I find the Carnivore Diet one of the most absurd trends I’ve encountered. For those unfamiliar, this diet involves consuming almost exclusively animal-based foods—such as meat, lard, butter, eggs, and milk—while eliminating plant-based options, with rare exceptions like olive oil. If eliminating fruits and vegetables seems absurd and potentially harmful, congratulations, you are correct.
Influencers continue to push the limits of reason. One ate an entire bar of butter as a “healthy snack” and encouraged followers to do the same. Another created a “carnivore Oreo” made with meat flour, date syrup, honey, tallow, and goat milk powder. Personally, I’d take my chances with the ultra-processed version—it actually seems healthier.
Proponents of this diet follow the same pseudoscientific reasoning we've encountered countless times:
- Relying on anecdotal evidence.
- Cherry-picking favorable studies.
- Resorting to the naturalistic fallacy, claiming that the human body was designed to consume natural fats, such as those from animal origin, and non-transgenic vegetable oils. This last statement is interesting, considering that the body cannot distinguish whether a product is synthetic or natural once ingested.
- Promoting the diet as a cure-all for various health issues.
The Birth of the Carnivore Diet
Determining the origin of the "carnivore diet" is challenging, but one of its earliest proponents was Scottish military surgeon John Rollo. In 1797, Rollo published an article describing his treatment of Captain Meredith, a patient with diabetes mellitus. Meredith experienced severe thirst and frequent vomiting and urinated over 11 liters of sweet-tasting urine daily. Rollo’s experimental treatment included an animal-based diet, which led to some initial improvement.
Based on this case and another similar one, Rollo drew several incorrect conclusions: he believed diabetes mellitus to be a stomach disease, proposing that a diet consisting entirely of animal-based foods combined with the use of emetics and narcotics should be the primary therapeutic approach.
A century later, Italian doctor Arnaldo Cantani expanded on this idea, theorizing in 1872 that diabetes was a “disease of material metabolism” marked by the accumulation of sugar. Cantani hypothesized that sugar, unable to integrate into the body’s metabolism, became a “useless” substance in diabetics, which he named “paraglucoso”
Based on experimental results, he recommended an “absolute carnivorous, high-fat diet,” which gained widespread adoption among doctors. Today, we understand that diabetes mellitus is a metabolic disease characterized by high blood sugar levels, typically caused by problems in insulin production or action.
A few years after Cantani's contributions, American doctor James Henry Salisbury (famous for the eponymous steak and his pioneering work in germ theory) advocated for a diet primarily composed of animal-based foods to address various health issues. Salisbury justified his recommendations with the flawed belief that humans are, by nature, two-thirds carnivores and one-third herbivores, arguing that their diet should reflect this “balance.”
The ‘New’ Carnivore Diet
Repeating the mistakes of his predecessors, who used anecdotal experiences to "prove" their hypotheses, orthopedic doctor and athlete Shawn Baker has become a leading figure in the carnivore diet movement. His rise to fame began with an appearance on the Joe Rogan Experience, where he persuaded Rogan to experiment with the diet.
Baker’s book, The Carnivore Diet, further solidified his position as a guru, detailing his life story and the events that inspired his diet. He conducted an online poll of his 90-day carnivore diet, with hundreds of volunteers reporting no deaths, scurvy, or significant health issues, and many participants reported weight loss and improvements in digestion, joint health, and sleep. However, nutritionists raised concerns about the potential risks of the diet, citing possible links to cardiovascular disease and colon cancer.
Baker countered these claims by stating that such professionals ignored clear evidence suggesting that populations following meat-based diets supposedly remain free of these conditions. He accurately criticized certain aspects of how epidemiological research in nutrition is conducted but delved into conspiracy theories and avoided scrutinizing the flaws in his research methods.
“Why doesn’t every wild animal that eats meat suffer from the chronic diseases modern humans face? How can a food source consumed for millions of years suddenly become toxic to us, while all animals remain unaffected?”
- Shawn Baker
Beyond epidemiological issues, Baker argues that biological factors justify the carnivore diet. He points out that humans have a highly acidic stomach, which he suggests evolved to handle pathogens in food. Additionally, he references indigenous African hunters eating meat from lion-killed prey to support the idea that humans adapted to consuming potentially contaminated food.
This argument oversimplifies the issue by presenting a false dichotomy, implying that meat must be either entirely beneficial or toxic, ignoring the possibility of nuanced effects. It also appeals to tradition, assuming long-term human consumption automatically equates to safety or health benefits.
Why haven’t I didn’t directly reference any scientific studies cited by Baker? Because there is none. His evidence comes from unreviewed sources such as books, websites, and videos, or cherry-picked studies of animal experiments, in vitro tests, or observational studies —the same methodologies he harshly criticizes elsewhere.
Current Evidence for the Carnivore Diet
Scientific studies on the carnivore diet remain scarce, primarily consisting of case reports and self-reported online surveys.
In 2021, proponents of the carnivore diet began citing a supposed study claiming to demonstrate its benefits. The study explored participants' motivations and self-reported health outcomes after following the diet for at least six months. Data was collected through an online survey, with participants recruited from social media groups like the “World Carnivore Tribe” on Facebook.
Participants reported improvements in various medical conditions, overall health, and aspects such as sleep quality, strength, and focus.
The study design
- Recruited from a biased sample
- Failed to determine whether the correlations between the diet and the reported benefits were statistically significant or merely coincidental — an outcome I find likely.
- The findings were self-reported, without objective measurements such as clinical exams, nutritional assessments, or health-related biomarkers.
- Dietary consumption and frequency data were also self-reported, leaving the findings vulnerable to recall and reporting biases.
The study's severe limitations reduce it to little more than biased propaganda when cited as evidence for the carnivore diet's benefits.
Beyond this work with its limited conclusions, the carnivore diet was also investigated in a case report study.
In this study, the authors reported successfully treating 10 patients with inflammatory bowel disease, a severe small intestine inflammation, using a ketogenic or carnivore diet.
Participants were selected based on prior knowledge of their cases or responses to a Twitter post. Interested individuals were interviewed and asked to provide medical documentation confirming their IBD diagnoses.
In one case, TH, a 62-year-old man with Crohn's disease, struggled with symptoms like gas, bloating, and loose stools since age 28 despite conventional treatments. After trying various diets, including gluten-free and ketogenic, he adopted a carnivorous diet at age 57, leading to a 99% improvement in symptoms and complete pain relief over a year.
The authors propose two hypotheses for the therapeutic effects:
- Production of ketone bodies [1].
- Elimination of problematic foods through strict dietary restrictions.
However, the study had selection bias, as it only included patients who reported positive outcomes and anecdotal experience, which is weak evidence meant more to inspire further research than draw definitive conclusions.
Meat: To Eat or Not to Eat?
To avoid falling into the false dichotomy of categorizing foods as "good" or "bad," it's important to note that red meat, especially cuts high in saturated fats, should be limited. However, this does not mean it should be completely excluded; it should be consumed in moderation. I believe the best synthesis of the topic is found in Novella's article, "Skeptical of the Carnivore Diet":
“The carnivore diet is yet another diet fad based on eliminating food categories considered 'bad' and restricting them to 'good' categories. The theoretical justification for this approach is deeply flawed, and there is no evidence to support it. Moreover, several lines of evidence suggest that restricting your diet exclusively to meat and eggs can be harmful to your health. Decades of research on diet and health lead us to a relatively simple conclusion: consume a varied diet rich in fruits and vegetables, avoid excess calories, and practice moderation.”
The Carnivore Diet might appeal to those craving simplicity or a contrarian narrative, but its foundation crumbles under the weight of evidence-based nutrition. Decades of research consistently show that balanced diets rich in fruits, vegetables, and whole grains support heart health and longevity. While its proponents revel in anecdotes and conspiracies, the real question isn’t “Is this sustainable?” but rather, “Is this survivable?” When it comes to health, the key is moderation and variety rather than extremism.
[1] Ketone bodies are the products of fatty acid metabolism that occur when the body can no longer use glucose as an energy source. This typically happens during prolonged fasting or following a diet with low or no carbohydrates, such as a ketogenic diet.
