The carnivore diet, a highly restrictive dietary approach consisting exclusively of animal-derived foods, has recently gained popularity. While proponents tout various health benefits, concerns have emerged regarding its potential impact on metabolic health, particularly in relation to hyperlipidemia and non-alcoholic fatty liver disease (NAFLD). This article examines the potential risks associated with the carnivore diet, focusing on its effects on lipid profiles, liver health, and overall cardiometabolic well-being.
The Carnivore Diet Conundrum
Recently, a new fad diet has taken the online world by storm: the carnivore diet. Urged on by celebrity adherents, thousands of people have made the decision to try it. The carnivore diet, if followed by a human, is a diet that is made up entirely of animal-derived foods. This means breakfasts of just bacon and eggs, with no toast or bagels; lunches made up of burger patties and cheese, with no tomato, lettuce or pickles; and dinners made up of roast beef with a side of salmon, with no potatos or rice. In recent years the carnivore diet has risen to prominence as a more extreme version of other diets, known as keto diets, that place the body into a state of ketosis by limiting the consumption of carbohydrates. Ketosis occurs when the body has used up all of its glucose and begins to break down fat instead.
The most vocal adherents to a carnivorous diet proclaim the many health benefits that they experienced after starting to eat primarily meat and animal products. They claim that they have less pain and generally improved bodily function. However, Joe Rogan, who adheres to a diet made up exclusively of meat and fruit every January, has been open about the gastrointestinal issues and diarrhea he experiences while following the diet. The human body is able to adapt and survive even when not provided with optimal nutrition. Whether humans can thrive on a carnivorous diet in the long term has not been settled through longitudinal research but everything that we know about human nutritional needs suggests that humans cannot survive healthily consuming a fully carnivorous diet. Meat does contain many of the nutrients necessary to stay healthy but it is severely lacking in others. Even if supplements are included as part of a carnivorous diet, consuming meat, especially red meat, has been tied to an increased risk of developing heart disease. The risk is especially prominent with the consumption of processed meat. Following a carnivorous diet also increases the likelihood of facing digestive issues. Fiber comes from plant sources, so if fruit, vegetables and grains aren’t making it onto your plate you’re likely to be deficient in fiber. There has been little research done to determine what kind of results people can expect from following a fully carnivorous diet. What has been done relies on self-reported surveys or other subjective methods of data collection. Through these and other firsthand accounts, adherents report generalized improvements to their health, similar to other anecdotes given by adherents of new diets.
Consuming a diet made up primarily of meat increases the likelihood of developing heart disease and high blood pressure. Meat is high in fat, cholesterol and, with processed meats, sodium. Fiber is a necessary part of our diet that comes purely from plant sources. Not consuming enough fiber has been linked to severe physical and mental health issues as well as diarrhea and indigestion. Eating a carnivore diet may come with serious consequences for the liver and kidneys, especially if they are already damaged, diseased, or stressed. A diet high in protein, especially animal-derived protein, can lead to hypertension which in turn may lead to several different kidney issues. Those already experiencing kidney issues are at greatest risk. Meanwhile, eating a large amount of animal protein can also lead to fatty liver disease, especially in those that are already overweight or elderly.
Dyslipidaemia and Dietary Habits
Dietary habits play a crucial role in long-term cardiometabolic outcomes. A recent review of 686 patients (mean age ~62.6±8 years) with dyslipidaemia and/or type 2 diabetes mellitus underscores the impact of dietary habits on long-term cardiometabolic outcomes. Notably, while more than half (56.8%) of these patients achieved adequate glycaemic control (HbA1c <7%), the majority were overweight or obese (BMI 31.8±7.25). In examining their eating patterns, the consumption of a balanced breakfast (p=0.001) and having two main meals (p=0.008) were positively correlated with better lipid and glycaemic control. Meanwhile, frequent intake of junk food (p=0.009), soft drinks (p=0.056), and sweets (p<0.001) negatively impacted metabolic and lipid parameters. Notably, those following a Mediterranean-like diet were found to have a lower prevalence of metabolic syndrome.
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Hyperlipidaemia in Carnivore Diet Adherents
One of the most striking clinical warnings comes from two young, otherwise healthy male patients who adopted a strict carnivore diet for a year. They presented with LDL-cholesterol levels exceeding 15 mmol/L (≈580 mg/dL)-a threshold typically suggestive of homozygous familial hypercholesterolemia. However, genetic testing revealed no familial hypercholesterolemia mutations, pointing instead to the dietary pattern itself as a potent driver of their dyslipidaemia. Detailed fractionation of lipoprotein profiles showed disproportionate elevations of VLDL and IDL, indicating severe hyperlipoproteinemia likely stemming from high levels of dietary saturated fat and cholesterol. Although liver fat remained low in these individuals (based on imaging), both displayed early indicators of atherosclerosis (increased carotid intima-media thickness). As GPs often manage lipid testing and initial patient counselling, it is essential to consider the carnivore diet as a potential cause of alarmingly high LDL-C in patients otherwise lacking a clear genetic aetiology.
The Link Between Meat Consumption and NAFLD
Non-alcoholic fatty liver disease (NAFLD) has been associated with meat consumption in cross-sectional studies. High consumption of red and/or processed meat (≥gender-specific median) was associated with a higher risk of NAFLD with elevated alanine aminotransferase (ALT) (OR = 3.75, 1.21-11.62, p = 0.022). Consistently high (in both baseline and follow-up evaluations) total meat consumption was associated with 2.55-fold (95% CI 1.27-5.12, p = 0.009) greater odds for new onset and/or persistence of NAFLD compared to consistently low meat consumption. A similar association was shown for consistently high consumption of red and/or processed meat (OR = 2.12, 95% CI 1.11-4.05, p = 0.022). Consistently high red and/or processed meat consumption was associated with 4.77-fold (95% CI 1.36-16.69, p = 0.014) greater odds for significant fibrosis compared to consistently low consumption.
Study Details
A prospective cohort study was conducted, including subjects who participated in a baseline metabolic and hepatic screening survey and were followed for at least five years. The baseline survey was conducted between the years 2010 and 2015, and the follow-up evaluation was carried out between the years 2017 and 2020. Exclusion criteria at both time points included the presence of hepatitis B surface antigen (HBsAg) or hepatitis C virus (HCV) antibodies, fatty liver suspected to be secondary to hepatotoxic drugs, inflammatory bowel disease, celiac disease, and/or excessive alcohol consumption (≥30 g/day (d) in men or ≥20 g/day in women). Subjects who reported an unreasonable caloric intake below or above the accepted range (in one or both of the evaluations) 800-4000 Kcal/day for men and 500-3500 Kcal/day for women-were also excluded.
In both baseline and follow-up evaluations, participants underwent fasting blood tests, liver ultrasound (US) and/or FibroScan, and a face-to-face interview based on a structured questionnaire assembled by the Israeli Ministry of Health for national surveys, including demographic details, health status, alcohol and coffee consumption, smoking, and physical activity habits. In addition, they completed a food frequency questionnaire (FFQ), including detailed questions regarding meat consumption. The participants were informed of their US or FibroScan and blood test results only after completing the questionnaires, so as to avoid reporting bias.
Fatty liver was evaluated at baseline by liver US in all patients, while at follow-up the liver US was available only to a subsample (due to availability limitations). FibroScan was available only at the follow-up evaluation. At the follow-up evaluation, one of two methods was used to detect NAFLD: (1) liver US using standardized uniform criteria, performed by the same operator and using the same equipment (EUB-8500 scanner Hitachi Medical Corporation, Tokyo, Japan) at both baseline and follow-up; or (2) controlled attenuation parameter (CAP) performed by the same operator and using the same equipment (FibroScan 502 Touch; Echosens, Paris, France), with a cutoff of ≥294 dB/m indicating fatty liver. Non-invasive assessment of liver fibrosis was performed by liver stiffness measurements (LSMs) using vibration-controlled transient elastography (VCTE), which has good diagnostic accuracy in the evaluation of fibrosis. The median of 10 measurements represented the LSM score. This was considered reliable only if at least 10 successful acquisitions were obtained and the interquartile range (IQR)-to-median ratio was ≤0.3. NAFLD patients with elevated alanine aminotransferase (ALT), which suggests hepatocellular injury, may have a higher inflammatory component. Therefore, we added to the outcomes a subgroup of NAFLD patients who also manifested elevated ALT. Elevated ALT was defined according to the American College of Gastroenterology (ACG)’s clinical guideline cutoffs: ALT > 33 IU/l for men and ALT > 25 IU/l for women. Persistent NAFLD with elevated ALT was defined as NAFLD diagnosis on imaging plus elevated ALT at both time points.
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The semi-quantitative FFQ-assembled by the Food and Nutrition Administration of the Ministry of Health, and tailored to the Israeli population-was composed of 117/183 (for baseline and follow-up evaluations, respectively; the differences stem mostly from detailed meat preparation methods in the follow-up evaluation) food items, including different meat types with specified serving sizes. We calculated meat consumption in grams (g) per day for each subject at the two time points. Meat types were categorized as previously described; a detailed list of meat variables is depicted in the Appendix (Table A1). High meat consumption was considered above the baseline and follow-up gender-specific medians, as detailed in Table A1. Changes in meat consumption were calculated through four categories: consumption below the gender-specific medians in both time points (consistently low), consumption above the gender-specific median at baseline and below the gender-specific median at follow-up (decreased), consumption below the gender-specific median at the baseline and above the gender-specific median at follow-up (increased), and consumption above the gender-specific median at both time points (consistently high).
Statistical analyses were performed using SPSS version 27 (IBM-SPSS Armonk, NY, USA). Continuous variables are presented as means ± SD. The independent samples t-test was used to test differences in continuous variables between the two groups of high and low meat consumption. Associations between nominal variables were tested by Pearson’s chi-squared test, and p for trend was calculated when appropriate. A multivariable logistic regression analysis was performed to test the adjusted association between meat intake and the incidence, persistence, and remission of NAFLD, adjusting for potential confounders (i.e., variables that are related to NAFLD, and which differed between the meat intake categories at baseline). For the outcomes “incidence of NAFLD” or “incidence of NAFLD with elevated ALT”, only subjects without these outcomes at the baseline survey were included. For the combined outcome of either “new onset or persistence” (the presence of outcome at both time points) of “NAFLD” or “NAFLD with elevated ALT”, the entire sample was included in the analysis. In this analysis, the comparison was made to subjects who had never had these outcomes, or had a remission of the outcome at the follow-up evaluation. The fully adjusted model includes both potential confounders (i.e., age, gender, energy, body mass index (BMI)) and potential mediators (i.e., protein and cholesterol intake). The odds ratio (OR) and 95% confidence interval (CI) are presented. A p-value ≤ 0.05 was considered statistically significant for all analyses.
Study Results
A total of 970 subjects participated in the baseline survey. Of those, 402 attended the follow-up evaluation. Nineteen subjects were excluded because of hepatotoxic drug use, secondary liver diseases, or other related medical conditions. Sixty-three subjects were excluded because of unreasonable caloric intake at either baseline or follow-up evaluation. Of the 320 subjects remaining, only 316 were assessed for NAFLD in the follow-up evaluation, and were included for analysis (101 subjects underwent the liver US, 236 underwent CAP). New onset or persistence of NAFLD was found in 34.50% (n = 109/316) of the sample. Of those without NAFLD at baseline, 18.20% (n = 36/198) had a new-onset NAFLD. Remission of NAFLD occurred among 38.10% (n = 45/118) of those with an NAFLD diagnosis at baseline. At baseline, subjects with high meat consumption had a worse metabolic profile, including higher serum glucose levels and homeostasis model assessment for insulin resistance (HOMA-IR).
There was no significant association between meat consumption of any type and NAFLD. However, high consumption of red and/or processed meat was associated with a new onset/persistence (OR = 3.07, 95% CI 1.31-7.21, p = 0.010) or incidence of NAFLD with elevated ALT (OR = 3.75, 95% CI 1.21-11.62, p = 0.022), adjusting for the following potential confounders and mediators: baseline age (years), gender, BMI (Kg/m2), energy (Kcal), protein (% total Kcal), and cholesterol intake (mg/day). High processed meat consumption was associated with new onset/persistence of NAFLD with elevated ALT (OR = 2.52, 95% CI 1.14-5.59, p = 0.023). Likewise, unprocessed red meat consumption was positively associated with new onset/persistence of NAFLD with elevated ALT (OR = 2.28, 95% CI 1.04-4.99, p = 0.039).
In a univariate analysis, subjects with high total meat or red and/or processed meat consumption at both the baseline and follow-up evaluations had the highest prevalence of NAFLD compared to those with low meat consumption at one or both evaluations, with a modest dose-response trend across categories (p for trend = 0.002 for total meat, and 0.013 for red and/or processed meat). A similar trend was also shown in a multivariable analysis adjusting for all potential confounders and mediators. Consistently high total meat consumption was associated with 2.55-fold (95% CI 1.27-5.12, p = 0.009) greater odds for new onset/persistence of NAFLD compared to consistently low meat consumption.
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A sensitivity analysis found similar associations in a subsample of 101 subjects undergoing liver US at both time points. In a multivariable model, high baseline consumption of total meat and of the different types of meat was associated with new onset/persistence of NAFLD (OR = 4.82, 95% CI 1.48-15.73, p = 0.009; OR = 4.51, 1.44-14.11, p = 0.010; OR = 3.15, 1.09-9.10, p = 0.035; OR = 3.99, 1.31-12.22, p = 0.015 for total, red and/or processed, processed, and unprocessed red meat consumption, respectively). As for changes in meat consumption, an increase of 10% (vs. no change or decrease) in total meat (OR = 3.05, 95% CI 1.09-8.49, p = 0.033), red and/or processed meat (OR = 3.23, 1.11-9.42, p = 0.032), or unprocessed red meat (OR = 5.41, 1.74-16.78, p = 0.003) was associated with new onset/persistence of NAFLD, along with lower odds of NAFLD remission (OR = 0.09, 95% CI 0.01-0.58, p = 0.003; OR = 0.21, 0.05-0.93, p = 0.039; OR = 0.11, 0.02-0.58, p = 0.009, for total meat, red and/or processed meat, and unprocessed meat, respectively).
In a univariate analysis, the prevalence of presumed significant fibrosis at the follow-up evaluation was the highest among those with consistently high red and/or processed meat consumption, but it was not statistically significant. However, in a multivariable analysis, consistently high red and/or processed meat consumption was associated with 4.77-fold (95% CI 1.36-16.69, p = 0.014) greater odds for significant fibrosis compared to consistently low consumption.
Stress and Lifestyle Factors
Diet is only one facet of cardiometabolic risk. Research also highlights how chronic stress can adversely affect cardiovascular disease (CVD) outcomes. A cross-sectional study of 145 middle-aged women found higher hair cortisol and cortisone correlated with increased waist circumference, blood pressure, and higher SCORE2 risk index for CVD. While carnivore dieters may experience initial weight loss or glucose control, psychological stress from stringent dietary restrictions or social isolation may further complicate a patient’s cardiometabolic profile over time. Addressing these stressors, alongside dietary modifications, is crucial in primary care management.
Proceed with Caution: A Call for Vigilance in Primary Care
Primary care providers are often the first to encounter patients exploring restrictive eating patterns, including the carnivore diet. Given the potential for significant rises in LDL cholesterol levels, micronutrient deficiencies, and other metabolic complications, general practitioners should remain vigilant. Before recommending or endorsing any diet, it is prudent to obtain thorough lipid panels (ideally including LDL particle number or apoB) when extreme hyperlipidaemia is apparent. It is also essential to screen for micronutrient insufficiencies, particularly because eliminating fruits, vegetables, and whole grains can deprive patients of important vitamins and fibre. Evaluating liver function through AST and ALT tests-and calculating FIB-4 if there are signs of metabolic syndrome-helps detect subclinical fatty liver disease before it progresses. Where persistently high LDL cholesterol is observed, consider imaging studies such as carotid ultrasound or coronary artery calcium scoring to assess for early signs of atherosclerosis.
Lifestyle and psychological support can be invaluable, especially if restrictive eating patterns trigger stress or social isolation. Finally, ensure shared decision-making by highlighting the limited long-term safety data on the carnivore diet and presenting evidence-based alternatives-such as a Mediterranean or moderate low-carbohydrate approach-to protect patients’ cardiovascular and metabolic health.
Referring patients to a registered dietitian can be a key step in guiding them through any significant dietary change, including highly restrictive patterns such as the carnivore diet. Dietitians are trained to assess individual nutritional needs, identify potential micronutrient imbalances, and tailor eating plans to address specific health goals and medical conditions. By incorporating a dietitian into the care team, primary care providers can ensure that patients receive ongoing support, education, and practical strategies for meal planning, recipe modification, and balanced supplementation if necessary. This collaborative approach helps patients remain well-informed about the risks and benefits of their chosen eating pattern and reduces the likelihood of unintended health consequences.
Although a carnivore diet may lead to short-term weight loss or improved glycaemic parameters in some individuals, the mounting evidence of potentially severe hyperlipidaemia, early atherosclerosis, and dietary nutrient gaps should raise red flags. For GPs, maintaining a high index of suspicion and carefully monitoring cholesterol, liver function, and overall cardiometabolic status is critical.
Alternative Dietary Approaches
While the carnivore diet focuses on animal products, other dietary patterns have demonstrated benefits for liver health. The Mediterranean diet, rich in fruits, vegetables, whole grains, and healthy fats, is often recommended for patients with NAFLD. It emphasizes eating fruits, veggies, whole grains, beans, nuts, legumes, olive oil, and flavorful herbs and spices; fish and seafood at least a couple of times a week; and poultry, eggs, cheese and yogurt in moderation, while saving sweets and red meat for special occasions. In addition to being good for people with non-alcoholic fatty liver disease, the Mediterranean diet has been associated with a decreased risk of heart disease, and it's also been shown to reduce blood pressure and bad LDL cholesterol. And it can be in line with the American Diabetes Association's nutrition guidance.
The Importance of Individualized Nutrition
A key role the dietitian plays is individualizing the nutrition plan for each patient. Adapting to a Mediterranean diet is hard for patients because we are surrounded by convenience foods and junk on a daily basis. This diet is focused. It is important for patients to be able to sit down and learn about the benefits of the recommended diet and ask questions.