The controversial carnivore diet has attracted a lot of attention in recent years. Its proponents claim that it’s the cure for all sorts of conditions – but how? What does the evidence say? Read on for a dive into the potential benefits of the carnivore diet.

What is the Carnivore Diet?

You may have landed here from one of our other posts on the carnivore diet:

If so, then you know that the carnivore diet is exactly what it sounds like: a diet of only meat. So far, we’ve discussed a lot of risks and pitfalls associated with cutting plant foods out entirely – but are there benefits as well?

People who eat a carnivore diet tell stories of mysterious diseases suddenly resolving themselves. They say that they’ve lost weight, that their brain fog is gone, that their athletic performance improved. Anecdotes abound; scientific evidence is lacking. Let’s look at some of the big claims from carnivores and see whether the science backs them up.

Snapshot

Eliminates potential plant-based irritants such as gluten & lectins

High in protein

Devoid of sugar and processed foods

Claims of weight loss

High risk of nutrient deficiencies

Doesn’t contain healthy plant compounds like polyphenols & fiber

May result in lower brain serotonin

Increases oxidative stress

May dysregulate the gut microbiome

Large carbon footprint

Expensive & inaccessible to many

Claims from Carnivores vs. Scientific Evidence

So, what’s the deal? Why do this? The carnivore diet is not well researched. As a result, a lot of people start this diet after hearing anecdotal reports of health benefits and life improvement. We’ve collected some of the most common claims and dug into the science to see what might be behind people’s experiences.

Because of the lack of research, most of the claims made by proponents of the carnivore diet are based on related or tangential studies on diets that have things in common with the carnivore diet, like low-carb or ketogenic diets. While these comparisons may have some value, they should not be used to make claims about the carnivore diet. Clinical trials on meat-only diets are required to determine whether carnivory is actually helpful for any of these health purposes.

Most doctors will not recommend a carnivore diet because of its significant drawbacks and deficiencies. If you have your heart set on switching to this diet, make sure to work with a doctor or nutritionist to avoid any adverse effects, nutrient deficiencies, or other complications.

1) Brain Function

Some people claim that humans are “meant” to eat meat because when our ancestors started eating meat, the extra energy and protein helped them get bigger, faster, and smarter very quickly. This much is true: the transition from a plant-only diet to an omnivorous diet coincided with a massive expansion in brain size. However, most researchers agree that it was actually the increased energy from fat, not anything else about meat-eating, that facilitated the increase in brain size [1, 2].

Anecdotal Claims

Many people who eat a carnivore diet claim to have reduced brain fog and improved cognitive function. They describe mental clarity and a sense of calm that was beyond their reach when eating carbohydrates.

The Evidence

Cognitive Function

According to one study of healthy men, increasing meat protein and decreasing carbohydrate intake improved reaction time [3].

Red meat intake increased branched-chain amino acids (BCAA) and phenylalanine in the blood of healthy men. BCAA in the brain may reduce fatigue; phenylalanine is a precursor to dopamine and norepinephrine [3].

According to a Chinese study, children who eat meat are more likely to maintain cognitive function later on in life. In healthy Korean children and teenagers, those who ate more meat and poultry had better scores on some cognitive tests [4, 5].

One study investigated the relationship between diet and dementia in underdeveloped parts of China. They found two dietary patterns correlated with lower rates of cognitive decline in older people: one based on mushrooms, vegetables, and fruits, and the other based on meat and soy [6].

Note that none of these studies used a zero carb, all-meat carnivore diet. They simply show a correlation between fresh meat intake and cognitive function. Furthermore, these claims are still controversial: other studies associated lower meat intake with a reduced risk of dementia [7].

No clinical trials have directly investigated any link between cognition and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat improves brain function.

Autism

One of the more interesting claims about the carnivore diet is that it can “cure” autism. Any such claim should be examined with extreme skepticism, and no clinical or even animal studies have been conducted to begin investigating whether it could be true. Instead, proponents point to one of two related claims as evidence:

The carnivore diet includes components that reduce symptoms of autism. The carnivore diet excludes components that produce or worsen symptoms of autism.

Could these related (but less dramatic) statements be true?

Included Foods that Reduce Symptoms

Meat contains high levels of cysteine, an amino acid that has been linked to reduced symptoms in autism. N-acetylcysteine (NAC), which mainly acts by releasing cysteine, reduced or resolved irritability associated with autism in multiple trials. Because everything eaten in a carnivore diet contains high levels of cysteine, this diet is probably much higher in cysteine than the average [8, 9, 10, 11].

Meat also contains high levels of carnitine. One study found that children with autism have lower carnitine levels and another found that carnitine supplements reduce symptoms compared to the placebo [12].

Increased intake of omega-3 fatty acids has also improved symptoms of autism, though some people responded better than others to supplementation. Oily fish (like salmon and sardines) are rich in omega-3 fatty acids [13, 14, 15].

Zinc, which is abundant in meat, can increase regulatory T cells (Tregs) and benefit people with autoimmunity. Zinc supplements have even improved symptoms in some (but not all) people with autism [16, 17, 18, 19, 20].

Excluded Foods that Worsen Symptoms

Elimination diets have helped some people with autism as well. Specifically, diets that exclude casein and gluten improved symptoms in autistic people who also have gastrointestinal troubles. People with autism tend to have elevated antibodies against casein, gliadin, and ovalbumin, protein components of milk, gluten, and eggs, respectively [21, 22, 23].

Some people with autism may have autoimmunity triggered by milk, wheat, and egg proteins. Their antibodies against these proteins can also react against their own neural tissues. According to some researchers, this secondary reaction may promote some of the symptoms of autism [23, 24].

Mixed Microbiome Influence

Gut flora composition also influences the autistic brain. People with autism tend to have more Clostridia, Bacteroides and Desulfovibrio, bacteria that produce propionic acid (PPA) and acetic acid. They also have less of the bacteria that produce butyric acid (a form of butyrate). PPA has been linked to autistic symptoms in rats [25, 26, 27, 28].

Animal fat and protein promote the growth of Clostridia and Bacteroides. Thus, the effect of a carnivore diet on the symptoms of autism may be mixed [25, 26, 27].

Note: increased intake of cheap, industrially-farmed poultry has been linked to autism. The precise cause of this correlation has not been established, and broader evidence does not support any claim that poultry causes autism [29].

No clinical trials have directly investigated any link between autism and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat reduces autism symptoms.

OCD

People with obsessive-compulsive disorder, or OCD, have increased glutamate brain activity. Glutamate is one of the most important neurotransmitters in the body, but its overactivity can cause neurological disorders and increase the sensation of pain [30, 31, 32, 33].

Savory foods like parmesan cheese and soy sauce contain high levels of glutamate. Plant proteins contain as much as 40% glutamate, while animal proteins contain 11-22%. Glutamate is also added to food as monosodium glutamate or MSG [34, 35].

Carnivore diets may restrict dietary glutamate, as long as they don’t include canned meat, processed meat, or preserved seafood [34, 35].

On the other hand, very little dietary glutamate reaches the blood and the brain. The evidence that dietary glutamate could worsen OCD symptoms is limited to case studies [36, 34, 35, 37, 31].

OCD (like autism), has been improved by increasing dietary cysteine [38, 39].

Non-celiac gluten sensitivity has been linked to multiple psychiatric conditions, including OCD, but the evidence is weak, and most researchers doubt that any such link is causal. Most likely, gluten sensitivity does not cause psychiatric conditions [40].

No clinical trials have directly investigated any link between OCD and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat improves OCD symptoms.

Schizophrenia

Non-celiac gluten sensitivity has also been linked to schizophrenia. Some researchers refer to “gluten psychosis,” a set of psychotic symptoms that may appear after a sensitive person eats gluten. In one case study, a 14-year-old girl had vivid, complex, sometimes terrifying hallucinations despite normal blood tests. Cutting gluten out of her diet completely resolved her symptoms [40, 24, 41].

Unfortunately, the evidence is limited to a single case study, which has very little scientific value. Furthermore, this single case study was about cutting out gluten, not eating only meat. There is no evidence to suggest that the carnivore diet could improve schizophrenia symptoms.

ADHD

Symptoms of attention deficit hyperactivity disorder (ADHD) tend to be worse in people who are deficient in certain nutrients, including zinc, iron, omega-3 fatty acids, and the amino acid methionine. All of these are plentiful in meat and fish [42, 43, 44, 45].

However, no studies have investigated the effect of eating only meat on people with ADHD. There is, therefore, no good evidence for any claim that carnivory improves ADHD symptoms.

Anxiety & Depression

The relationship between meat, anxiety, and depression is poorly understood. Some studies have linked higher red meat intake with rates of depression; others have correlated vegetarianism with depression. All of these studies have been limited; some don’t differentiate between processed and unprocessed meat, for example [46, 47].

This distinction is probably extremely important. Red meat intake, as part of a “traditional” non-Western diet, appears protective against anxiety and depression up to about 57 g per day. Above that point, red meat correlates with an increased risk of mental illness [48].

On the other hand, a potential association has been established between gluten and psychological conditions. Non-celiac gluten sensitivity is also linked with anxiety and depression [40, 49].

Vitamin B12 is also very important for managing mental health. In one study of people with both depression and low vitamin B12, supplementation significantly reduced symptoms. Red meat is high in B12 [50, 51].

No clinical trials have directly investigated any link between anxiety, depression, and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat improves mental health.

2) Food Sensitivity Triggers

Most people who eat a carnivore diet are likely to say that they eat this way to avoid the “toxins” or anti-nutrients in plant matter. They point to compounds like gluten, oxalates, lectins, histamine, and other potentially inflammatory compounds found in plant-based foods, which may cause serious illness in people who are sensitive to them [52, 53, 54].

Anecdotal Claims

Many people have said that their previous omnivorous diets made them feel brain-fogged, fatigued, or downright ill. After switching to a carnivore diet, they had more energy and felt healthier, which they say is because of decreased inflammation.

People say that their arthritis, Hashimoto’s disease, and other autoimmune disorders improved on a carnivore diet.

The Evidence

SelfDecode has several articles on how some plant-based compounds, such as lectins, can cause inflammation and autoimmunity. Some of the most likely culprits include:

Lectins [55]

Histamine [56]

Gluten [57]

Saponins [58]

Salicylates [59, 60]

Sulfites [61, 62]

MSG (monosodium glutamate) [63]

Completely eliminating all plant foods and only eating meat is not the only way to avoid potential irritants. Doctors routinely use elimination and reintroduction diets to manage diseases like irritable bowel syndrome and esophagus inflammation (eosinophilic esophagitis) [64, 65].

The benefit of reintroducing some plant foods is that you will then have access to all of the nutrients and phytochemicals in those plants [66].

Autoimmunity

As described above, some people experience autoimmunity which may be triggered by milk, wheat, and egg proteins. According to some researchers, antibodies against these proteins can cross-react, attacking brain tissues, which can potentially cause brain fog and other neurological symptoms [23, 24].

Zinc, which is high in meat, can increase regulatory T cells (Tregs) and prevent autoimmunity. Zinc supplements have even improved symptoms in some (but not all) people with autism [16, 17, 18].

B vitamins, which are plentiful in meat, tend to improve the symptoms of lupus, an autoimmune condition. Vitamin B6, in particular, may suppress inflammation and support correct immune function in people with lupus [67, 68].

By contrast, healthy diets low in red meat (like the Mediterranean diet) tend to improve autoimmune conditions like rheumatoid arthritis. Similar to the carnivore diet, they help by reducing or eliminating autoimmune-triggering proteins. But they are also plentiful in anti-inflammatory foods the carnivore diet lacks, such as olive oil [69, 70].

No clinical trials have directly investigated any link between autoimmunity and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat prevents or reverses autoimmune disease.

3) Diseases

Anecdotal Claims

Websites promoting the carnivore diet are full of people’s stories about diseases they completely cured by eating nothing but meat. In different forums and comment sections, people have claimed that the carnivore diet cured:

Arthritis

Autism

Cancer

Heart disease

Diabetes

Endometriosis

Epilepsy

Multiple sclerosis

Polycystic ovarian syndrome

…and more.

The Evidence

Unfortunately, modern research has not investigated the carnivore diet’s potential to manage many diseases. One Hungarian research group has conducted multiple case studies, but no trials with multiple subjects or any type of control.

According to this research group, the “paleolithic ketogenic diet,” an all-meat, high-fat diet, has successfully managed childhood absence epilepsy and type 1 diabetes, among other diseases. This diet emphasizes a high fat to protein ratio of between 2:1 and 4:1 in order to induce ketosis [71, 72].

Increased non-processed red meat intake was associated with reduced markers of multiple sclerosis risk [73].

This is all considered to be very low-quality evidence, however. There isn’t nearly enough evidence to support any claim that the carnivore diet prevented or cured any disease.

Female Reproductive Disorders

Endometriosis and polycystic ovarian syndrome (PCOS) are the two most common female reproductive disorders. In endometriosis, uterine tissue grows outside of the uterus, causing pain and reducing fertility. In PCOS, excess androgens (like testosterone) cause ovarian cysts, which reduces fertility [74, 75].

Red meat intake is actually linked to increased rates of endometriosis, while poultry, fish, shellfish, and eggs have no effect. Some researchers even call red meat one of the major culprits behind endometriosis. Meanwhile, higher fruit intake (especially of citrus fruit containing beta-cryptoxanthin) was linked to reduced rates of endometriosis [74, 76, 77].

But there’s a catch: cruciferous vegetables, which are otherwise considered extremely healthy, were linked to a 13% higher rate of endometriosis [78].

In theory, the increased D and B vitamins, omega-3 fatty acids, and cysteine in a balanced carnivore diet could improve endometriosis, but the decreased antioxidant status could worsen it. No clinical studies confirm either of these, as no clinical studies have been done on the carnivore diet’s effect on women’s reproductive health [79, 80].

In PCOS, meanwhile, red meat intake is linked with infertility. Again, the increased vitamin D in fish may help. Beef, steak, pork chops, and chicken liver are also relatively rich in myo-inositol, which may help with PCOS symptoms; however, some fruits (especially cantaloupe and citrus), whole wheat, and many nuts and beans are much higher, so the carnivore diet won’t necessarily increase inositol [75, 81, 82, 82].

In one small study of 57 women, a high-protein, low-carbohydrate diet improved weight loss, glucose metabolism, and PCOS symptoms. The beneficial diet was intended to produce over 40% of energy from protein, about 30% from fat, and less than 30% from carbohydrates [83].

Overall, the observed relationship between meat and PCOS is not promising. This anecdotal benefit is not supported by the evidence.

No clinical trials have directly investigated any link between women’s reproductive health and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat improves fertility or prevents reproductive disorders.

Cancers

Red meat intake is believed to increase colorectal cancer risk. In a study of over 8000 Korean adults, higher red meat intake was associated with a higher overall risk of developing cancer [84, 85].

Furthermore, many people who claim that carnivory is good for cancer do so based on the assumption that the carnivore diet induces ketosis, which it very likely does not. See the section below on carnivory & ketosis for why.

With the exception of kidney cancers and some melanomas, ketogenic diets reduced tumors in almost all cancers tested in animal models, but the effect on humans is unknown [86].

Well-designed clinical studies would reveal if ketogenic carnivore diets can help control some cancers; some such trials are currently underway. According to early results, some cancers may respond well to ketosis, while others may worsen [87, 88].

There is currently not enough evidence to confidently claim that ketogenic diets can prevent or treat cancer; however, they may be useful in combination with conventional therapies [87, 88].

Do not attempt to treat cancer with a carnivore diet. Talk to your doctor about the potential of a ketogenic diet alongside other therapies.

No clinical trials have directly investigated any link between cancer and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat has any benefit in cancer.

Carnivory & Ketosis

Some people claim that the carnivore diet is beneficial because (among other things) it induces ketosis, forcing the body to burn fat for energy. However, there is no evidence that the carnivore diet induces ketosis, and furthermore, about half of ingested protein, by mass, is converted to glucose for energy [89].

Therefore, the benefits of ketogenic diets cannot be applied to the carnivore diet.

A recent guide to medical ketogenic diets recommends that the diet be 55-60% fats, 30-35% protein, and 5-10% carbohydrates. Carbs should be kept under 50 g for every 2000 calories consumed. Other guides recommend a fat to protein ratio of 4:1 or 3:1. The vast majority of people eating a carnivore diet will not fall into these ratios; they will generally be consuming less fat and much more protein [90, 91].

The carnivore diet is extremely unlikely to induce ketosis because about half of ingested protein is converted to glucose.

4) Heart Health

Anecdotal Claims

Some people claim that the carnivore diet got their heart rate, blood pressure, and cholesterol way down. A few even say that eating only meat got rid of the plaques in their blood vessels and drastically reduced their risk of heart attack, making improvements that even medication could not.

These are huge claims that are broadly not supported by the evidence.

The Evidence

Saturated fats, which are plentiful in meat, were long considered a risk factor for heart health – until, in 2015, a meta-analysis showed no correlation between saturated fat intake and cardiovascular disease [92, 93].

Bad News

Again, however, there is controversy: eating red meat is associated with increased trimethylamine N-oxide (TMAO). TMAO is believed to increase the risk of plaques in the blood vessels, which in turn can cause a heart attack or stroke [94].

Fatty and preserved red meats have also been associated with cardiovascular disease, with preserved or processed meat carrying the strongest association [95, 96].

No clinical trials have directly investigated any link between heart disease and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat has any benefit in cardiovascular health.

5) Digestive & Kidney Health

Anecdotal Claims

Some people have claimed that the carnivore diet got rid of their kidney stones, improved diverticulitis, and resolved constipation. Many people also claim that their irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD) went away on the carnivore diet.

The Evidence

When mineral levels are too high for the kidneys to process, kidney stones can form. One of the risk factors for stones is oxalate intake; oxalates are abundant in foods like nuts, seeds, leafy greens, rhubarb, soy, and wheat bran. On the other hand, diets that are very high in protein may also stress the kidneys and increase the likelihood of stone formation [97, 98, 99].

Diverticula are small pouches that sometimes form in the lining of the intestine. These can become inflamed, causing a painful condition called diverticulitis. Diets that are low in fiber and high in red meat are believed to increase the risk of diverticulitis. In one study of 764 cases of diverticulitis, poultry and fish was not associated with the disease; red meat, however, was [100, 101, 102].

Dietary fiber is generally considered to improve the passage of stool and prevent constipation. However, low-fiber diets can resolve constipation of unknown cause. Furthermore, decreasing or eliminating certain carbohydrates like FODMAPs may resolve symptoms of irritable bowel syndrome (IBS) [103, 104].

Fiber, Gut Flora & IBD

Our diets determine what kind of bacteria live in our intestines and help digest our food. High fiber intake promotes the growth of bacteria that ferment carbohydrates into short-chain fatty acids (SCFAs). High animal fat and protein intake reduces the overall population of gut bacteria and promotes Bacteroides and Clostridia [27].

Low levels of Bacteroides (which thrive on animal fat and protein) are linked to increased rates of Crohn’s disease and ulcerative colitis (types of inflammatory bowel disease). However, gut bacteria can also produce harmful waste products like trimethylamine-N-oxide (TMAO) when they digest meat [105, 106].

Finally, the amino acid glutamine protects the tight junctions of the intestinal wall and may prevent “leaky gut.” Beef has more glutamine by weight than many other proteins, including tofu, egg, and milk [107, 108, 109].

Glutamine has shown promise as a supplement for people with irritable bowel syndrome (IBS). In one study, 15 g of glutamine per day for 8 weeks improved symptoms of diarrhea type IBS. However, the placebo in this trial was whey powder, which could have produced more symptoms in the placebo group and exaggerated the results [110, 111].

No clinical trials have directly investigated any link between digestive health and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat has any benefit for the gut.

6) Weight Management

Anecdotal Claims

Many people online have stories about weight loss after switching to a carnivore diet. Some show off impressive “before and after” photos demonstrating the new, slimmed-down figures that they attribute to eating all meat.

The Evidence

Increased red meat intake has been linked to increased inflammation in people who already have an excess of fat. However, this effect has only been studied in people eating omnivorous diets; we don’t actually know how a carnivore diet interacts with fat tissues [112].

If a well-designed carnivore diet is ketogenic, then some evidence suggests that it may be a useful weight-loss tool. Ketogenic diets promote weight loss through improved fat metabolism. In multiple studies, people on ketogenic diets lost more weight faster than other weight-loss diets. Importantly, people on ketogenic diets lost much more weight than people on low-fat diets [113, 90, 114].

If you want to use ketosis to manage your weight, we strongly recommend working with a licensed nutritionist to that end. The carnivore diet is too high in protein and low in fat to induce ketosis, and a professional can help find the right solution for you.

Low-carb diets have been a weight loss strategy since the mid-1800s. According to one approach, low-carb diets work by decreasing insulin production. This, in turn, would prevent fat storage and promote weight loss [115, 116].

Some studies even suggest that low-carb diets increase the amount of energy burned by 200-300 calories, given the same number of calories is consumed. However, this result is controversial [115, 117].

Sugar is another factor. Many processed foods have refined sugars added during production, which may promote metabolic disease and weight gain. A true carnivore diet has no added sugar whatsoever [118].

Finally, protein increases satiety: that is, it helps you feel like you’ve eaten enough food. When we feel sated, we consume fewer calories. High-protein diets have improved body composition and helped people lose weight in some clinical studies [119, 120, 121].

No clinical trials have directly investigated any link between weight loss and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat has any benefit for weight.

7) Decreases Inflammation

Anecdotal Claims

A lot of people say they were drawn to the carnivore diet because they had arthritis and joint pain, which advocates said would disappear if they cut all plant foods out. People share stories online of arthritis, diverticulitis, asthma, and other inflammatory diseases completely disappearing after they switched to eating all meat.

The Evidence

According to most research, red and processed meats are typically associated with increased inflammatory markers. However, these studies don’t tend to differentiate between beef, pork, lamb, and other red meats; processed meat is also far worse than fresh in every case. Also, the studies don’t differentiate between the quality of meat or its preparation (such as grilled vs. non-grilled) [112, 122].

As mentioned above, a well-designed carnivore diet may be able to induce ketosis. Ketogenic diets (and low-carb, high-fat diets in general) tend to be anti-inflammatory: in one study of overweight adults, a very-low-carb ketogenic diet (VLCKD) reduced oxidative stress and inflammation over twelve weeks [123, 124].

Ketogenic diets are well known to reduce the symptoms of epilepsy, probably by reducing inflammation. In rats, ketogenic diets also reduced markers of pain and inflammation [125].

By contrast, diets high in carbohydrates increase inflammation [124].

Oily fish like salmon and sardines are rich in anti-inflammatory omega-3 fatty acids. Some meats, like pork, may even have anti-inflammatory effects, though researchers have only demonstrated these effects in cells; these studies may have no bearing whatsoever on the effect of pork when consumed [126, 15, 127].

In other words, it’s complicated, and there’s plenty of conflicting evidence. Scientists have not reached a consensus about how an all-meat diet might affect inflammation. When people switch to the carnivore diet and their inflammation goes away, it may have more to do with the elimination of certain plant compounds (and, if applicable, with ketosis) than with the meat itself.

No clinical trials have directly investigated any link between inflammatory conditions and the carnivore diet. There is therefore no evidence to support the claim that eating only meat has any anti-inflammatory benefit.

8) Athletic Performance

Anecdotal Claims

Bodybuilders, strength trainers, and other athletes seem to be drawn to the carnivore diet. Some people claim that eating only meat increases muscle strength and endurance, increases lean mass and improves mental performance during high-intensity exercise.

The Evidence

Researchers have not investigated the effect of a carnivore diet on athletic performance. People on the carnivore diet regularly eat up to a kilogram of protein per day, which is much higher than in most formal studies. Your total protein intake depends on the type and amount of meat you eat [128].

That being said, strength-training athletes need a lot of high-quality protein every day to maintain muscle mass and power and to recover from performance or injury. Researchers recommend 1.4-2.4 g of protein per kg of body weight per day, or 127-218 g per day for a 200 lb athlete [129, 130].

Animal-based proteins provide all the essential amino acids and are digested more easily than plant-based proteins. Meat is high in vitamin B12, B6, and iron, which is especially important for female athletes who are at a greater risk of deficiency. Lastly, plant-based foods contain antinutrients (such as lectins and tannins) that reduce the absorption of proteins [129, 131].

In turn, athletes who ate meat gained more lean muscle mass than those who follow vegetarian diets, even when vegetarians include milk and eggs [129].

These benefits are not limited to athletes: in older people eating omnivorous diets, higher red meat intake was linked with increased muscle mass and function [128, 132].

No clinical trials have directly investigated any link between athletic performance and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat has any benefit for physical performance.

9) Libido

Anecdotal Claims

Some people claim that the carnivore diet increased their libido, or at least restored it to “normal” levels following a drop due to medication or stress. Women and men have both reported this benefit to varying degrees.

Many carnivores assume (and subsequently claim) that the return of their libido was linked to increased levels of testosterone.

The Evidence

Conflicting evidence abounds on this point. In some studies, lower red meat intake is associated with erectile dysfunction. In others, the opposite. Some studies link red meat intake with poor reproductive health; however, fresh unprocessed red meat decreased sex hormone binding globulin (SHBG), which should increase free testosterone and increase libido. High-fat, low-fiber diets have also been linked to increased testosterone [133, 134, 135, 136, 137].

Processed meats are likely the worst offenders here, with a strong inverse association between processed meat intake and sperm count [135].

Sexual dysfunction is also more common in overweight and obese people; some people argue that if the carnivore diet helped these people lose weight, it may also have restored sexual function. In overweight men, weight loss increases total and free testosterone, sex hormone binding globulin, and sexual function [138, 139].

Finally, arginine supplements may improve erectile dysfunction in some men by boosting blood flow; meat and fish are rich in arginine [140, 141].

No clinical trials have directly investigated any link between libido and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat has any benefit for libido or fertility.

10) Growth & Development

Anecdotal Claims

Some carnivores advocate giving the diet to children and adolescents; some go as far as weaning their babies directly onto a carnivore diet when they’re done breastfeeding. They claim that their children are “big, strong, and smart.”

The Evidence

Meat is packed with nutrients like protein, iron, and B vitamins; these promote healthy growth and development in children and teenagers. In one British study, adolescents who ate red meat were at lower risk for nutrient deficiencies than those who didn’t [142].

In a study of over 3000 US babies and children growing up in low-income families, adequate meat intake was key to preventing stunting. Thus, most doctors recommend a balanced diet including meat early on, but it doesn’t mean that you should feed a carnivore diet to children [143].

Unless you are a trained nutritionist, or you have a trained nutritionist to advise you, we don’t recommend feeding only meat to your children. The risk of deficiencies (of nutrients mainly found in plants) is just too high, and there’s at least one documented case of an exclusively meat-eating child getting scurvy [144].

Meat is good for kids, but nutrient intake is even more important during growth and development than it is during adulthood. If your child needs a specialized diet for any reason, we strongly recommend working with your doctor to design it.

No clinical trials have directly investigated any link between growth, development, and the carnivore diet. There is, therefore, no evidence to support the claim that eating only meat has any benefit for a growing child.

11) Convenience

There are a lot of diets out there, all claiming to produce amazing health benefits and improvements to the quality of life. Most of these diets are complex and challenging, requiring pamphlets, websites, and even entire books to explain and direct. Mediterranean diet, Atkins diet, alkaline diet, macrobiotic diet: they’re difficult to understand, let alone maintain.

Advocates of the carnivore diet say there’s no simpler diet: after all, all you need to do is eat meat and drink water.

What the Science Says

Of course, it’s not actually that simple; not all meat is created equal, and our bodies still have nutrient requirements beyond what just meat can provide. As we explained in our post on potential nutrient deficiencies, a poorly-designed carnivore diet may be lacking in:

Check out our deficiency post to find out how you can get these important nutrients without breaking your carnivore diet. We also recommend working with a trained nutritionist or a doctor before you make significant changes to your diet. It’s a little extra work, but it’s worth it to maintain optimal health.

Possible Uses of Elimination Diets

The carnivore diet isn’t right for everyone, and many doctors recommend against it because of the risk of nutrient deficiencies and other problems. We strongly recommend consulting a doctor or a trained nutritionist before making such a dramatic change in diet.

Food Sensitivities

As described above, people can be sensitive to certain compounds that are common in plant foods. If you suspect that your health problems are caused by sensitivity to lectins, gluten, or other compounds, carnivory could be a good starting point for an elimination diet [52, 53, 54].

If you cut out all plant foods and your health problems resolve, consider reintroducing (or “challenging”) one potential plant-based trigger at a time. Figure out what does and does not cause inflammation in your body, and use that information to design your own diet. A trained nutritionist can help guide you through an elimination diet.

Who Should Avoid the Carnivore Diet?

This is not necessarily a comprehensive list of conditions in which a carnivore diet could be harmful. To avoid any adverse effects, talk to a doctor or trained nutritionist before making significant changes to your diet.

Chronic Kidney Disease

High-protein diets are considered dangerous for people with chronic kidney disease (CKD). Protein can increase pressure and filtration rate in the kidneys, leading to additional damage and accelerating the disease [99, 157, 158].

If you have or are at risk for CKD, the carnivore diet is probably not the way to go.

Pregnancy

Because of the lack of research and high risk of nutrient deficiencies, pregnant women should not eat a carnivore diet. Once high-quality studies have been conducted, trained nutritionists may be able to guide you through a healthy carnivorous diet while you are pregnant. However, we do not recommend doing this alone.

Limited Access to Organic Meat

Organic, grass-fed meat is expensive. As such, people of lower socioeconomic status have less access to it: the carnivore diet is, by definition, exclusive to people with enough money to buy large quantities of high-quality meat. If you don’t have reliable access to the best cuts of organic meat, the carnivore diet may not be feasible [159].

This is a big problem with healthy food options in general. Many of the foods that are best for our health are also the most expensive [160].

Good Health

If you’re in excellent health eating your current diet, there’s no reason to switch. Modern scientists haven’t investigated the effects of eating only meat; most case studies and anecdotal success stories are about resolving a problem like epilepsy or arthritis. If it ain’t broke, don’t fix it.

Warnings from Carnivores

Not everyone who starts the carnivore diet is happy with the results. Some have told horror stories.

Some people developed scurvy, and their teeth and hair started falling out. Others fell into depression and suffered powerful cravings for fruits, vegetables, and sugars. Thyroid problems, high cholesterol, and menstrual irregularities sometimes emerge after several months on the carnivore diet.

Many people who eat a carnivore diet are not extremely strict. They say that they eat a ketogenic diet or low carb high fat (LCHF) diet in social settings and eat only meat in the comfort of their home.

Strict adherents to the diet often describe nausea, vomiting, diarrhea, and severe fatigue after eating a piece of bread or fruit.

Limitations and Caveats

The biggest limitation of any discussion of a carnivorous diet is the lack of research on its effect on the human body. All of the studies on an animal-based diet were either very short (a few days), case studies of Antarctic explorers or victims of scurvy, or anthropological reviews of cultural practices (which always involve at least some plants).

Studies that last a few days can only tell you what the carnivore does over the course of a few days. In the longer term, poor nutrition may cause thyroid and hormonal problems, nutrient deficiencies, or even beneficial adaptations, but these are not well documented in the specific case of the carnivore diet.

Proponents of the carnivore diet claim that the human body’s nutritional requirements are different after several months of eating only meat, but there is little research to back them up.

Some case studies of Antarctic explorers suggest that human bodies can adapt to eating only (freshly killed, sometimes raw) meat over a long period of time. Other case studies of people with scurvy suggest that a truly healthy carnivore diet is almost impossible for the modern, city-dwelling person: vitamin C and other nutrients are hard to get from commercial meat and many organs are difficult to find, buy, and prepare properly.

A lot of people make a lot of claims about the carnivore diet. The landscape may be difficult to navigate; always check people’s claims against their sources to make sure you have the best information available.

The Final Word

Ultimately, there is no evidence to support the use of the carnivore diet for any of its purported benefits. While its proponents are passionate, the research simply does not exist – and furthermore, the studies that carnivores use to defend their claims are often not applicable or relevant.