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The carnivore diet

Why we do not recommend the carnivore diet

Dr Shireen Kassam, Founder and Director of Plant-Based Health Professionals UK

The carnivore diet, which consists exclusively of animal-based foods, has gained popularity in recent years. While some proponents claim it offers numerous health benefits, many of these claims lack scientific backing. Here are ten key reasons why we do not recommend the carnivore diet.

  1. Lack of fibre is detrimental to health

The carnivore diet eliminates all plant-based foods, meaning it provides zero fibre. Fibre is essential for gut microbiome diversity, supporting beneficial bacteria and reducing the risk of digestive disorders such as constipation, diverticulitis, and colorectal cancer. In addition, the consumption of fibre is associated with a reduction in risk of a number of common chronic conditions including type 2 diabetes, heart disease, stroke and dementia.1,2

  1. Increased risk of heart disease

A diet high in animal foods results in an increased intake of saturated fat and dietary cholesterol. This in turn leads to an increased risk of atherosclerotic cardiovascular diseases such as coronary artery disease (heart disease) and stroke, through the elevation of cholesterol levels in the body, specifically apolipoprotein B containing molecules such as LDL-cholesterol.3–5

  1. Deficiency of essential nutrients

Excluding plant foods leads to deficiencies in key micronutrients, including but not limited to6,7:

  • Vitamin C – important for immune function
  • Magnesium – essential for muscle and nerve function
  • Folate – critical for DNA synthesis, red blood cell production and preventing neural tube defects
  • Potassium – vital for blood pressure regulation, nerve signalling, and muscle contractions
  • Phytonutrients and antioxidants – reduce inflammation and cellular stress and protect against chronic diseases
  1. Increased cancer risk from processed and red meats

The World Health Organization (WHO) classifies processed meats as a Group 1 carcinogen and red meat as a Group 2A probable carcinogen due to the association with higher rates of colorectal cancer. Several factors may contribute to this risk. Carcinogenic compounds such as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) form when meat is cooked at high temperatures. Processed meats also expose consumers to nitrites and nitrates, while red meat increases haem iron intake, which may promote cancer development.8

  1. No evidence it is superior for weight loss

Proponents claim the carnivore diet is ideal for weight loss, but any diet that leads to a caloric deficit will result in weight loss.9 Studies suggest very low carbohydrate, high-protein diets help with satiety, but long-term sustainability and adherence is difficult, and weight loss is usually not maintained. Weight loss with very low carbohydrate or ketogenic diets are often associated with loss of muscle mass and there are concerns about elevations in LDL-cholesterol levels.10

  1. Increased risk of insulin resistance and type 2 diabetes

Although some individuals claim a carnivore diet improves insulin sensitivity, studies show that excessive red and processed meat consumption is associated with a higher risk of type 2 diabetes (11). The absence of fibre, increased intake of saturated fat and haem iron all contribute to insulin resistance, which may also worsen conditions such as PCOS. In fact, diets with low or no meat consumption are consistently associated with a lower risk of type 2 diabetes.12,13

  1. Lack of scientific studies supporting long-term safety

There are no long-term studies proving the safety or benefits of the carnivore diet. Most evidence comes from short-term anecdotes or small, uncontrolled studies.14 In contrast, decades of research support plant-rich diets like the Mediterranean and DASH diets as well as exclusively plant-based diets for long-term health.15,16

  1. Can lead to mental health issues

The gut and brain are closely connected, and the lack of prebiotic fibre from plant foods can negatively impact mental health. Studies suggest low-fibre, high-fat diets may increase inflammation and contribute to anxiety and depression, in part due to adverse impacts on the gut microbiome.17

  1. Not evolutionarily consistent

Despite claims that humans evolved to eat a meat-only diet, anthropological evidence suggests early humans were omnivores, consuming a diverse diet of meat, plants, nuts, and seeds.18,19 Many of the longest-living populations today (e.g., in the Blue Zones) follow plant-rich diets rather than carnivorous ones.20

  1. Terrible for environmental health

Animal agriculture is a key driver of greenhouse gas emissions, creating more than half of all emissions from the farming sector.21 Not only that, animal agriculture is the leading cause of land use change and biodiversity loss while also contributing significantly to air, land and water pollution, antibiotic resistant infections and the generation of new infectious threat.22–25 It is clear from an enormous amount of scientific data that to meet our nature and climate targets we have to move away from farming animals towards a plant-based food system.26 A fully plant-based diet has only a quarter of the impact on the environment than a typical omnivorous diet, and so any shift we can make towards eating more plants will be better for the planet.

Final Verdict:

The carnivore diet is nutritionally unbalanced, unsustainable, and potentially harmful in the long run. While short-term benefits may come from eliminating processed foods, there are far healthier ways to achieve health goals without sacrificing essential nutrients.

References

  1. Veronese N, Solmi M, Caruso MG, Giannelli G, Osella AR, Evangelou E, et al. Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses. Am J Clin Nutr [Internet]. 2018 Mar;107(3):436–44. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0002916522028131
  2. McKeown NM, George C Fahey J, Slavin J, Kamp J-W van der. Fibre intake for optimal health: how can healthcare professionals support people to reach dietary recommendations? BMJ [Internet]. 2022 Jul 20;378:e054370. Available from: http://www.bmj.com/content/378/bmj-2020-054370.abstract
  3. Sacks FM, Lichtenstein AH, Wu JHY, Appel LJ, Creager MA, Kris-Etherton PM, et al. Dietary fats and cardiovascular disease: A presidential advisory from the American Heart Association. Circulation. 2017.
  4. Nguyen XT, Li Y, Nyaeme MS, Panigrahy N, Houghton S, Ivey KL, et al. Dietary Cholesterol and Myocardial Infarction in the Million Veteran Program. J Am Heart Assoc [Internet]. 2025 Feb 18;14(4):e036819. Available from: https://doi.org/10.1161/JAHA.124.036819
  5. Marmagkiolis K, Caballero J, Iliescu C. Yellowish Nodules on a Man Consuming a Carnivore Diet. JAMA Cardiol [Internet]. 2025 Mar 1;10(3):297. Available from: https://doi.org/10.1001/jamacardio.2024.5209
  6. O’Hearn A. Can a carnivore diet provide all essential nutrients? Curr Opin Endocrinol Diabetes Obes [Internet]. 2020 Oct;27(5):312–6. Available from: https://journals.lww.com/co-endocrinology/fulltext/2020/10000/can_a_carnivore_diet_provide_all_essential.11.aspx
  7. Neufingerl N, Eilander A. Nutrient Intake and Status in Adults Consuming Plant-Based Diets Compared to Meat-Eaters: A Systematic Review. Vol. 14, Nutrients. 2022.
  8. Bouvard V, Loomis D, Guyton KZ, Grosse Y, Ghissassi F El, Benbrahim-Tallaa L, et al. Carcinogenicity of consumption of red and processed meat. Lancet Oncol [Internet]. 2015 Dec;16(16):1599–600. Available from: https://linkinghub.elsevier.com/retrieve/pii/S1470204515004441
  9. Gardner CD, Trepanowski JF, Del Gobbo LC, Hauser ME, Rigdon J, Ioannidis JPA, et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion. JAMA [Internet]. 2018 Feb 20;319(7):667. Available from: http://jama.jamanetwork.com/article.aspx?doi=10.1001/jama.2018.0245
  10. Patikorn C, Saidoung P, Pham T, Phisalprapa P, Lee YY, Varady KA, et al. Effects of ketogenic diet on health outcomes: an umbrella review of meta-analyses of randomized clinical trials. BMC Med [Internet]. 2023 May 25;21(1):196. Available from: https://doi.org/10.1186/s12916-023-02874-y
  11. Li C, Bishop TRP, Imamura F, Sharp SJ, Pearce M, Brage S, et al. Meat consumption and incident type 2 diabetes: an individual-participant federated meta-analysis of 1·97 million adults with 100 000 incident cases from 31 cohorts in 20 countries. Lancet Diabetes Endocrinol [Internet]. 2024 Sep 1;12(9):619–30. Available from: https://doi.org/10.1016/S2213-8587(24)00179-7
  12. Thompson AS, Candussi CJ, Tresserra-Rimbau A, Jennings A, Bondonno NP, Hill C, et al. A healthful plant-based diet is associated with lower type 2 diabetes risk via improved metabolic state and organ function: A prospective cohort study. Diabetes Metab [Internet]. 2024;50(1):101499. Available from: https://www.sciencedirect.com/science/article/pii/S1262363623000812
  13. Tonstad S, Stewart K, Oda K, Batech M, Herring RP, Fraser GE. Vegetarian diets and incidence of diabetes in the Adventist Health Study-2. Nutr Metab Cardiovasc Dis [Internet]. 2013 Apr;23(4):292–9. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0939475311001700
  14. Lennerz BS, Mey JT, Henn OH, Ludwig DS. Behavioral Characteristics and Self-Reported Health Status among 2029 Adults Consuming a “Carnivore Diet.” Curr Dev Nutr [Internet]. 2021 Dec 1;5(12):nzab133. Available from: https://doi.org/10.1093/cdn/nzab133
  15. Shan Z, Wang F, Li Y, Baden MY, Bhupathiraju SN, Wang DD, et al. Healthy Eating Patterns and Risk of Total and Cause-Specific Mortality. JAMA Intern Med [Internet]. 2023 Feb 1;183(2):142. Available from: https://doi.org/10.1001/jamainternmed.2022.6117
  16. Raj S, Guest NS, Landry MJ, Mangels AR, Pawlak R, Rozga M. Vegetarian Dietary Patterns for Adults: A Position of the Academy of Nutrition and Dietetics. J Acad Nutr Diet [Internet]. 2025 Feb 24; Available from: https://doi.org/10.1016/j.jand.2025.02.002
  17. Marx W, Manger SH, Blencowe M, Murray G, Ho FY-Y, Lawn S, et al. Clinical guidelines for the use of lifestyle-based mental health care in major depressive disorder: World Federation of Societies for Biological Psychiatry (WFSBP) and Australasian Society of Lifestyle Medicine (ASLM) taskforce. World J Biol Psychiatry [Internet]. 2023 May 28;24(5):333–86. Available from: https://doi.org/10.1080/15622975.2022.2112074
  18. Lüdecke T, Leichliter JN, Stratford D, Sigman DM, Vonhof H, Haug GH, et al. Australopithecus at Sterkfontein did not consume substantial mammalian meat. Science (80- ) [Internet]. 2025 Jan 17;387(6731):309–14. Available from: https://doi.org/10.1126/science.adq7315
  19. Moubtahij Z, McCormack J, Bourgon N, Trost M, Sinet-Mathiot V, Fuller BT, et al. Isotopic evidence of high reliance on plant food among Later Stone Age hunter-gatherers at Taforalt, Morocco. Nat Ecol Evol [Internet]. 2024 Apr 29;8(5):1035–45. Available from: https://doi.org/10.1038/s41559-024-02382-z
  20. Buettner D, Skemp S. Blue Zones: Lessons From the World’s Longest Lived. American Journal of Lifestyle Medicine. 2016.
  21. Crippa M, Solazzo E, Guizzardi D, Monforti-Ferrario F, Tubiello FN, Leip A. Food systems are responsible for a third of global anthropogenic GHG emissions. Nat Food [Internet]. 2021 Mar 8;2(3):198–209. Available from: https://www.nature.com/articles/s43016-021-00225-9
  22. Poore J, Nemecek T. Reducing food’s environmental impacts through producers and consumers. Science (80- ) [Internet]. 2018 Jun;360(6392):987–92. Available from: https://www.science.org/doi/10.1126/science.aaq0216
  23. Benton T, Bieg C, Harwatt H, Pudassaini R, Wellesley L. Food system impacts on biodiversity loss Three levers for food. Energy, Environment and Resources Programme. 2021.
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