The carnivore diet, an extreme nutritional approach that eliminates all plant-based foods, has sparked considerable interest and debate. This diet centers entirely on meat, fish, eggs, and, in some cases, limited dairy. Proponents of the carnivore diet report various benefits, including improved energy levels, enhanced mental clarity, reduced inflammation, and weight loss. They argue that cutting out carbohydrates and plant-based foods can stabilize blood sugar and reduce inflammatory responses. However, the diet's restrictive nature raises concerns among health professionals regarding its long-term sustainability and potential health risks.
Understanding the Carnivore Diet
The carnivore diet is a version of the ketogenic diet, which shifts the body into ketosis, a metabolic state where fat becomes the primary energy source instead of carbohydrates. Unlike the standard ketogenic diet, which permits some plant-based foods, the carnivore diet eliminates all carbohydrates and fiber sources. This diet primarily consists of beef, pork, chicken, fish, eggs, organ meats, and some dairy products like cheese and heavy cream.
Historical and Evolutionary Context
Advocates of the carnivore diet often suggest that humans are evolved to consume a predominantly animal-based diet, reflecting the dietary habits of our ancestors. This perspective aligns with the idea that early humans relied heavily on hunting and consuming animal products for survival.
Potential Benefits of the Carnivore Diet
Supporters of the carnivore diet frequently cite several potential benefits, including increased energy, better mental clarity, and reduced joint pain. These claims are often supported by anecdotal evidence and personal experiences.
Weight Loss
A primary reason people adopt the carnivore diet is for weight loss. Since protein and fat are highly satiating, individuals often eat fewer calories overall. Research on low-carb, high-protein diets suggests that consuming 0.4-0.6 grams of protein per pound of body weight per day can significantly enhance weight loss compared to diets with lower protein intake.
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Blood Sugar Control
Individuals with diabetes have reported positive effects on the carnivore diet. In a survey, individuals with diabetes saw an average reduction of 0.4% in their HbA1c levels, indicating better blood sugar control. The elimination of processed carbohydrates and sugars can lead to more stable blood glucose levels.
Inflammation Reduction
Many carnivore diet followers report relief from inflammation-related conditions, including autoimmune disorders, allergies, and skin issues. About 60% of surveyed individuals began the diet to address these concerns, and many reported symptom improvements. Since the diet eliminates processed carbohydrates, sugar, and plant-based irritants, some people may experience a reduction in inflammatory responses.
Mental Health Benefits
Some studies connect meat consumption to lower rates of depression and anxiety. Many also talk of achieving greater mental clarity while on a carnivore diet.
Risks and Concerns of the Carnivore Diet
While the carnivore diet has passionate supporters, health professionals express concerns about its long-term effects. Eliminating fruits, vegetables, and whole grains removes essential nutrients, including fiber, vitamin C, folate, and antioxidants.
Nutrient Deficiencies
Eating only meat and animal-based products can lead to nutritional deficiencies. Different foods offer different vitamins and nutrients. Eating a variety of foods helps your body get the nutrients it needs to be at its best. Fiber is crucial for gut health, and a lack of it can lead to constipation, microbiome imbalances, and poor digestion. Interestingly, some individuals report diarrhea instead of constipation, likely due to shifts in gut bacteria. While organ meats provide many nutrients absent in muscle meat, few people regularly consume them.
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Heart Health
A major concern with the carnivore diet is its effect on heart health. The diet is high in saturated fat and cholesterol, which may raise LDL (bad) cholesterol levels. The survey of 2,029 carnivore diet followers found that their median LDL levels were 172 mg/dL, a significant increase that could contribute to cardiovascular disease risk. While some individuals see improvements in triglycerides and HDL (good) cholesterol, long-term data on heart health risks is lacking.
Kidney Strain
High-protein diets can strain kidney function, especially in individuals with preexisting kidney disease. Eating a diet high in animal protein can place added stress on your kidneys, which may affect their long-term filtering function. Eating more meat also may contribute to kidney stone formation.
Hormone Imbalance
A lesser-known risk of the carnivore diet is its potential effect on hormone balance. Since the diet eliminates carbohydrates completely, it can lower thyroid hormone levels, which play a key role in metabolism and energy production. Research shows that low-carb diets may reduce T3, the active thyroid hormone, leading to fatigue, sluggishness, and difficulty maintaining body temperature. Additionally, women following extremely low-carb diets have reported irregular menstrual cycles, likely due to hormonal shifts that impact reproductive health. Another concern is cortisol, the body’s primary stress hormone, which may increase when carbohydrates are too low. Chronically elevated cortisol can lead to sleep disturbances, anxiety, and even muscle loss over time.
Mental Health and the Carnivore Diet: Exploring the Connection
Emerging evidence suggests a potential link between the carnivore diet and improvements in mental health conditions. This connection warrants further investigation, particularly in the context of serious mental illnesses.
The Gut-Brain Axis
Toxins from foods can affect the brain directly through the vagus nerve, which connects the gut to the brain. They can also affect the brain indirectly through immune mediators like cytokines. The microbiome can send messages to the brain about what's happening in your gut.
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Nutrient Availability and Brain Function
Nutrient deficiency is a good place to start, definitely a root cause of mental illness. The brain is made of mostly fat, about two-thirds fat, and contains lots of protein, cholesterol, and a tiny bit of carbohydrate. Then there are the micronutrients, the vitamins, and minerals, because the brain is an energy hog. Macronutrient quality affects micronutrient availability. If you're getting your vitamins and minerals from the wrong place, they may not be as effective.
Inflammation and Oxidation
Inflammation and oxidation are well-established root causes of various mental illnesses. We often think of mental illnesses in terms of neurotransmitter imbalances, like problems with serotonin or dopamine. However, other neurotransmitters like glutamate and GABA are also crucial.
The Kynurenine Pathway
Under stress or oxidation, which can be caused by modern diets rich in refined carbohydrates and seed oils, the kynurenine pathway is altered, leading to neurotransmitter imbalances. This can't be fixed with medication alone.
Insulin Resistance
Eating the wrong way can lead to insulin resistance, which is emerging as a potential factor in mental health disorders.
Case Studies and Research Findings
Several case studies and research findings suggest potential benefits of the carnivore diet for mental health. However, it’s important to note that much of the evidence is anecdotal, and rigorous scientific studies are needed to confirm these findings.
Retrospective Case Report: Schizophrenia in Remission
This retrospective case report presents the use of a carnivore ketogenic diet by a subject with schizophrenia, supported by a nutritional therapy practitioner, resulting in remission. The narrative describes how ketogenic metabolic therapy can be implemented and optimized in difficult socio-economic circumstances, something not previously reported in the literature. Compliance with diet is reported using glucose and ketone blood markers.
Study on Meat Consumption and Mental Health
In this meta-analysis, we examined the quantitative relation between meat consumption or avoidance, depression, and anxiety. In June 2020, we searched five online databases for primary studies examining differences in depression and anxiety between meat abstainers and meat consumers that offered a clear (dichotomous) distinction between these groups. Twenty studies met the selection criteria representing 171,802 participants with 157,778 meat consumers and 13,259 meat abstainers. We calculated the magnitude of the effect between meat consumers and meat abstainers with bias correction (Hedges's g effect size) where higher and positive scores reflect better outcomes for meat consumers. Meat consumption was associated with lower depression and lower anxiety compared to meat abstention. Compared to vegans, meat consumers experienced both lower depression and anxiety. The analysis also showed that the more rigorous the study, the more positive and consistent the relation between meat consumption and better mental health.
Pilot Study on Ketogenic Diet and Mental Illness
Now, a pilot study led by Stanford Medicine researchers has found that a ketogenic diet not only restores metabolic health in these patients as they continue their medications, but it further improves their psychiatric conditions. In the four-month pilot trial, Sethi's team followed 21 adult participants who were diagnosed with schizophrenia or bipolar disorder, taking antipsychotic medications, and had a metabolic abnormality - such as weight gain, insulin resistance, hypertriglyceridemia, dyslipidemia or impaired glucose tolerance. Before the trial, 29% of the participants met the criteria for metabolic syndrome. "We're seeing huge changes," Sethi said. "Even if you're on antipsychotic drugs, we can still reverse the obesity, the metabolic syndrome, the insulin resistance. The psychiatric benefits were also striking. On average, the participants improved 31% on a psychiatrist rating of mental illness known as the clinical global impressions scale, with three-quarters of the group showing clinically meaningful improvement. "The participants reported improvements in their energy, sleep, mood and quality of life," Sethi said.
A Detailed Case Study: Schizophrenia in Remission with Carnivore Ketogenic Diet
The subject was a 32-year-old male who was first diagnosed with schizophrenia 3 years previously when he developed psychotic behaviors. He first consulted the nutritional therapy practitioner after his recent discharge from a rehabilitation hospital. He was taking prescribed medication including amisulpride 600 mg, mitrazapine 40 mg and propanalol 80 mg. Over the past four years he had experienced mood instability along with paranoid delusions and suicidal thoughts. The conventional treatment did not fully resolve his symptoms, and his experience of the mental health service was not positive. The trigger for the onset of mental illness included the death of a close relative which was traumatic and unexpected.
Initial Steps and Dietary Adjustments
The subject discovered the ketogenic diet when he read a self-help book during one of his early episodes living in a homeless shelter where it was suggested strategy to help improve your life. He decided to try a ketogenic diet simply to try and change his life, not with any expectation it would help his mental health. In the homeless shelter he had his own room where he was able to have a portable grill and minifridge and he adopted a carnivore ketogenic style of eating. However, at this stage he followed advice which allowed him to have ‘cheat days’ and on these days, he would eat large amounts of chocolate and other high sugar foods. He decided to pursue ketogenic metabolic therapy as an alternative treatment as soon as he was able to. Whilst in acute hospital settings it was impossible to do so, however his last hospital placement was a rehabilitation facility where residents could cook for themselves. He was able to restart a ketogenic diet successfully eating foods like eggs, with some vegetables and fatty meat. On his discharge from hospital, he contacted a nutritional therapy practitioner who specialized in ketogenic metabolic therapy for mental illness with the aim of optimising his diet. He wanted help to get his psychiatrist on board with using KMT as a treatment to help him reduce his medication. At initial consultation the subject’s glucose and ketones levels were analyzed as well as his diet which was now 100% carnivore. His blood glucose and ketone readings were fluctuating greatly so the aim was to stabilize his glucose levels and optimize his ketones in the therapeutic range.
Dietary Plan and Monitoring
The nutritional therapy practitioner suggested that he needed to eat a minimum of two meals a day to get sufficient protein and energy and gave him specific examples of the amount of meat and fat he needed to consume to stay in stable ketosis. He was advised to eat a 2:1 ratio of fat to protein (there were no carbohydrates as it was a meat and fat only diet). An example of daily meal plan with two meals a day including at least 69 g of protein. Meal suggestions included: a 226 g rib eye steak (43 g protein and 45 g fat) plus an addition 41 g of fat or 200 g of 20% fat beef mince (34 g protein and 40 g fat) plus another 28 g of fat. It was suggested that he stop supplementing with MCT oil and recommended to drink more water and add a little salt to his food. The subject tested his ketone/glucose levels twice a day, once in the morning before his first meal of the day and a second time before dinner, 3 h after the last meal. He was recommended to aim for his ketones to be between 2 and 4 mmol/L and no higher than 5 mmol/L. Compliance with the KMT was monitored using a glucose and ketone blood finger prick testing. Within a couple of days, the subject stabilized his readings with glucose remaining between 4 mmol/L and 6 mmol/L and ketones at between 3.0 mmol/L and 5.0 mmol/L. The subject’s continued cannabis use resulted in him becoming homeless again, but not due to a psychotic episode, as a result he cut back his cannabis use and focused on remaining mentally stable sustaining a steady state of ketosis.
Positive Outcomes and Medication Tapering
The subject was informed in late October 2024 that his mental health team noted his schizophrenia was in remission. He has had no psychotic episodes since he started the ketogenic diet on his discharge from hospital, a period of over nine months. He has come off all his psychiatric medications and remains stable. The subject has stayed in steady nutritional ketosis for several months with 100% compliance. This is confirmed by his ketone results and remain between 1.0 and 5 mmol/L but mostly within the 3 to 4 mmol/L level.
Practical Considerations and Recommendations
For those struggling with specific health conditions like metabolic disorders or autoimmune symptoms, short-term experimentation with the carnivore diet may offer benefits. The elimination of processed foods and sugars can improve blood sugar levels and reduce inflammation for some individuals. However, long-term sustainability remains a challenge.
Consulting Healthcare Professionals
If you are considering a dietary change, consult a healthcare professional. Nutrition is highly individualized, and what works for one person may not be beneficial for another. It is very important to consult with your prescribing clinician before embarking on any low-carbohydrate diet.
Balanced Approach
Health professionals generally recommend a more balanced approach. If weight loss or blood sugar control is the goal, a modified low-carb diet that includes nutrient-dense vegetables and healthy fats may offer similar benefits with fewer risks. Focus on filling your plate with a range of whole foods like fruits, vegetables, grains and lean meats. There may be some benefit in limiting carbs, especially simple carbs high in added sugar (like white bread and baked goods). But it’s not ideal for your body to cut out all carbs. The key is moderation.