A Deeper Look at the Carnivore Diet: Does the Hype Outpace the Evidence?
Authored by Elliot Reimers, M.S.(C), CISSN, CNC
The Carnivore Diet: Should You Be Eating Only Meat for Better Health?
As its name implies, the carnivore diet consists of animal meat. That's it — just meat, predominantly red meat such as rib-eye steak, ground beef, pork chops, and fatty organ meats. Fish and other animal foods like eggs are also allowed, sans dairy products.
To some, the carnivore diet might sound like an unhealthy way of eating. For others, it seems to be a panacea for chronic disease.
But is eating only animal foods yet another example of people swinging the pendulum way too far in one direction? Should you follow the carnivore diet to improve your long-term health, or should you eat a plant-based diet? What about an omnivorous diet?
When comparing veganism to the carnivore diet and those who eat both plant and animal products, there's much to consider. If you're new to the world of fitness and its unceasing trends that go against the grain, this article will give you a brief primer on the carnivore diet as well as the purported health benefits and potential risks of eating only animal foods in lieu of plant foods. (For the sake of brevity, we won't be comparing the ethical implications or evolutionary aspects of veganism compared to carnivore eating.)
What Is the Carnivore Diet?
Even if you loathe fruits and vegetables, chances are you never anticipated people claiming that meat has more health benefits than plant foods. But here we are with the carnivore diet, which strictly eschews plant foods in favor of animal foods.
Quite simply, the carnivore diet is an animal-based, plant-free diet, not too unlike the Paleo diet. However, you won't be eating any berries, raw veggies, nuts, or seeds on a carnivore diet like you may when following Paleo or a ketogenic diet.
The carnivore diet consists of nothing but animal foods; it is a literal "meat diet." Your grocery shopping list will be pretty simple: grass-fed organ meats, fish, and high-fat steaks. You can also eat certain animal products like eggs and bone broth, but no dairy.
Intuitively, eating meat only means you'll be following a low-carb diet. Hence, the carnivore diet is a unique type of ketogenic diet. Whether or not this paradoxical way of eating is sustainable in the long-term is anybody's guess.
A quick Internet search makes it evident many people think a "meat diet" is the holy grail for long-term health and vitality. Frankly, these individuals carry the same passion for meat as vegans do for plant foods.
That seems so bizarre, doesn't it? But after you read more about the carnivore diet, one can't help but wonder if the health benefits are based on empirical evidence.
Is Eating Only Meat Healthy?
Arguably the biggest criticism of the carnivore diet is that it leaves people liable to micronutrient deficiencies. After all, plant foods like fruits and vegetables are Mother Nature's most plentiful source of vitamins and minerals, right?
Well, yes and no.
Technically, humans can meet all their vitamin and mineral needs without plant foods. In other words, eating only meat is feasible from an essentiality standpoint.
The catch is that vitamin C and a select few other micronutrients are less abundant in meat. Also, a meal plan with nothing but meat, particularly red meat, will come with excess amounts of iron.
Curiously though, the expected micronutrient imbalances of a carnivore diet are generally not a cause for concern based on the current body of evidence . The carnivore diet may even be therapeutic for certain subpopulations.
For example, the carnivore diet might be used as an elimination diet in people with chronic disease, food allergies, and gastrointestinal issues arising from plant foods.
Thus, one of the purported health benefits of the carnivore diet is that it helps treat gastrointestinal maladies like irritable bowel syndrome (IBS) by eliminating the culprit fibers found in plant foods.
Dietary fiber and phytates from legumes, for example, are also known to interfere with micronutrient absorption . Therefore, a carnivore diet may prove beneficial for people who can't tolerate fibers from plant foods or those who suffer from micronutrient malabsorption issues.
Now, before you go and roast up some more organ meats for breakfast, lunch, and dinner and toss out all the fruits and vegetables in your house, there are finer points to consider when it comes to the carnivore diet.
Is the Carnivore Diet Safe?
The main organ indicted in the safety of high-protein diets like the carnivore diet is the kidney — the veritable “trash collector” of the human body. Metabolic waste from various physiological processes, like the urea cycle and cellular respiration, are conveyed to the kidneys via the circulatory system and filtered at the nephron — the functional unit of the kidney.
Metabolites and chemicals filtered at the nephron are either resorbed into the bloodstream or transported via the ureters to the bladder for urinary excretion. Thus, the kidneys are vital to detoxing the body.
Since amino acids are nitrogen-containing compounds, eating a high-protein diet means the kidneys have to work a little harder to filter all the "extra" nitrogenous waste. While the kidneys do have to “work harder” when you consume a higher protein intake, it’s not in the sense that most people assume.
Healthy kidneys can tolerate a relatively high-protein diet without much issue, at least in the short-term . There is also no compelling evidence that higher protein intake leads to renal impairment in the long-term .
The vast majority of metabolic and nitrogenous waste is eliminated via urine, not feces, as many people assume. The protein content in your urine shouldn't change much even if you follow a high-protein diet. In fact, most of the electrolytes, glucose, and amino acids filtered by the kidney end up being resorbed into the circulation instead of being excreted in urine.
It’s important to note that the kidneys actually do much more than help rid the body of toxins and nitrogenous waste. They also control chemical and fluid balance in the body, regulate your blood pressure, blood sugar, and create new red blood cells. Hence, the composition of someone's urine and fecal matter can vary significantly based on what they eat, their lifestyle habits, and how much they weigh.
Nevertheless, those with renal dysfunction most certainly need to keep an eye on their protein intake. If your kidneys aren't working properly, eating a high-protein diet, especially one that contains solely animal foods, will only make things worse.
Does Eating Meat Increase the Risk of Colon Cancer and Heart Disease?
According to epidemiological research, frequent consumption of red meat is associated with colon cancer and heart disease [5, 6]. However, it's unclear whether that's a ramification of the meat itself or the way it's prepared.
Cooking meats at high temperatures creates putative carcinogens known as heterocyclic amines (HCA) and polycyclic aromatic amines (PAH). Charring, barbecuing, and smoking meat increases the production of these compounds .
If you follow the carnivore diet, it's imperative to reduce the HCA and PAH content of meat by using low-temperature cooking methods, such as roasting, boiling, steaming, microwaving, and stewing.
Furthermore, bacteria in the gut ferment protein from animal foods to create triethylamine oxide (TMAO), which is implicated in the progression of atherosclerosis . Excess TMAO production could explain why meat-eaters tend to be at a greater risk of colon cancer and heart disease than vegetarians.
For those who eat meat regularly, it's prudent to consume plenty of prebiotics (digestion-resistant starch, inulin, oat bran, wheat bran, etc.) to reduce protein fermentation in the colon and inhibit the gut bacterial formation of TMAO.
Alas, the carnivore diet prohibits plant foods so that's not an option. The next best alternative is to take a probiotic supplement. Using a daily multivitamin may also be wise.
The Carnivore Diet as a Ketogenic Diet
A carnivore way of eating is inherently as close to a zero-carb, zero-fiber diet as you can get. As such, if you follow the carnivore diet, you're also following a ketogenic diet. Red meat and pork, for example, are high-fat animal foods with virtually no carbs.
But those who follow the carnivore diet also eat quite a bit more protein and saturated fat than their vegan counterparts.
High saturated fat intake is associated with kidney dysfunction and chronic kidney disease . In addition, red meat tends to be a much more acidic protein source than plant proteins. It doesn't matter if you're eating nothing but grass-fed organ meats; the increase in acid load and saturated fat from a carnivore diet will subject the kidneys to quite a bit of "overtime" work, so to speak.
We also can't forget that organ meats are also rich in sodium, whether naturally occurring or from added seasoning/salt. While there isn’t sufficient evidence to suggest that a high-sodium diet actually causes chronic disease of the kidneys, it's something to consider for those with preexisting renal dysfunction and/or high blood pressure — especially before jumping on the meat diet bandwagon .
On the plus side, since a carnivore way of eating is also low-carb, the kidneys won't have to work as much to filter glucose. This creates a bit of a double-edged sword for both plant-based dieters and carnivore dieters; a low-carb, high-fat meat diet won't be without drawbacks, but neither will a plant-foods only approach.
The question remains: Should you follow the carnivore diet? Or is a vegan way of eating healthier?
Plant-Based vs. Animal Foods: What Science Has to Say
When comparing a vegan diet to a carnivore diet, there is much more scientific and clinical data to warrant the plant-based craze. If you absolutely had to pick one extreme or the other, odds are a plant-based diet would be the wiser choice in the long run, particularly for mitigating chronic disease risk and improving longevity.
Though, many people argue that a vegan diet has notable flaws. You can find all the essential nutrients in plant foods, but strict veganism contributes to micronutrient deficiencies, particularly of vitamin D, iron, zinc, and calcium [11, 12, 13].
That being said, a recent research review states that "results so far suggest that the long-term health of vegetarians is good, and may be better than that of comparable non-vegetarians for some conditions and diseases such as obesity and heart disease." Note that this review pertains to plant-based vegetarian diets, not strictly vegan diets.
There are gaps in our understanding of the long-term health effects of raw vegan diets. In any case, there isn't much "wrong" with a plant-based diet plan.
While some swear by the carnivore lifestyle, it's mostly just another example of the extremes people will go to when they read anecdotes on the Internet about how Joe Rogan or some other lionized individual flourishes on a trendy fad diet.
At this point, there is (very) limited human data on eating meat only; most of the research comprises clinical case studies or retrospective analyses of nomadic Artic cultures. Obviously, observations from such studies need to be taken with a grain of salt.
To be fair, a plant-free meat diet appears to be therapeutic in rare circumstances, such as patients with autoimmune diseases that require highly specific nutrient intakes. In small subpopulations, following a meat diet could also be beneficial as a short-term nutritional intervention.
All we can confidently say is that humans can meet all of the acute essential nutrient needs from animal foods, especially organ meat. However, the long-term health benefits, let alone the consequences, of the carnivore diet remain a mystery.
Don't misconstrue that to mean the carnivore diet might not be suitable for you. Frankly, most carnivore diet advocates praise the health benefits of the animal-based lifestyle. Whether or not this way of eating will do the same for you is something only you can determine.
Many people eat high-protein fatty meat around the clock with seemingly no health consequences. Does that mean it's optimal to rely exclusively on animal foods? Of course not. Many diets "work" to a degree. Just remember that people can be in great shape and pass their medical checkups with flying colors not necessarily because of their methods but in spite of them.
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