The carnivore diet, an extreme version of low-carb eating, has gained traction on social media, showcasing plates piled high with meat, devoid of any plant-based foods. Proponents tout benefits like rapid weight loss, clearer skin, reduced bloating, and even remission of autoimmune conditions, although these claims lack rigorous clinical validation. Some view it as a return to ancestral eating patterns, mimicking Paleolithic hunters. However, the modern industrial meat supply differs significantly from that idealized past.
The Carnivore Diet: A Statement?
Sociologist Richard Twine suggests the carnivore diet's popularity reflects a backlash against widespread calls for dietary change. Loading plates with meat becomes a statement, rejecting sustainability, public health advice, and mainstream ideas of responsible eating. This raises the question: Is the carnivore diet a biologically sound path to health or merely a primal-themed trend?
How the Carnivore Diet Impacts Your Gut
Many individuals report reduced bloating, less gas, and a trimmer waistline upon starting the carnivore diet. However, the absence of long-term clinical trials leaves most health claims speculative.
When carbohydrates are eliminated, the body initially uses glycogen stores for energy. As these stores deplete, water is released, leading to rapid water weight loss. Subsequently, the body enters ketosis, using fat as its primary fuel source. Ketosis suppresses hunger hormones and increases satiety signals, explaining why many feel lighter and less hungry in the initial weeks.
Gastroenterologist Wendi LeBrett notes that some individuals on the carnivore diet report reduced bloating and gas, potentially due to the absence of fermentable fibers, especially high-FODMAP foods. A 2022 study demonstrated that a low-FODMAP diet significantly reduced abdominal pain, bloating, and stool irregularities in adults with irritable bowel syndrome. Similar relief can be achieved through a low-FODMAP diet without completely eliminating plant-based foods.
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However, long-term fiber removal can reduce the body’s tolerance to it. Nutrition scientist Emily Prpa explains that the gut may overreact when plant-based foods are reintroduced, leading to increased symptoms and reinforcing restrictive habits. Fiber is crucial for long-term health, protecting against heart disease, cancer, diabetes, and promoting longevity and cognitive health. A 2023 review found that high fiber intake reduces overall cancer risk by up to 22 percent, with a significant protective effect against colorectal cancer. Eliminating fiber removes a key defense for both body and mind.
What Your Body Misses on a Meat-Only Diet
Beyond digestion, the absence of plants leads to nutrient losses. Fruits, vegetables, and grains provide essential nutrients like vitamin C, antioxidants, and phytonutrients, which combat inflammation and support long-term health.
The high protein intake in carnivore diets places extra strain on the liver and kidneys. The liver must convert excess nitrogen from protein into urea, which the kidneys filter out, potentially increasing the risk of kidney stones and long-term organ stress.
Prpa also highlights the potential impact on brain health. Diets rich in fiber from plant foods, like the Mediterranean diet, are linked to better mood, lower depression risk, and improved brain health. Studies show that following the Mediterranean diet reduces depression risk by about 19 percent, and a five-gram increase in dietary fiber corresponds to a 5 percent reduction in depression risk.
Potential Heart Health Risks
Cardiologists caution against diets centered on red and processed meats, due to their high saturated fat and cholesterol content. These components can elevate LDL ("bad") cholesterol levels, a major risk factor for cardiovascular disease. A 2021 study of over 180,000 participants found that high red meat consumption was associated with a 20 percent increase in cardiovascular disease risk, a 53 percent rise in heart disease, and more than double the risk of stroke-related mortality.
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Prpa notes that the absence of fiber eliminates a natural tool for lowering LDL, as soluble fiber binds cholesterol in the gut and helps remove it from circulation. Given that LDL is a key driver of heart disease, the long-term cardiovascular risks of the carnivore diet are a significant concern.
The Appeal of Elimination Diets
Despite these risks, the carnivore diet attracts individuals seeking relief from chronic digestive issues, food intolerances, or autoimmune symptoms. Its simplicity and elimination-style approach are appealing. Many hope for quick fixes or a "reset" of their system by cutting out foods.
In the short term, it can be effective, especially for those who previously consumed large amounts of ultra-processed foods.
Case Studies: Carnivore Diet and IBD
A case series reported on 10 patients with inflammatory bowel disease (IBD) who responded positively to ketogenic or carnivore diets. These patients had ulcerative colitis (UC) or Crohn’s disease and experienced clinical improvements with diets consisting mostly of meat, eggs, and animal fats.
One patient, TH, diagnosed with Crohn’s disease at age 30, experienced persistent symptoms despite various medications. At age 57, he adopted a fully carnivorous diet, including mostly beef and eggs, with minimal dairy and black coffee. His symptoms improved significantly, and lab results showed positive changes.
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Another patient, AN, diagnosed with ulcerative proctosigmoiditis at age 25, transitioned to a carnivore-ketogenic diet consisting of mostly red meat, eggs, and small amounts of low-carbohydrate plant matter. He experienced an improvement in symptoms, eliminated loose and bloody stools, and discontinued medication completely.
Patient OS, diagnosed with Crohn’s disease at age 20, trialed a carnivore diet after a non-blood relative had success with it. Within five months, her calprotectin levels dropped significantly, and she reported no symptoms while on the diet.
Patient IA, diagnosed with UC at age 30, committed to a meat-only diet and reported that all his symptoms subsided within 4-5 days. He later added back eggs and raw dairy, with continued absence of IBD symptoms.
Patient MI, diagnosed with UC at age 18, found that a carnivore-ketogenic diet eliminated his residual symptoms, and he discontinued mesalamine without issue.
Patient NE, diagnosed with Crohn’s at age 12, tried a carnivore diet after years of suffering with the disease. He found lasting symptom relief.
Diverticulitis and the Carnivore Diet
Diverticulitis, a digestive condition causing abdominal pain and bloating, may be affected by dietary changes. A 2020 article found that higher meat consumption was associated with a mild increase in the risk of developing acute diverticulitis, especially with unprocessed red meat. Poultry consumption did not appear to increase this risk. Therefore, a carnivore diet high in red meat may increase the risk of diverticulitis or worsen existing symptoms. More research is needed to determine if a carnivore diet focusing on white meat is suitable for people with diverticulitis.
The Gut Microbiome and the Carnivore Diet
The carnivore diet is often promoted as a solution for bloating and improving gut health. While some individuals report positive results, it's crucial to understand the complexities of the gut microbiome.
The American Gut Project, one of the largest gut microbiota studies, found that the diversity of plants in the diet is the most powerful determinant of a healthy gut microbiome. Participants who ate more than 30 different plant types per week had more diverse gut microbiomes than those who ate 10 or fewer. Prebiotic fiber, found in plants, feeds beneficial gut bacteria, which release short-chain fatty acids (SCFAs) that have healing effects throughout the body.
However, plants can also cause bloating and gut problems for individuals with underlying gut pathologies or conditions like IBD, SIBO, candida, or severe dysbiosis. In these cases, the carnivore diet may provide relief by eliminating fermentable carbohydrates.
Switching to an all-meat diet can rapidly alter the gut microbiota, increasing bile-tolerant organisms and decreasing microbes that metabolize plant fibers.
The Dark Side of Long-Term Carnivory
Long-term, the carnivore diet may lead to an imbalanced gut microbiome if underlying gut pathologies are not addressed. It's crucial to increase microbial diversity, weed out pathogens, and seed in beneficial bacteria through prebiotics and probiotics.
Research does not support long-term benefits from the carnivore diet for improved gut health and bloating symptoms. A study comparing a carnivore diet to a plant-based diet over five days found that the carnivore diet increased inflammatory bacteria and decreased anti-inflammatory bacteria. It also led to increased growth of bacteria associated with inflammatory bowel diseases, lower levels of SCFAs, and increased antibiotic resistance in the gut.
Long-term restrictive diets can also be detrimental due to nutrient deficiencies. The carnivore diet may lack essential micronutrients like vitamin C, vitamin E, vitamin K2, calcium, manganese, and magnesium.
Furthermore, long-term all-meat consumption can tax the liver and detoxification pathways. The liver starts to make glucose from protein via gluconeogenesis, creating nitrogenous waste that must be processed. Consuming more than 35 to 40 percent of total calories as protein can overwhelm the liver and the body’s natural cleansing cycle.