hypothyroidism
The nuked thyroid is another apparent fat flaw of long-term ketosis that biomarker scholars love to bring up. Ketogenic diets quite reliably have been shown to lower T3 levels, which is active thyroid. Given that hypothyroidism leads to a cacophony of unwanted symptoms like feeling cold, hungry, lethargic, and fat gain, it’s understandable that people would be a little worried about this turn of affairs.
But unfortunately, this is where nuance comes in. Thyroid-Stimulating Hormone, or TSH, triggers the thyroid to produce T4, or inactive thyroid, and T3. If you were really venturing towards hypothyroid, and the body was struggling to produce energy, you’d expect to see TSH rising by a significant amount. The aforementioned study shows TSH staying stable. There are case studies showing TSH actually going down.
This state of affairs, along with the complete lack of evidence showing a causal role between ketogenic diets and hypothyroidism, appears to suggest that lowered T3 on carnivore is yet another case of function rather than flaw.
The reason for this is apparent once you accept that ketosis is a unique fuel state with unique ‘healthy biomarkers’. T3 basically scales with gluconeogenesis, so high T3 levels can often be a marker of stress, and increases the likelihood of muscle catabolism. Gluconeogenesis is stimulated by glucagon, which opposes insulin. In a ketogenic state, insulin is low, and glucagon is high.
This all has the effect of making ketosis hyperthyroid if T3 levels stayed up, since that would ramp up gluconeogenesis to excess degrees. Mechanistically, it maps out, alongside the fact that ketogenic diets have never been implicated with hypothyroidism. Then there’s the correlation between high T3 levels and shortened lifespans. As I’ve said, excess gluconeogenesis is a stress state.
Undereating on carnivore can actually hamper thyroid function, but that’s the case with any diet. That’s why the rule here is always to eat to satiety, and never to undereat fat.
An iodine deficiency, given that it’s a critical compound that goes into the making of thyroid hormones, can certainly be a problem. The soils are depleted due to erosion, meaning there’s less of this mineral in meat and milk. That’s further antagonised by the presence of the other halogens: bromide, chloride, and fluoride. These are pervasive in the environment, and will outcompete iodine for absorption.
There’s a fair chance that you’ll benefit from supplementing iodine for this reason. But once again, it’s not a fault of carnivore. This is systemic.
Verdict
Carnivore can be expected to lower T3, but it simultaneously does not raise TSH, which would be the case if there was a problem with energy production. In a ketogenic state, ‘normal T3’ would make you hyperthyroid.
16. The Inuit Adapted To Suppress Long-Term Ketosis
Ever since the Arctic explorer Vilhjalmur Stefansson wrote his book “Not By Bread Alone”, the Inuits have held public fascination by their ability to show perfect health without eating any plant foods, let alone completing rainbows.
Because crops don’t tend to grow very well in the frigid wastelands that the Inuit inhabit. Chronic diseases only became a problem after the colonists came along and began to push processed junk into their food supply. Until that unfortunate turning point, the Inuit were completely reliant on meat and fish.
But there is yet another biomarker that makes people question the safety of long-term ketosis. The Inuits exhibit a variant of the CPT1a gene that suppresses fat oxidation and ketogenesis.
Now if you’re a believer in the idea that long-term ketosis is inherently detrimental, then this makes perfect sense, and forms the ideal gotcha moment that you can stow away for future debates against carnivore zealots.
Here’s the rub. Aquatic foods like seal and fish have high concentrations of PUFAs, and these fats raise ketone levels significantly more than saturated fat. The existence of the CPT1a gene is an adaptation to prevent ketone levels from going too high, offering protection from the harmful end-products of PUFA oxidation, and potentially a way to divert more fatty acids towards heat production.
Verdict
PUFAs increase ketone levels. The Inuit have adapted to a PUFA-rich diet by lowering fat oxidation to the point where they’ve nullified the artificially high levels of ketones. Like T3, it’s another case of the body being exceptionally adept at finding ways to maintain homeostasis.
17. Excess Iron
Despite 25% of the population of the world being iron deficient, there are plenty that have concerns with the potential of iron overload on a carnivore diet. Beef is stacked in iron, so much so that you can hit your daily requirements with just a 300 gram serving.
Excess iron can lead to symptoms like nausea, constipation, and stomach pain, and can even prove fatal, hence why parents are advised to keep iron supplements out of the reach of kids.
But that doesn’t mean that having extra steak is going to gradually pull you towards iron overload. The absorption of heme iron in beef is regulated in accordance with your iron needs. The more replete your hemoglobin levels, the lower the absorption of iron.
Having high ferritin levels, which safeguard you from iron, also doesn’t mean you’re getting too much iron from the diet, since it’s an acute-phase reactant that rises in response to inflammation. Hence why 90% of the cases of high ferritin levels are down to chronic alcohol consumption, metabolic syndrome, obesity, diabetes, malignancy, infection and inflammatory conditions.
The only situation where dietary iron can be problematic, comes from hemochromatosis, which is a genetic condition that causes too much iron to be absorbed and stored. In such a case, it would be prudent to stay away from liver, which has more than twice the iron content of steak.
Hemochromatosis itself is most common in populations who historically consumed a lot of dairy, and also lived in northern climates with recently glaciated, iron-depleted soils. Calcium and casein interfere with iron absorption, and therefore the mutation could have been an adaptation to get past that interference.
Verdict
The absorption of iron is well-regulated, and a high-iron diet can only be an issue if you have hemochromatosis. In which case, the smart play wouldn’t be to avoid red meat, but avoid organ meats and add more dairy instead.
18. Chronic Cortisol
There’s a gigantic chunk of evidence-based practitioners that still think of ketosis as a short-term emergency state that shouldn’t be allowed to outlast its welcome. One of the reasons they’ll offer up for this is chronically elevated cortisol levels, or dysregulation of the HPA axis.
In other words, ketosis puts you in a high stress state that isn’t being allowed to subside, leading to symptoms like fatigue, irritability, and insomnia.
This maps out in the mechanism by which the body increases cortisol to stimulate more gluconeogenesis and make up for the lack of incoming glucose. Low carb diets have also been shown to increase resting cortisol levels.
Right up until the three week mark, after which they return to normal. There are larger spikes after exercise, but acute hormonal shifts aren’t the issue. It’s when they’re chronically elevated or suppressed that you’re looking at dysfunction.
So that’s another danger that’s been blown out of the water. The adaptation phase from high carb to carnivore can absolutely be expected to cause fluctuations in markers. You’re moving across into fat-burning pathways that have long been dormant. It’s the long-term symptoms and markers that matter when you’re assessing the merits of a diet.
Verdict
Carnivore can raise cortisol levels, but only in the initial adaptation to the diet, hence the whole issue of keto flu that many have to wade through in order to reach the land of milk and honey. Long-term carnivore will not raise cortisol levels unless you’re simply undereating. But that’s a fault of the person, not the mechanisms of the diet.
19. Muscle Atrophy
Carbs are seen as a necessary part of muscle building by many, owing in large part to the love affair between bodybuilders and white rice. I’m not going to stick my neck out and say that you can step on the Mr Olympia stage without needing any carbs. But I’d definitely make the case that carbs are vastly overrated, and that carnivore is still perfectly capable of building elite physiques.
The argument for the necessity of carbs comes down chiefly to insulin’s effect on MTOR, and glycogen depletion’s effect on lowering motor recruitment. Insulin is needed to activate the MTOR switch, which drives the process of anabolism.
But while carbs produce the strongest insulin signal, you can still get sizable spikes from protein and dairy, of which carnivore can have plenty. Meanwhile, MTOR can also be activated by the amino acid leucine, one found in high amounts in animal foods.
You can certainly wonder as to whether carbs produce longer spikes in MTOR, but it’s likely marginal.
Glycogen depletion is the more interesting one, as muscle fibers that have been depleted of glycogen will force the body to lower motor recruitment in that muscle. This can be a problem considering that full motor recruitment is a critical ingredient in the growth stimulus of training, and carnivore happens to be low in the glucose that goes towards glycogen depletion.
There are studies showing that keto-adapted athletes don’t show signs of glycogen depletion, signifying that the body becomes better at conserving glycogen after a few months on the diet.
But muscle glycogen doesn’t function like a gas tank, and there is evidence that there can be severe localised depletion during training even when overall reserves are stable. You might be at 70% capacity, with some fibers nearing full depletion.
This is a short-term problem that might need incoming carbohydrates to provide the quick solution, since protein metabolism is painfully slow and can take 6-8 hours to produce a sliver of glucose.
If you’re training at high intensities for long durations, then it’s certainly possible that you’d benefit from some targeted carbohydrates during workouts. This is something I’ve championed in several articles in my blog.
Except we have one more spin. As far as strength and hypertrophy training goes, the best route is low volume. Meaning heavy loads, with low reps, and for a low to moderate amount of sets.
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This will not deplete glycogen in a keto-adapted system, since lifting in 10-20 second bursts will predominantly use the phosphocreatine system rather than the glycolytic system. I’m not arguing that glycogen isn’t used here, merely that it’s not the driving force, and that the demand is going to be so low that gluconeogenesis can easily foot the bill.
As for protecting against catabolism, a ketogenic state is inherently muscle-sparing. We have a few reasons for that.
1. High T3 levels are catabolic – Since T3 increases gluconeogenesis, which can eat into the muscle tissue, carnivore gets a beneficial rub by lowering T3 levels. Which is a hard sell for the biowizards that insist low T3 signals doomsday.
2. Ketones spare amino acids – Ketones spare amino acids from being oxidised for energy, allowing a greater percentage of your protein intake to go towards tissue synthesis and repair.
3. Ketosis prefers to use glycerol and lactate to make glucose – As opposed to glucose, meaning that the amino acids in your steak aren’t going to spike your blood sugar. The body would rather use fats and recycled lactate to maintain endogenous glucose production. Once again, the outcome is muscle-sparing.
Verdict
Carnivore is perfectly competent at building muscle, and doesn’t come with drawbacks unless you’re using high volumes and high intensity cardio. In which case, it’s worth considering the merits of targeted carbs during those workouts.
Carnivore is also muscle-sparing due to the state of ketosis, which means you’ll likely need even less protein than the standard 1 gram per kg of lean body mass recommendation.
20. Reduced Gut Diversity
One of the most enduring myths in dietician folklore is the idea that you need to eat 20 different plants every week to cultivate a blossoming microbiome with all the special species that will make you thrive.
On one hand, the microbiome is unimaginably important for our wellbeing, thanks to the gut brain axis.
But on the other, the science behind the microbiome is still stuck in the dark ages, and anyone who speaks with confidence about the ascribed benefits of a particular strain of bacteria, doesn’t in fact know anything.
It appears intuitive to assume that a carnivore diet will result in reduced gut diversity, due to the lack of variety in the diet, and the absence of fiber’s tendency to fertilise everything it comes across.
To this date, there’s only been one study on the gut diversity of a long-term carnivore, a case-study from 2024. It showed that the individual had no change in alpha-diversity, beta-diversity, and gut functionality when compared against the control group.
Another study comparing a vegan-rich diet and a meat-rich diet, found no significant changes in alpha and beta diversity between the groups. This should further serve to underline the fact that we don’t know enough, and a fiber-rich diet doesn’t mean you’ll have greater diversity, or that a greater diversity would be inherently a good thing.
Any claim that carnivore can’t feed the gut microbes without fiber is instantly quashed by the existence of ketones, butyrate, and collagen, which can all provide the microbiome with the fuel it needs to thrive.
Furthermore, carnivore neglects to add all the inflammatory baggage like fructose, lectins and glyphosate that irritate the intestinal tract, worsen SIBO and dysbiosis, and any symptoms of a beleaguered gut.
The gut can only heal when it is given the respite it needs, and the building blocks to repair the damage. Carnivore solves both of these problems.
Verdict
Carnivore hasn’t been shown to lower gut diversity, but it will improve gut health by removing the inflammatory triggers, the fiber that fertilises your bad gut bugs, and providing the nutrients needed to heal.
21. Phytonutrient Deficiencies
There are no essential nutrients that can’t be accessed from animal products. Phytonutrients are ‘plant exclusives’, but none of them are essential. They are simply curious nutrients that may or may not achieve the benefits they are advised as offering, and may well create more problems than they’re worth.
Isoflavones that are found in foods like soy and honey, can have estrogen-like effects, reducing testosterone and causing hormonal imbalances. Yet, they are held up by dieticians as anti-carcinogenic. Tannins found in tea are said to be antimicrobial and antioxidative, but block the absorption of key nutrients, opening up deficiencies.
And just so I can muddy the waters a little more, phytonutrients are found in plentiful amounts in grass-fed meat and dairy. They’re not actually plant-exclusives. So a carnivore diet does not force you to miss out on them.
If anything, it’ll likely just serve to detoxify the worst and keep the best. Because that’s functionally what sets ruminants apart from monogastric animals. They have the sophisticated digestive tract that’s specially suited to detoxifying plant weaponry and turning it into prime human nutrition.
Verdict
Phytonutrients aren’t essential, but grass-fed meat and milk has plenty in case you feel like you’re missing out.
22. High Cost
Carnivore is often portrayed as a diet that’s simply too expensive for many to follow. And sure, if you eat nothing but ribeyes every day, including trips to steakhouses, then the costs will rack up pretty quickly.
But budget isn’t really a valid excuse here. There are plenty of affordable foods that don’t drop short on nutrition or even flavour.
1kg of 25% ground beef costs me £5.18.
250g of cheddar sets me back £1.50.
6 large eggs are £1.75.
That’s 4000 calories for £8.43. 276 grams of protein. 324 grams of fat.
I don’t want to be an elitist, because I know there will be people hugging the poverty line in a Peruvian village that will still struggle. But anyone reading this article should be able to afford that.
Verdict
This diet can be as expensive or as cheap as you want it to be. But one thing that’s guaranteed, whatever price you pay will balk in comparison to the amount you’ll saved on supplements, eating out, and on medical bills.
23. Disordered Eating
Another label that gets frequently thrown at carnivore, is its restrictive nature. At the surface level, you can see the point. You’re avoiding all plant foods, which basically comprise 90-95% of the food products in the supermarket. You may have to turn down the offer of a cold beer at a barbeque. Takeaways are basically dead in the water.
From this angle, it’s a restrictive diet, which can make it appear orthorexic, which is an eating disorder where the person obsessively eats ‘perfect foods’ to the detriment of their physical and mental health.
A carnivore diet does not lack essential nutrients, because plant foods do not contain essential nutrients that we can’t access in better forms from animals. As long as you’re not undereating fat, there’s no risk of your health taking a turn for the worse.
More importantly, while carnivore is restrictive at surface-level, the end result of eating sources of total nutrition to complete satiety, and the abstinence from inflammatory plant foods, is liberation. You’re signing up for more energy, stable wellbeing, a leaner and stronger physique, the remission of chronic diseases, and the suppression of a whole host of autoimmune diseases.
The reason I’ve continued to eat this for five years, is because carnivore lets me feel my best, and perform at my best.
If I do indulge in a carb here and there, I don’t sweat over the details or the consequences. Because I know that I’ll be fully motivated to going back to the same way of eating at the next meal, and that any inflammation will quickly subside.
Verdict
Carnivore isn’t an eating disorder, or restrictive. It’s liberating, and its entire purpose is to enhance your lifestyle.
24. High Environmental Footprint
Most people still assume implicitly that livestock farming is the most wasteful form of agriculture, especially beef and dairy.
Cattle are the architects of climate change, since they belch out methane that is 25 times more potent at warming the planet compared to C02. They drain our precious water reserves, costing 15,000 litres to produce one pound of meat. They require much more land than any other protein source.
It’s these issues with cattle farming that have buffeted campaigns to bring down red meat consumption and thereby pull the planet back from its imminent destruction. But I’m not going to stand here and say that these claims are exaggerated. It would be much more accurate to call them statistical lies.
Methane might be more potent than C02, but it’s a flow gas that exists within the biogenic carbon cycle, and only stays in the atmosphere for 12 years, upon which it returns to the ground, waiting for the chance to be pulled up into the roots of a grass, and back into the maw of the next cow.
C02, on the other hand, has been locked away in the earth’s crust for hundreds of millions of years, and stays in the atmosphere for thousands of years. From any angle, it is the bigger threat.
Whereas cattle are just doing what ruminants have already done in even larger numbers in prehistory, and aiding the sequestration of carbon in the soil thanks to their pooping and stomping. It didn’t end the planet then, and it won’t do it now.
The water footprint of beef happens to include any rain that happens to fall on the field that the cow is roaming around in. That makes up more than 90% of beef’s water consumption. Only 4% actually comes from the tap. Which yields pitiful numbers when compared to the likes of almonds and avocados.
The land used by cattle might be vast, but that underlies the inescapable fact that two thirds of the agricultural land in the world can only be used for grazing. It’s either too steep, too rocky, too dry, or too infertile to plant crops.
So if we weren’t using all that land for grazing ruminants, we wouldn’t be able to use them for any other form of food production.
Finally, there’s the allegation that beef uses up too much valuable feed. Which is a ridiculous assertion, when considering the cattle are mainly fed grass, and only fed low-quality grains over the last few months. Only a small amount of that grain could be classed as edible. Most comes from byproducts and crops that wouldn’t meet the standard needed to end up in a supermarket.
One study found that grass-finished beef produced 1600 times more edible protein than it consumes. Grain-finished beef produces double what it consumes. Either way, it’s a huge net profit.
Verdict
Beef isn’t a wasteful product. It’s as frugal as it gets.
It uses mostly rain water, with very little tap water.
It makes use of land that can’t be used for any other form of food production.
It replenishes the topsoil and sequesters carbon.
It produces at least twice the edible protein that it consumes.
It uses up byproducts from crops that would otherwise go to waste.
It provides plenty of byproducts that serve society, like leather.
25. Grain-Fed Beef Isn’t A Health Food
Not many things rankle me these days, but I do get a little wound up at the elitism of meatfluencers waxing lyrical about getting beef from cows that have lived out their days in the foothills of the Himalayas while being massaged every evening by holistically-trained Pandas.
There’s nothing wrong with grain-finished beef. Yes, you can argue that there are improvements in nutrients with grass-finished, but these are marginal. Grain-finished beef have still spent 90% of their lives on pasture, dining on grass. It’s only the last 90-120 days where they’re switched to grain. And even then, these are ruminants we’re talking about. They are the leading edge of sophisticated digestion, with the capabilities to detoxify and upcycle virtually anything we throw at them.
A pig fed grain, and a cow fed grain, are completely different beasts. The former is dangerously high in PUFAs, the latter is still extremely low. The linoleic acid in 100 grams of grass-finished beef has 0.067 grams of linoleic acid. Grain-finished still only has 0.32 grams. It’s much higher as a percentage, but completely insignificant as an absolute figure. The same goes for Omega 3.
Verdict
The most nutritious food on the planet is grass-finished beef. The second is grain-finished. So don’t sweat over the perils of getting your meat from the supermarket. Get whatever version is convenient for your location, your wallet, and your tastebuds.
26. Animal Welfare Concerns
So you can eat carnivore for your health, as long as you can make peace that animals have to suffer to get you there, right? Some people might be content with such a compromise, but it’s completely unnecessary. You can be on a carnivore diet while still sleeping soundly at knowledge, armed with the knowledge that you’re doing what’s best for the animals.
Meat-eating gets framed by many as a crime of conscience, and we’re all well aware of the images and videos that get circulated showing livestock animals living in desperate conditions and enduring unimaginable cruelty, alongside staggering statistics of the number of animals that are slaughtered every day to put meat on your table.
I’m not about to say factory farming is perfectly fine, and that animals living in confined feedlots are having a whale of a time. But the contribution of unethical ruminant agriculture has been grossly overrepresented.
Only 1-4% of the beef you buy in the UK is coming from factory farms. The vast majority of beef cattle spend most of their lives out on pasture, and the UK has some of the highest livestock welfare standards in the world. Growth hormone is illegal, and antibiotics are strictly regulated.
Lamb meanwhile, gets more than 95% of its diet from grass, making it the most nutritious and ethical meat you could possibly buy in the UK.
Chicken and pork are a different story, since most of them are factory-farmed, but that’s just another reason to fixate on red meat as the main source of nutrients on a carnivore diet.
Verdict
The cattle in the UK have plenty of space, free healthcare, free food, protection from any predators, and have one bad day they never see coming.
27. Hair Loss
I realise that I’m not the best person to tell you that hair loss is nothing to worry about on carnivore. But I started the carnivore diet at the age of 26, and I already went bald at 23. I didn’t see any point in hiding my emerging crown, so I just shaved the rest off and never looked back.
My hair was diabolical, and my head is magnificent. No regrets.
But to get back to carnivore and hair loss, there are some rumblings that this diet hastens the process. Nutrient deficiencies are one, but I’ve basically covered and debunked all of the potential deficiencies in this article.
Low thyroid is another, but that’s already been addressed in this one. Then there’s telogen effluvium, which is stress-related hair loss that could be brought about by undereating or a sudden dietary transition. This is likely the source behind most people experiencing hair loss on carnivore. The former happens to be the biggest danger of a carnivore diet, but not at all the fault of the diet itself. The latter is a temporary condition at worst, and will soon subside, upon which the hair will grow back fast and thicker than before.
On the other hand, there’s plenty to suggest that carnivore can aid hair growth. Hair is made of collagen, and carnivore is absolutely stacked in it.
Free radicals can seriously affect the health of your hair, by damaging hair follicles, making your hair weaker and more prone to falling out. Oxidative stress can also harm the cells that produce pigment in your hair, which can lead to premature graying. Over time, this damage can disrupt the normal hair growth cycle, causing your hair to thin and grow more slowly. On top of that, free radical damage can irritate your scalp, leading to inflammation and other scalp issues like dandruff or discomfort.
A carnivore diet, armed with the power of ketosis and free of the seed oil scourge, goes a long way towards quelling free radicals and protecting the cells from free radical damage. This is why there happen to be numerous anecdotes of people reporting their hair actually growing back on a carnivore diet.
Verdict
Carnivore can cause initial hair loss due to telogum effluvium, which is a temporary condition that can be caused by under eating or drastically changing the diet. This will resolve in months, so stay the course, and make sure you don’t under eat.
Wrapping Up
Carnivore isn’t immune to issues, but it is the safest and most idiot proof diet out there. After five years on this diet, alongside copious amounts of research, I’m pretty comfortable with dying on this hill. This diet has an unbroken track record going back millions of years.
It exempts virtually all the foods that can cause inflammation and digestive issues, with the exception of dairy. It prioritises the food with the most dense and varied nutrients, and the least toxins: red meat. It emphasises the most stable fuel source, and the body’s favoured form of energy storage: saturated fat.
Carnivore is the ultimate factory reset. A physical and therapeutic overhaul that gets you back to performing and feeling at your best.
Much of this can go wrong if you attempt this diet with lean meats, but I’d maintain that such a diet wouldn’t be carnivore.
Because carnivore is, through its ancestral origins, a high fat diet. We didn’t get here by chasing turkey and jungle fowl through the undergrowth. We got here by hunting and slaying the biggest and the fattest animals on the land.
If you respect this fact that defines the makeup of the diet, then you’ll be setting yourself up to succeed. You should absolutely expect some turbulence in the first few weeks, even months, of cutting out plants. Decades of damage don’t unravel in an instant.
But the purpose of this article was to underline the fact that the fear mongering over the long-term effects of this diet is completely unwarranted. People are either misinterpreting the data, or just opting for the brute-force approach of fabricating their arguments out of thin air.
The issues with carnivore are in the short-term, and are transitional. In the long-term, it’s the safest one out there.
Read More Here
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