The Dangers of The Carnivore Diet

Introduction

In recent years, the carnivore diet has gained significant popularity among those seeking weight loss and improved health outcomes. This highly restrictive eating pattern advocates consuming only animal products—primarily meat, with some allowances for eggs and certain dairy products—while eliminating all plant-based foods. Proponents of the diet claim numerous benefits, from weight loss and reduced inflammation to improved mental clarity and resolution of autoimmune conditions. However, behind these appealing promises lies a concerning reality: the carnivore diet may pose serious risks to long-term health.

The carnivore diet, sometimes called the “zero carb” diet, represents perhaps the most extreme version of low-carbohydrate eating plans. Unlike more moderate approaches that reduce carbohydrate intake while maintaining some plant foods, the carnivore diet eliminates entire food groups that have long been considered essential components of a balanced diet. This radical departure from conventional nutritional wisdom has raised significant concerns among healthcare professionals, dietitians, and medical researchers.

As Dr. Howard E. LeWine, Chief Medical Editor at Harvard Health Publishing, notes, the carnivore diet is essentially an extreme version of the ketogenic diet, forcing the body into a state of ketosis where it burns fat for energy instead of carbohydrates. While this metabolic state can indeed lead to rapid weight loss in the short term, the long-term consequences of maintaining such a restrictive eating pattern may outweigh any temporary benefits.

This article examines the potential dangers associated with the carnivore diet, exploring the scientific evidence behind concerns related to cardiovascular health, nutritional deficiencies, digestive issues, kidney function, cancer risk, and more. By understanding these risks, individuals can make more informed decisions about their dietary choices and avoid potentially harmful nutritional extremes.

Understanding the Carnivore Diet

The carnivore diet represents one of the most restrictive eating patterns to gain mainstream attention in recent years. At its core, this diet permits only foods derived from animal sources while eliminating all plant-based foods entirely. Adherents consume primarily meat—beef, pork, poultry, and fish—along with eggs and limited dairy products, particularly those low in lactose such as butter, hard cheeses, and heavy cream. Water and black coffee are typically the only beverages allowed, though some followers permit small amounts of tea as well.

What makes this diet particularly extreme is not just what it includes, but what it excludes. The carnivore diet eliminates all fruits, vegetables, grains, legumes, nuts, seeds, and plant oils. This means no fiber-rich foods, no plant-based vitamins and minerals, and virtually no carbohydrates. As Lisa Marsh, a registered dietitian at Baylor Scott & White Signature Medicine, explains, “A carnivore diet is the most ketogenic diet because it allows for almost no carbs, whereas other keto diets reduce carbohydrate intake to less than 50 grams per day.”

The modern popularity of the carnivore diet stems largely from controversial evolutionary theories suggesting that ancestral human populations subsisted primarily on meat and fish. Proponents argue that the shift to agricultural diets high in carbohydrates is responsible for many modern chronic health conditions. They claim the carnivore diet can reduce inflammation, improve mental health, stabilize blood sugar levels, and even address autoimmune conditions. However, as multiple medical experts have noted, there is little reliable scientific research to support these claims.

In comparison to other restrictive diets, the carnivore approach is even more limiting than the ketogenic diet, which still permits low-carbohydrate vegetables, some berries, and a wider variety of dairy products. While both diets aim to induce ketosis—a metabolic state where the body burns fat for energy instead of carbohydrates—the carnivore diet takes this principle to an extreme by eliminating virtually all sources of carbohydrates and many essential nutrients found only in plant foods.

The diet’s rigid structure makes it particularly challenging to follow long-term, a point emphasized by Shannon Haynes, a registered dietitian at Backus Hospital: “It’s true that this diet can show results – initially. But in the long term, it’s a very challenging diet to follow. It also comes with a host of other health risks.” This sustainability concern, combined with the numerous health risks discussed in subsequent sections, raises serious questions about the carnivore diet’s viability as a long-term eating pattern.

Cardiovascular Health Concerns

Perhaps the most significant health risk associated with the carnivore diet relates to cardiovascular health. By design, this diet is exceptionally high in saturated fat and cholesterol—nutrients that have been consistently linked to increased risk of heart disease when consumed in excess. The American Heart Association and numerous other health organizations have long recommended limiting saturated fat intake due to its well-established connection to elevated LDL (low-density lipoprotein) cholesterol levels, often referred to as “bad” cholesterol.

Dr. Howard E. LeWine of Harvard Health Publishing specifically warns about this danger: “While some keto diets can emphasize the intake of healthier mono- and polyunsaturated fats, that’s not the case with carnivore diets. Animal fat is mostly saturated fat, which is the unhealthiest type of fat because it raises levels of LDL (bad) cholesterol.” This elevation in LDL cholesterol is a primary risk factor for atherosclerosis—the buildup of fatty deposits in arterial walls that can lead to heart attacks and strokes.

The carnivore diet’s emphasis on red meat, particularly in processed forms, compounds these cardiovascular concerns. A 2020 meta-analysis published in JAMA Internal Medicine found that higher intake of red meat, especially processed red meat, was associated with higher risk of cardiovascular disease. The researchers concluded that replacing red meat with healthier protein sources was associated with lower risk of heart disease.

Additionally, the high sodium content often associated with the carnivore diet—particularly when processed meats are consumed regularly—can contribute to hypertension (high blood pressure), another significant risk factor for heart disease. As Lisa Marsh from Baylor Scott & White Health notes, “The carnivore diet recommends adding salt to the diet to enhance the flavor of meat,” which may further exacerbate cardiovascular risks.

The absence of heart-protective foods in the carnivore diet is equally concerning. Fruits, vegetables, whole grains, and legumes—all prohibited on the carnivore diet—contain fiber, antioxidants, and other compounds that have been shown to reduce inflammation and improve heart health markers. By eliminating these foods entirely, carnivore diet adherents miss out on these protective effects, potentially increasing their cardiovascular risk over time.

Cardiologists and nutrition experts generally agree that diets high in saturated fat and animal products, while low in fiber and plant nutrients, create an unfavorable profile for long-term heart health. The temporary weight loss that may occur on the carnivore diet should be weighed against these significant cardiovascular concerns when considering its overall impact on health.

Nutritional Deficiencies

One of the most significant concerns with the carnivore diet is the risk of developing serious nutritional deficiencies. By eliminating all plant foods, followers of this diet miss out on numerous essential vitamins, minerals, and other nutrients that are primarily or exclusively found in fruits, vegetables, whole grains, and legumes.

Vitamin C deficiency represents perhaps the most immediate nutritional concern. This essential vitamin, crucial for immune function, collagen synthesis, and wound healing, is found predominantly in fruits and vegetables—foods entirely excluded from the carnivore diet. While small amounts of vitamin C exist in fresh meat, particularly organ meats like liver, the cooking process destroys much of this heat-sensitive nutrient. Shannon Haynes, RD, from Backus Hospital, specifically highlights vitamin C as one of the critical nutrients missing from the carnivore diet. Historically, severe vitamin C deficiency led to scurvy among sailors and others without access to fresh produce, causing symptoms like bleeding gums, poor wound healing, and eventually death if left untreated.

Beyond vitamin C, the carnivore diet creates significant risks for deficiencies in other micronutrients. Potassium and magnesium—minerals essential for proper muscle function, nerve transmission, and heart rhythm regulation—are found abundantly in plant foods but are limited in animal products. As noted by nutrition experts at St. Vincent’s Medical Center, these deficiencies can have serious health implications over time.

The complete absence of dietary fiber represents another profound nutritional gap in the carnivore diet. While not technically a nutrient, fiber plays crucial roles in human health, including maintaining digestive regularity, feeding beneficial gut bacteria, helping control blood sugar levels, and reducing cholesterol. Lisa Marsh, MS, RD, LD, explains that “fiber provides numerous benefits to overall health, including lowering cholesterol, stabilizing blood sugar and promoting weight loss.” The current recommended daily intake of fiber is at least 25 grams for women and at least 38 grams for men—amounts impossible to achieve on a diet devoid of plant foods.

Additionally, the carnivore diet lacks phytonutrients and antioxidants found exclusively in plant foods. These compounds help combat oxidative stress and inflammation in the body and have been associated with reduced risk of various chronic diseases. Research has consistently shown that diets rich in plant-based foods are associated with lower risk of conditions such as Alzheimer’s disease, heart disease, and Type 2 diabetes—protective effects that carnivore diet adherents forfeit.

While proponents argue that certain animal products like organ meats can provide some of these missing nutrients, the reality is that few modern carnivore diet followers regularly consume these foods in sufficient quantities. Even with strategic organ meat consumption, the diet still creates significant nutritional gaps that may lead to both short-term symptoms and long-term health consequences.

Digestive Health Issues

The carnivore diet’s complete elimination of dietary fiber creates significant concerns for digestive health. Fiber, found exclusively in plant foods, plays a crucial role in maintaining proper digestive function and overall gut health. Without it, carnivore diet followers often experience substantial changes in their digestive processes, many of which can be detrimental to long-term health.

Constipation is perhaps the most immediate and common digestive issue reported by those following the carnivore diet. As Lisa Marsh, MS, RD, LD, from Baylor Scott & White Health explains, “The absence of fiber in your diet might initially reduce gas and bloating, however, over time, it can cause constipation and other digestive issues.” Dietary fiber adds bulk to stool and helps maintain regular bowel movements. Without this crucial component, many people experience uncomfortable and potentially harmful changes in their elimination patterns.

Beyond constipation, the carnivore diet significantly alters the gut microbiome—the complex ecosystem of bacteria that inhabits the digestive tract. A healthy gut microbiome depends on dietary fiber as its primary food source. These beneficial bacteria ferment fiber into short-chain fatty acids that nourish the cells lining the colon and regulate various aspects of digestive and immune function. Shannon Haynes, RD, notes that the carnivore diet “can affect your gut microbiome, which is important for digestion and immunity.” Research increasingly links disruptions in the gut microbiome to various health problems, including inflammatory bowel disease, metabolic disorders, and even mental health conditions.

The lack of fiber in the carnivore diet also raises serious concerns about colon health. Fiber plays a protective role against colorectal cancer, one of the most common and deadly forms of cancer worldwide. According to Lisa Marsh, “The higher the consumption of fiber, the lower the risk of colon cancer.” This protective effect occurs through multiple mechanisms, including reducing transit time of potential carcinogens through the digestive tract, diluting harmful substances, and promoting beneficial bacterial activity that may inhibit cancer development.

Additionally, the high protein content of the carnivore diet can lead to digestive discomfort for many individuals. When protein is consumed in excessive amounts without adequate fiber, it can lead to increased production of potentially harmful metabolic byproducts that must be processed by the liver and kidneys. This can result in digestive symptoms like bloating, gas, and discomfort, particularly during the initial adaptation period.

While some carnivore diet proponents claim digestive improvements, particularly those transitioning from diets high in processed foods, nutrition experts caution that these short-term changes may come at the expense of long-term digestive health. The temporary reduction in certain digestive symptoms must be weighed against the substantial evidence supporting fiber’s essential role in maintaining digestive wellness and preventing serious conditions like colorectal cancer.

Kidney and Bone Health

The carnivore diet’s extremely high protein content poses significant concerns for kidney and bone health over time. While protein is an essential macronutrient, consuming it in excessive amounts—as typically occurs on the carnivore diet—can place substantial stress on the kidneys and potentially affect bone mineral density.

Dr. Howard E. LeWine of Harvard Health Publishing specifically warns that “the very high protein intake associated with the carnivore diet can lead to impaired kidney function.” The kidneys play a crucial role in filtering waste products from protein metabolism, particularly nitrogen-containing compounds like urea. When protein is consumed in excessive amounts, the kidneys must work harder to eliminate these waste products, potentially leading to increased stress on these vital organs over time.

This concern is particularly relevant for individuals with pre-existing kidney conditions or risk factors for kidney disease. As Lisa Marsh from Baylor Scott & White Health notes, “Consuming a large amount of animal protein can lead to unwanted stress on the kidneys, especially if you already experience kidney issues.” For these individuals, the extreme protein load of the carnivore diet could accelerate kidney function decline or exacerbate existing problems.

Beyond general kidney stress, the carnivore diet significantly increases the risk of kidney stones. Dr. LeWine specifically identifies kidney stones as one of the “longer-term concerns about keto diets, especially the carnivore diet.” This increased risk stems from several factors: the high animal protein intake increases urinary calcium excretion and uric acid levels, while the absence of plant foods reduces urinary citrate—a compound that normally helps prevent stone formation. The combination of these factors creates an environment highly conducive to kidney stone development.

The carnivore diet also raises concerns about gout, a painful form of inflammatory arthritis caused by elevated uric acid levels in the bloodstream. Animal products, particularly red meat and organ meats heavily emphasized in the carnivore diet, are rich in purines—compounds that break down into uric acid during digestion. Shannon Haynes, RD, notes that “ketosis puts stress on your whole body” and specifically mentions gout as a potential consequence. For individuals with a genetic predisposition to gout or a history of the condition, the carnivore diet represents a particularly high-risk eating pattern.

Perhaps most concerning for long-term health is the potential impact on bone density. Dr. LeWine identifies osteoporosis as another significant risk associated with the carnivore diet. High-protein diets, particularly those rich in animal protein, can increase calcium excretion through the urine. Without adequate calcium intake and the bone-protective compounds found in many plant foods, this could potentially accelerate bone mineral loss over time. Additionally, the metabolic acidosis that can result from extremely low-carbohydrate diets may further contribute to bone demineralization as the body releases calcium from bones to buffer blood acidity.

While proponents of the carnivore diet often dismiss these concerns as theoretical or applicable only to those with pre-existing conditions, the medical consensus remains clear: extremely high protein intake combined with the absence of plant-derived nutrients creates legitimate concerns for kidney function and bone health that should not be overlooked when evaluating this diet’s safety profile.

Cancer Risk Factors

The carnivore diet’s heavy emphasis on animal products, particularly red and processed meats, raises significant concerns regarding cancer risk. Multiple large-scale epidemiological studies and meta-analyses have established links between high consumption of these foods and increased risk of certain cancers, most notably colorectal cancer.

The World Health Organization’s International Agency for Research on Cancer (IARC) classified processed meats as Group 1 carcinogens—substances definitively linked to cancer—and red meat as Group 2A, probably carcinogenic to humans. This classification came after reviewing hundreds of studies examining the relationship between meat consumption and cancer risk. The evidence was particularly strong for colorectal cancer, with the IARC concluding that each 50-gram portion of processed meat eaten daily increases the risk of colorectal cancer by about 18%.

Lisa Marsh from Baylor Scott & White Health specifically highlights this concern, noting that “a diet high in red and processed meats has been linked to an increased risk of cancer, including colon and rectal cancer.” The mechanisms behind this increased risk are multifaceted. When meat is cooked at high temperatures, it can form heterocyclic amines and polycyclic aromatic hydrocarbons—compounds that have been shown to cause cancer in animal studies. Additionally, heme iron found in red meat can damage the cells lining the colon and promote the formation of N-nitroso compounds, which are also carcinogenic.

The cancer risk associated with the carnivore diet is compounded by the complete absence of protective plant compounds. Fruits, vegetables, whole grains, and legumes—all excluded on the carnivore diet—contain thousands of phytochemicals with anti-cancer properties. These compounds work through various mechanisms, including reducing inflammation, neutralizing free radicals, inhibiting cancer cell growth, and supporting the immune system’s ability to identify and eliminate abnormal cells.

Fiber, exclusively found in plant foods, plays a particularly important protective role against colorectal cancer. As Lisa Marsh emphasizes, “The higher the consumption of fiber, the lower the risk of colon cancer.” Fiber helps move potential carcinogens through the digestive tract more quickly, reducing their contact time with the intestinal lining. It also feeds beneficial gut bacteria that produce short-chain fatty acids like butyrate, which have been shown to inhibit colon cancer development.

The carnivore diet creates a concerning scenario where known cancer-promoting foods are consumed in large quantities while cancer-protective foods are completely eliminated. This combination potentially creates an environment highly conducive to cancer development, particularly in the digestive tract. While individual cancer risk depends on multiple factors, including genetics and lifestyle, the scientific consensus strongly suggests that diets high in red and processed meats while low in plant foods increase cancer risk over time.

Proponents of the carnivore diet often point to the absence of refined carbohydrates and processed foods as a cancer-protective aspect of their eating pattern. While limiting these foods may indeed offer some benefits, this potential advantage is likely overshadowed by the substantial evidence linking high meat consumption to increased cancer risk and the protective effects of the plant foods excluded from this diet.

Sustainability Concerns

Beyond the immediate health risks, the carnivore diet raises significant concerns regarding long-term sustainability—both in terms of personal adherence and broader environmental impact. These factors, while sometimes overlooked in discussions of diet efficacy, play crucial roles in determining whether an eating pattern is truly viable and responsible.

From a personal sustainability perspective, the extreme restrictiveness of the carnivore diet makes it exceptionally difficult to maintain over time. Shannon Haynes, RD, specifically notes that “it’s a very challenging diet to follow” long-term. This difficulty stems from several factors, including the complete elimination of many commonly enjoyed foods, potential social isolation during meals, and the monotony that can develop when diet choices are severely limited. While short-term adherence may be possible through motivation and novelty, maintaining such a restrictive eating pattern indefinitely proves challenging for most individuals.

The social aspects of following the carnivore diet can be particularly problematic. Shared meals are fundamental to human social connection across cultures, and severely restricting food choices can lead to isolation or difficulty participating in social gatherings. Family dinners, workplace lunches, holiday celebrations, and dining out all become significantly more complicated when adhering to such a restrictive eating pattern. This social strain can impact quality of life and potentially lead to reduced dietary adherence over time.

From an environmental perspective, the carnivore diet’s heavy reliance on animal products raises substantial concerns about ecological sustainability. Animal agriculture, particularly beef production, is associated with higher greenhouse gas emissions, greater land use requirements, and increased water consumption compared to plant food production. A 2018 study published in Science found that meat and dairy provide just 18% of calories and 37% of protein globally, but use 83% of farmland and produce 60% of agriculture’s greenhouse gas emissions. If adopted widely, diets centered exclusively on animal products would likely exacerbate these environmental challenges.

The ethical considerations surrounding intensive animal agriculture also present concerns for some individuals considering the carnivore diet. The welfare conditions of animals in industrial farming operations have faced increasing scrutiny, raising questions about the ethical implications of diets that rely exclusively on animal products, particularly when consumed in the quantities required by the carnivore approach.

Lisa Marsh from Baylor Scott & White Health emphasizes a crucial point about dietary sustainability: “The best diet is the one you can sustain the longest. Work on making small improvements to your diet, which over time can really add up.” This perspective highlights the importance of finding eating patterns that are not only nutritionally sound but also personally sustainable and enjoyable over the long term.

The combination of these factors—personal adherence challenges, social complications, environmental concerns, and ethical considerations—creates significant questions about the carnivore diet’s viability as a long-term eating pattern for most individuals. While short-term adherence may yield certain results, the multiple sustainability barriers suggest that for many people, this approach may represent an unsustainable dietary extreme rather than a realistic long-term solution.

Healthier Alternatives

Given the numerous health concerns associated with the carnivore diet, many nutrition experts recommend more balanced and sustainable approaches to achieving similar health goals. These alternatives can provide many of the benefits sought by carnivore diet adherents while avoiding the most serious risks.

For individuals primarily seeking weight loss, several evidence-based dietary approaches offer more balanced alternatives. The Mediterranean diet, consistently ranked among the healthiest eating patterns by nutrition experts, emphasizes olive oil, fish, nuts, legumes, fruits, vegetables, and whole grains while limiting red meat and processed foods. This eating pattern has been extensively studied and associated with reduced risk of heart disease, certain cancers, and overall mortality. Unlike the carnivore diet, it provides ample fiber, phytonutrients, and a balanced nutrient profile while still allowing for moderate protein intake and satisfying meals.

Shannon Haynes, RD, specifically recommends a more balanced approach: “Instead of cutting out a food group, try focusing on balance.” She suggests using the MyPlate approach, “filling a quarter of your plate with protein, a quarter with carbs, and half with vegetables. This can help you create a balanced, satisfying plate, without cutting out your favorite foods.” This moderate approach acknowledges the importance of protein while ensuring adequate intake of other essential nutrients.

For those attracted to the carnivore diet’s low-carbohydrate aspect, a more moderate ketogenic or low-carb approach that includes non-starchy vegetables can provide metabolic benefits while maintaining some fiber and micronutrient intake. This modified approach allows for the inclusion of leafy greens, cruciferous vegetables, and other low-carbohydrate plant foods that provide essential nutrients missing from the strict carnivore diet.

Lisa Marsh from Baylor Scott & White Health emphasizes the value of gradual, sustainable changes: “A gradual lifestyle change approach is more manageable than tackling a trendy diet that is drastically different than your usual diet. Eating a balanced diet with a variety of healthy foods is more sustainable and is likely to be more beneficial to your health in the long run.” This perspective acknowledges that extreme dietary changes are often difficult to maintain and may not provide lasting benefits.

For individuals with specific health concerns that led them to consider the carnivore diet, working with healthcare professionals to develop personalized nutrition plans represents a safer approach. Registered dietitians can help identify food sensitivities, address specific nutritional needs, and develop eating patterns that support individual health goals without eliminating entire food groups. This personalized approach recognizes that nutrition needs vary among individuals and that one-size-fits-all extreme diets rarely provide optimal solutions.

The concept of dietary diversity—consuming a wide variety of foods to ensure adequate nutrient intake—stands in stark contrast to the carnivore diet’s extreme restriction. Research increasingly suggests that dietary diversity, particularly in plant foods, supports a healthy gut microbiome and provides the broad spectrum of nutrients needed for optimal health. Rather than eliminating food groups, focusing on including a variety of minimally processed foods from all food groups typically yields better long-term health outcomes.

Conclusion

The carnivore diet, despite its growing popularity and the enthusiastic claims of its proponents, presents numerous serious health concerns that cannot be overlooked. As this article has explored, the risks span multiple body systems and include both short-term and long-term health implications that should give potential followers pause.

The cardiovascular risks alone—increased LDL cholesterol, higher saturated fat intake, and the elimination of heart-protective plant foods—present significant concerns for long-term heart health. These risks are compounded by the nutritional deficiencies inherent in eliminating all plant foods, particularly the absence of vitamin C, certain minerals, fiber, and thousands of beneficial phytonutrients that play crucial roles in maintaining optimal health and preventing disease.

The digestive system faces particular challenges on the carnivore diet, with the complete absence of fiber potentially leading to constipation, disruption of the gut microbiome, and increased risk of colorectal cancer. Similarly, kidney function may be compromised by the extremely high protein load, with increased risks of kidney stones and gout representing significant concerns. The potential impact on bone health through increased calcium excretion and metabolic acidosis further adds to the list of physiological concerns.

Perhaps most alarming is the increased cancer risk associated with high consumption of red and processed meats, particularly in the absence of the cancer-protective compounds found exclusively in plant foods. The World Health Organization’s classification of processed meats as carcinogenic and red meat as probably carcinogenic underscores the seriousness of this concern.

Beyond these direct health impacts, the carnivore diet’s extreme restrictiveness makes it difficult to sustain long-term for most individuals, while its heavy reliance on animal products raises significant environmental and ethical questions about its broader sustainability.

As nutrition experts like Lisa Marsh and Shannon Haynes emphasize, more balanced approaches that incorporate a variety of foods typically yield better long-term health outcomes while being more sustainable and enjoyable. The Mediterranean diet, moderate low-carbohydrate approaches that include vegetables, or simply focusing on whole, minimally processed foods from all food groups represent healthier alternatives for most individuals.

Before embarking on any extreme dietary pattern, including the carnivore diet, individuals should consult with healthcare professionals who can provide personalized guidance based on individual health status, risk factors, and goals. While short-term weight loss or symptom improvements might occur on the carnivore diet, these potential benefits must be weighed against the substantial evidence suggesting numerous serious health risks over the longer term.

In nutrition, as in many aspects of health, extreme approaches rarely provide optimal solutions. The carnivore diet, representing perhaps the most extreme elimination of plant foods in any popular diet, exemplifies this principle. The overwhelming consensus among nutrition researchers and medical professionals suggests that for most people, a more balanced and inclusive approach to eating will better support long-term health while avoiding the significant risks associated with the carnivore diet.

References

1. Harvard Health Publishing. “What is the carnivore diet?” Harvard Medical School, May 8, 2024.
2. Baylor Scott & White Health. “Meat madness: The risks of the carnivore diet.” September 26, 2024.
3. St. Vincent’s Medical Center. “Is the Carnivore Diet Actually Healthy?” February 19, 2025.
4. World Health Organization, International Agency for Research on Cancer. “IARC Monographs evaluate consumption of red meat and processed meat.”
5. Science. “Reducing food’s environmental impacts through producers and consumers.” J. Poore, T. Nemecek, 2018.