What is the Carnivore Diet?
Potential Benefits and Concerns

We in the keto/LCHF community are accustomed to being the oddballs among our friends and families. We’re not scared of butter, bacon, and red meat. If we put anything in our coffee, it’s heavy cream or coconut oil — no skim milk for us! And if we have the urge to snack, it’s not on popcorn or candy, but on pork rinds, nuts, or deviled eggs. Most of us, however, still enjoy a variety of non-starchy vegetables, and maybe even small amounts of berries and other low-sugar fruits. But what happens when you get rid of that — all of it? What happens when you remove all plant foods from your diet?

A growing number of people are doing exactly that, and the results so far are interesting. These people have adopted the carnivore diet, also called “zero carb.”

What is the Carnivore Diet?

The carnivore diet is the opposite of veganism. Instead of eschewing any and all foods of animal origin, strict carnivore dieters avoid all plant foods. Not just the refined carbs and starchy vegetables any low carb or keto dieter would avoid, but also the ones typically considered totally fine, such as mushrooms, avocados, nuts and seeds, and non-starchy vegetables. And even though pure oils can be considered “zero carb,” strict carnivores also avoid olive oil, coconut oil, and other plant-sourced fats. Some carnivores are a bit more flexible and make exceptions for coffee or tea, wine and spirits, and occasional spices and seasonings for flavor.

Some include eggs and dairy, but most stick exclusively to animal flesh, especially fatty beef, pork, lamb, fatty fish (salmon, mackerel, sardines, herring) and seafood. Some eat only muscle meats, while others include organ meats and bone broth. Of those who eat exclusively muscle meat, many opt solely for beef, while others consume lamb, pork, poultry, seafood, wild game, and other animal foods in addition to beef.

Wait… No Vegetables? None at All?!

Eliminating all plant foods from your diet sounds extreme, but it’s not quite as crazy as it seems at first glance.) For starters, we in the keto community already accept that much of what we were taught about “healthy diets” is misguided, and in some cases, flat-out wrong. The carnivore diet takes things a step further and challenges even some of the tenets we believe to be true — for example, fiber being important for a healthy gut and proper GI function, or antioxidants in berries or sulfur compounds in broccoli and garlic being beneficial for health.

What if even more of what we believe isn’t true?

Why Would Anyone Follow a Carnivore Diet?

Carnivore is the ultimate elimination diet. For someone dealing with intractable health issues that don’t seem to get any better no matter what they try — including a ketogenic diet — a carnivorous diet is a straightforward way to eliminate the vast majority of the most common food allergens.

Elimination diet protocols are often complicated and intimidating. It can be a difficult balancing act to suss out whether you’re sensitive to gluten, FODMAPs, oxalates, salicylates, or some other compound in plant foods. It can be overwhelming and confusing to navigate a grocery store or restaurant menu when there are multiple things you need to steer clear of. With the carnivore diet, it couldn’t be simpler, because you eliminate all of that. It’s restrictive, yes, but no one can argue against its simplicity.

There are, of course, allergies and intolerances to animal foods. Some people are sensitive to eggs or dairy, allergic to shellfish, and some may be sensitive to histamines, which are compounds that may be present in animal foods, particularly ones that are cured or aged, such as cured meats and aged cheeses. (Histamines are also present in fermented vegetables and in small amounts in some fresh ones.)

So a carnivorous diet doesn’t automatically eliminate all potential dietary irritants, but if someone suspects one of these animal food sensitivities, they can design their diet to be free of eggs and dairy, and low in high-histamine meat products. In this sense, the carnivore diet is similar to keto in that it has certain guiding principles, but within those, it’s highly customizable.

Who Might Benefit From Going Carnivore?

Articles about the carnivore diet have featured stereotypical memes of a caveman (or a modern day “tough guy”) chowing down on a Flintstone-style bone-in ribeye. But what if this way of eating is no laughing matter? What if it can help restore health in ways no other diet has?

People who are giving the carnivore diet a try come from all different starting points: some were already healthy and fit on a low carb or keto diet and just wanted to try something different. Others had failing physical and mental health from long-term veganism. Others skip over more moderate approaches like Paleo or LCHF and jump into carnivore straight from a conventional high-carb diet.

Many former vegans are regaining health by going carnivore. This is unsurprising, considering the many nutrient deficiencies un-supplemented vegan diets frequently induce. When these people start getting higher amounts of more bioavailable iron and zinc, B12, pre-formed vitamin A, EPA and DHA, it’s no wonder they feel much better, physically and mentally.

But What About People Who Were Already Doing a Ketogenic Diet?

This may be the most surprising group experiencing substantial health improvements after trying the carnivore diet. While many people who switch to LCHF or keto have nearly miraculous improvements in a host of health conditions, some find that keto doesn’t quite take them all the way. They have noticeable improvements, but small and not-so-small symptoms persist. Among this group, some who’ve made the leap from keto to carnivore have reported complete resolution of issues that hadn’t fully cleared up with keto.

For someone following a ketogenic diet who still deals with bothersome signs and symptoms, ideally, the first step would be to work with a keto-savvy nutrition or medical professional who can help troubleshoot. Maybe there’s a relatively simple change they can make that they just hadn’t thought of. But for those who’ve already gone this route, and it seems like nothing makes a dent in those remaining issues — not even a truly well-formulated, nutrient-dense keto diet — it might be worth giving carnivore a try.

If the testimonials published on the “Meat Heals” website are any indication, a carnivorous diet seems to be especially helpful for people with intractable mood instability, digestive disorders, and dermatological conditions that had not responded to other strategies. It should be noted, however, that for now, these personal accounts are anecdotal and do not hold the same scientific weight as rigorous clinical trials. This being said, perhaps the growing number of these powerful personal stories will spur interest among researchers to start looking into this more seriously. This has already begun on a small scale: several people have reported dramatic improvements in various autoimmune conditions, and a group of doctors and researchers in Hungary (the Paleo Medicina group) are conducting trials with this type of approach for autoimmune issues.

How Does the Carnivore Approach Work?

The Evolutionary Perspective

Evolutionary history and several billion healthy people around the world show us that most people can consume a variety of plant foods with no obvious adverse effects on health or longevity. But there may be people who are sensitive to various compounds in plant foods that are innocuous to others.

The argument goes like this: everything alive wants to stay alive, at least long enough to reproduce. Animals have ways to defend themselves against predators, such as claws, sharp teeth, horns, and the ability to run or swim away.

Some plants have physical defenses, such as thorns and spiked leaves, but they can’t uproot themselves and run away. In order to protect themselves against predation, plants produce compounds that make them unattractive or even harmful to animals that might otherwise consume them — a kind of “chemical warfare.”

Some of these compounds — for example, oxalate, salicylate (1), solanine, goitrogens, phytic acid (2), and saponins — may have adverse effects on health. (In the case of oxalate and phytic acid, these compounds bind to certain minerals, hindering their absorption and thus reducing the usable nutrient content of foods that contain them.) Compounds called lectins (3) may play a role in the pathology of autoimmune disorders, especially rheumatoid arthritis. (4)

Food Sensitivities Not Resolved By Keto

Keto diets can include foods rich in some of these compounds, including eggplant, tomatoes, peppers, spinach, chard, coconut oil and olive oil. Someone diligently adhering to a seemingly perfect ketogenic diet might not experience an improvement in a particular condition until they eliminate foods they’re sensitive to — foods that might be totally fine for someone else, but which are problematic for them.

For someone who suspects they have an issue that an exclusively carnivorous diet might address in ways a strict keto didn’t, they can give carnivore a try for some length of time and then slowly, systematically reintroduce plant foods one at a time to see how they react to them.

Ketosis is Not the Goal

Ketosis is likely to result from a carnivorous diet, but it’s the not the goal. Owing to the complete absence of carbohydrate-containing foods (except for negligible amounts in animal proteins and small amounts in high-fat dairy foods), people following a carnivorous diet will likely be in a state of ketosis, but being in a ketogenic state is not the aim.

You might be wondering, “What about all that protein? Doesn’t that kick people out of ketosis?” Or, “What about gluconeogenesis? Isn’t all that protein going to turn into sugar?”

Probably not. Individual sensitivity to the effects of protein on insulin varies, but most people can eat a fairly high amount of protein without it interrupting the burning of fat or taking someone out of fat-adaptation. Some people might see their ketone level decrease slightly from a large protein intake, but since achieving and maintaining ketosis isn’t the goal of a carnivorous diet, this isn’t a problem. And it’s important to understand that a lower ketone level doesn’t mean someone isn’t still burning fat. (People who need to maintain therapeutic levels of ketones to help manage a medical condition such as epilepsy may need to watch their protein intake.)

For a fascinating and educational look at protein and its effects on insulin and the counter-regulatory hormone, glucagon, I recommend this video by Ben Bikman, PhD, a researcher and expert in cellular energetics at Brigham Young University.

For some people, the beneficial effects of a carnivorous diet might be the result of ketosis, but considering many people come to carnivore from already being keto, there are other mechanisms by which the carnivore diet might be exerting its effects. Chief among them is the aforementioned elimination of plant foods people didn’t realize they were sensitive to.

Beyond that, depending on the particular animal foods someone consumes on a carnivorous diet, it’s possible their diet is of higher nutritional quality than when they were low carb or keto, and almost certainly more than when they were consuming a standard Western diet. Instead of filling up on fatty coffees and low-protein keto treats, diving into steaks, pork chops, eggs, and seafood means that many people may be consuming more B-vitamins, iron, zinc, selenium, and other nutrients than they were previously. This could be a factor in people’s health recovery.

What About Fiber?

This is one of the first questions carnivores get asked. How do you poop? Surely you have to have fiber in your diet, right? If you’ve been following a low carb or keto diet for a while, you’ve long since realized that the human body can run just fine — maybe even better — without sugar and starch. But don’t we need at least some fiber from plant foods? From things like spinach, asparagus, or almonds? If you don’t have any fiber in your diet, how will you go number 2?

Just fine, apparently.

According to the Food and Nutrition Board of the Institute of Medicine of the National Academy of Sciences (5), carbohydrates are not an essential part of the human diet:

“The lower limit of dietary carbohydrate compatible with life apparently is zero, provided that adequate amounts of protein and fat are consumed.”

If carbohydrates are not essential, that means fiber is not essential, since fiber is a carbohydrate. But just because something isn’t “essential” in the diet doesn’t mean a diet completely devoid of it is optimal or desirable. You can survive without it, but that doesn’t imply you’ll thrive without it. For example, the only “essential” fatty acids in the human diet are linoleic acid (everybody’s dreaded omega-6) and the omega-3 alpha-linolenic acid. All the saturated and monounsaturated fats we enjoy so much in steak, bacon, butter, and cheese, aren’t technically “essential.” But life wouldn’t be nearly as delicious without them.

Contrary to conventional wisdom, fiber often makes bowel problems worse, including the one it’s recommended for most often: constipation! Some people with constipation benefit from reducing the amount of fiber they consume. After all, fiber is recommended for “increasing bulk” of the stool. But if your bowel is already full of material that’s not moving through in a timely manner, why would you want there to be more of it? (Note: this doesn’t mean fiber causes constipation. But if you are constipated for some other reason, making your stagnant stools even larger isn’t very logical.)

Other conditions related to intestinal function and colonic motility that might benefit from diets lower in fiber and irritating plant compounds include IBS and diverticulosis. (6, 7)

Bottom line: Contrary to popular belief, a high dietary fiber intake isn’t required to have healthy bowel movements, and while some people may benefit from a higher-fiber intake, other people suffering from certain bowel conditions might actually do better with less fiber.

What About Phytochemicals and Antioxidants?

Okay, fine. Fiber isn’t essential, and for some people, it might even be detrimental. But everyone knows fruits and vegetables are loaded with health-promoting antioxidants, right? Well, once upon a time, “everyone knew” that saturated fat clogged your arteries and that eating a lot of bacon and eggs was a surefire way to give yourself a heart attack. One by one, many nutritional sacred cows have been slain during the past few decades.

Still, surely — surely — we need plant foods because of the antioxidants they provide. Piles and piles of epidemiological surveys show that fruit and vegetable consumption is “associated with” good health and longevity. We need the anthocyanins in raspberries and blueberries, the sulforaphane in broccoli, the allicillin in garlic, and the curcumin in turmeric. Right?

Here again, when you start digging a little deeper, the science is less compelling than it’s typically reported to be. The effects that isolated and ultra-concentrated extracts of these compounds have on cultured cells in petri dishes may not be the same effects seen in living, breathing humans consuming reasonable amounts of whole foods that have to pass through the GI tract before their metabolites reach the bloodstream.

Dr. Georgia Ede’s article, The Antioxidant Myth, is an educational read on this issue, looking at the examples of pomegranate juice and curcumin (from turmeric) — two ingredients that make frequent appearances on the labels of “detox” drinks and antioxidant products. Her exploration of the weaknesses of the science shows us that sensationalist headlines about the power of some of these plant-derived compounds are misleading at best, and at worst, may actively harm public health when used to convince people to consume foods and beverages that are loaded with sugar, like fruit smoothies and baked goods studded with dried cranberries.

Some of our most powerful antioxidants are produced endogenously — inside us. And they’re proteins, made from amino acids. Glutathione, often called the body’s “master antioxidant,” is a tripeptide, made from the amino acids glutamate, cysteine, and glycine. Another key antioxidant, superoxide dismutase (SOD), is also a protein. Given the required building blocks — amino acids, and in the case of SOD, copper, zinc, and manganese — our bodies make these antioxidants; we don’t need goji or açaí berries to come to the rescue.

What about curcumin? Or ginger, rosemary, resveratrol, and the sulforaphane in cruciferous vegetables? (8, 9) Consumed in highly-concentrated forms, some of these may have a kind of pharmacological effect — meaning, they act almost like medication and may induce, upregulate, or inhibit various biochemical processes. (10) But that doesn’t mean we need to consume large amounts of them in order maintain good health.

In their description of the ten defining characteristics of a well-formulated ketogenic diet (WFKD), the PhD researchers at Virta Health do not claim that vegetables are an essential aspect of a ketogenic diet. Based on the criteria they list, it would be possible to construct a WFKD devoid of plant foods. In fact, they wrote, “Due to individual variations in carbohydrate tolerance, total daily carb intake can range from nearly 0 to 100 g/d…” (To be clear, nowhere have they recommended or endorsed a carnivorous diet; I am pointing out only that their criteria for a WFKD do not include a specific required minimum intake of plant foods.)

Other Fascinating Questions

In the keto community, we already knew that much of what’s considered “conventional wisdom” or “settled science” is up for debate. No, actually, all those whole grains aren’t so heart-healthy. And no, eating saturated fat doesn’t increase saturated fat in the blood. (11) But what else should we be looking at?

Dietary requirements are based on high-carb diets

This is one the most fascinating avenues the carnivore approach is opening for exploration. The dietary requirements — the amounts of essential vitamins and minerals we’re recommended to get daily — were established based on people eating mixed diets — that is, diets that contained a substantial amount of carbohydrate. It’s entirely possible that these requirements depend on the overall composition of the diet. The need for various nutrients on a diet composed of 50% carbohydrate (or more!) might be different from nutrient needs on a diet that contains little to no carbohydrate. We don’t know for certain.

One of the most interesting questions seemingly healthy carnivore dieters raise is whether the composition of a diet influences the micronutrient requirements of that diet. For example, among its other myriad jobs, magnesium is required for six enzymatic reactions in glycolysis, the first step in the metabolism of glucose. If your body is performing less glycolysis (not none, but less), it’s not unreasonable to speculate that the requirement for magnesium might be lower than for someone consuming a high carb diet. The same might be true for other nutrients.

We do know that people have been eating this way for years and they’re not keeling over from scurvy. There haven’t been exploding rates of osteoporosis or osteopenia among long-term carnivores who consume little to no dairy. It’s possible that eating an exclusively carnivorous diet changes the requirements for certain nutrients. This is already known to be true for vitamin C, which is — apart from fish roe and organ meats such liver, kidney and pancreas — only present in plant foods. It might be true for other micronutrients as well; that research remains to be done.

It’s also possible that the amount of certain nutrients in various animal foods has been underestimated or miscalculated. If so, people consuming exclusively animal foods may be getting more micronutrients than we would assume.

Caveats and Concerns About the Carnivore Diet

My advice regarding the carnivore diet is the same as my advice for any other change in diet: listen to your body. Pay attention to how you feel physically, mentally, emotionally, and cognitively. There will likely be an adjustment period, particularly if you’re switching to a carnivorous diet from a high-carb standard Western diet rather than from already being low carb or keto. After the initial adjustment though, if there’s been a noticeable decline in your energy levels, mood, or anything else you take to be part of your overall health and wellbeing, consider ending your carnivore experiment and adding plant foods back into your diet.

Long term data on modern-day people following exclusively carnivorous diets are scarce. But we could have said the same about ketogenic diets 30 years ago.

A lot is unknown at this time. There are far more questions than answers, and a great deal of speculation. Something to keep in mind is that we often see only the success stories. The people who do well on a carnivore diet shout it from the rooftops, while people who’ve fared poorly may be keeping it to themselves. To put it another way, we’re privy to the highlight reels, but there might be outtake footage that never gets aired. In the same way we don’t like people being told to “keto harder” if something isn’t working for them, “carnivore harder” is not a solution to a genuine problem.

If you develop troubling symptoms, don’t ignore them. Don’t attribute anything and everything that happens to you to your diet and assume you’re still in an adjustment period. But I would say this about keto as well — don’t ignore things that don’t go away. Don’t assume they’re “normal” parts of following a carnivorous diet, or any other diet, for that matter.

Please be aware: If you have a medical condition or are taking medication — particularly medication for high blood pressure or type 2 diabetes — especially insulin — you must be monitored by a physician. Dramatic dietary changes often necessitate reductions in doses or stopping medication altogether, sometimes within just days of implementation. (In the case of insulin, for some people reduction is required on the first day in order to prevent a dangerous hypoglycemic event.) Do not adjust your medications without medical supervision.

Resources to Learn More

This post is intended to be an introduction to the carnivore diet concept, not an endorsement of it or a recommendation for everyone to try it.

If you’d like to learn more about it and get guidance on how to implement this approach, here are some resources to explore that will give you information and advice from carnivore veterans who’ve been doing it for an extended period of time.

  1. Blog
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  2. Amy Berger, MS, CNS, NTP
  3. What is the Carnivore Diet? Potential Benefits and Concerns
Amy Berger, MS, CNS, NTP
Certified Nutrition Specialist and Nutritional Therapy Practitioner

Amy Berger, MS, CNS, NTP, is a U.S. Air Force veteran, Certified Nutrition Specialist and Nutritional Therapy Practitioner who specializes in using low-carbohydrate nutrition to help people reclaim their vitality through eating delicious foods, and showing them that getting and staying well doesn't require starvation, deprivation, or living at the gym.

Expert Article

This article was written by Amy Berger, MS, CNS, NTP who is a qualified expert. At KetoDiet we work with a team of health professionals to ensure accurate and up-to-date information. You can find out more on the About us page.

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