After a confusing debate of sporadically placed comments and tags from an adamant carnivore on social media, I decided to jump into the literature and find out what the science says about this extreme diet protocol because I personally can't imagine or believe that only eating only animal products for the rest of your life is healthy... yet people are claiming it is... even doctors.
So first things first... What is the Carnivore diet?
It's a diet solely of animal products and that's it.
Unlike the Keto Diet that allows some carbs, very minimal but some, the carnivore diet is a zero carb diet. This means no fruit, no vegetables, no sauces, and nothing with even traces of carbs like gum, water flavoring packets, electrolyte powders, etc. An article posted on Cleveland Clinic's website says "The carnivore diet boasts weight loss, improved mood, as well as blood sugar regulation. It was founded on the belief that high-carb diets are the cause of chronic disease." But where is the clinically significant research?
I'll get to that, but first...
What exactly can you eat?
Food included in this diet come from 100% animal products:
For example: Breakfast: Three eggs cooked in butter with a few slices of bacon. Lunch: Rib eye steak. Dinner: Hamburger patties with cheese.
Could you eat this everyday for the rest of your life in pursuit of health?
Do you think this is a 'healthy' diet in the first place?
I was 'advised' to listen to a podcast episode hosted by The Meat Mafia and in this episode they interviewed Dr. Anthony Chaffee who is a neurosurgeon, a nutritional researcher (with no nutritional credentials) and an advocate for the Carnivore Diet. He believes this diet is the optimal human diet when he saw the benefits in his own life and his patients.
He states that plants have natural carcinogens in them and that they're poisonous, yet some humans can survive on plants. He believes that European settlers brought disease to the native lands including gout, obesity and other comorbid conditions that are associated with a general Western diet. He claims that humans were carnivores to begin with using anthropology, fossils and isotope data to back up his claims. He states that humans were once the apex predators in ancient times, yet we do not have the evolutionary history to show or support a physiology that could take down lions, bears and other animals without the use of weapons...
Dr. Chaffee uses 1989 publications from Bruce N. Ames, Ph.D. to support many of his claims advocating for the carnivore diet. Dr. Ames has a Ph.D. in biochemistry and published over 500 articles, the last of which occurred in 2015. I'd consider this outdated and unsupported research. Generally, medical professionals utilize research within the last 5 years to support evidenced based claims. Regardless, he's done amazing work in the cancer research and anti-aging fields. He was actually interviewed on the Live Longer World Podcast Feb 1, 2022 where he states that there are 35-40 essential vitamins and minerals we need in our diet to support a healthy metabolism, and we get those essential nutrients from green vegetables, nuts, and "all sorts of things in a varied diet so you get everything." Sounds like Dr. Ames has changed his tune since 1989 and Dr. Chaffee needs to get updated with current research and what's in practice now... that's just my professional opinion...
Anyways, let's get back to the Meat Mafia Podcast interview...
The next piece of supporting literature Dr. Chaffee uses is the work of a 19th century physician, Dr. James Salisbury of the brand Salisbury Steak. "The Salisbury Steak actually has its beginnings as a proposed cure for digestive illness during the Civil War." Digestive illness killed many soldiers during the Civil War and Dr. Salisbury believed "a diet rich in beefsteak and coffee was one suggested cure." He believed vegetables and starchy foods were responsible for digestive distress, heart disease, tumors, mental illness and tuberculosis. Based on human dentition, he believes that we were meant to eat meat and sought to limit carbohydrate containing foods and fats to only 1/3 of the diet. (1, 2). When I look at the teeth of tigers, lions and bears, I don't really see a resemblance with human teeth... Our teeth look more like a chimpanzee's teeth, with canine teeth for tougher foods and flat box-shaped teeth for softer foods. A chimps diet consistent mainly of nuts, seeds, beans/legumes and insects. Take a look at some dentition examples here:
Dr. Chaffee also cites dietary recommendations from a famous 1928 explorer named VILHJALMUR STEFANSSON who was a proponent of an all-meat, Inuit diet. After his exploration ventures, he checked into New York’s Bellevue Hospital for a year-long trial to be studied by physicians while on a meat-only Inuit diet, the study was funded by the Institute of American Meat Packers (good to know). Doctors reported that he did not suffer from elevated blood pressure or kidney issues but Stefansson noted the importance of having fat in this diet and that it was also lacking calcium.
It's important for me to bring awareness around the process of gluconeogenesis which is a metabolic process that uses non-carbohydrate substrates to make glucose in the body. Our body does this when there is limited carbohydrate consumption, lack of glycogen storage, and/or when the body is in a starved, stressed state. Which means, the body will utilize this process if someone is consuming only meat because they brain and body needs glucose to survive... glad we cleared that up... moving on...
In the podcast, Dr. Chaffee never uses CURRENT research to support his carnivore diet claims which is problematic for the medical and research communities. He also bashes the USDA saying their nutrition recommendations "destroyed the health of humanity." I'm not saying the governmental nutrition recommendations we have are perfect models of health but they definitely didn't destroy the health of humanity, if anything marketing corporations and ultra-processed foods did. He also states that the documentaries "Games Changers" and "What the Health" have done a lot of harm to those who have watched them. I wonder what he would think of the documentary "Cowspirarcy" and "Seaspiracy".
There were so many other statements and claims that Dr. Chaffee makes in the podcast that are just wrong; like how consumption of cholesterol from food is essential for health when it's not, our liver makes the cholesterol we need on it's own; or how old-school bodybuilders like Arnold Schwarzenegger would eat only eggs and steak to prep for bodybuilding competitions which is also wrong; bodybuilders consume a high amount of protein but also balance that with minimal carbs and fats to lose weight. Then they increase carbs or "carb up" for show day so glycogen gets into the muscles and they get that pumped look for stage.
Dr. Chaffee also uses anecdotal evidence to support the carnivore diet- many people have claimed and self-reported that this meat-only diet has reversed, healed and cured various aliments like rheumatoid arthritis, type 1 and type 2 diabetes, GI conditions and auto-immune disorders. but the gold standard scientific research and publications are not there.
Let's address what a carnivore diet would do to your gut health, because a healthy gut is paramount of overall health...
Unfortunately, there's no scientific literature on carnivore diet in conjunction with gut health but there is some talk of the keto diet and gut health. To review, the keto diet severely limits carbohydrates with a focus on fats and protein as your main dietary intake. "Generally, popular ketogenic resources suggest an average of 70-80% fat from total daily calories, 5-10% carbohydrate, and 10-20% protein." - SOURCE.
Let me take you back to basic anatomy and physiology:
When we refer to "the gut" we mainly mean the small and large intestine which houses the majority of the microbiome but it can also encompass accessory organs including the stomach, gall bladder, liver and pancreas. The majority of digestion occurs in the stomach (no surprise) while the majority of nutrient absorption occurs in the small intestine and the majority of water absorption and stool formation occurs in the large intestine.
Your individualized and unique microbiota in your gut is diverse (well it should be) and feeds off of the things we otherwise, could not digest, mainly fibrous components of plants (includes fruits and veggies), seeds, nuts and grains- carbohydrate containing foods. So yea, if you eliminate all of that, then you aren't feeding your microbiome and thus 'resting the gut' so to speak. In a clinical setting, we don't rest the gut unless someone just had gastric surgery and/or intestinal resections, has a GI bleed of some sort or is experiencing extreme distention from some unknown reason. From a functional medicine standpoint, I can see gut rest being beneficial for those that have chronic gut issues (think SIBO, leaky gut, H. pylori, IBS), gastroparesis, dumping syndrome, extreme bloating, food allergies and sensitivities, etc. but not as a life-long protocol as suggested by carnivore diet advocates.
By not feeding the microbiome fibrous foods (yes, carbohydrate containing foods) we are impacting the gut's ability to produce short-chain fatty acids.
wait! 'fatty acids' made from carbohydrates? what?!
"Short-chain fatty acids (SCFAs) are the main metabolites produced by the microbiota in the large intestine through the anaerobic fermentation of indigestible polysaccharides such as dietary ant starch." - SOURCE. The three SCFAs produced by the gut from fermentation of dietary fibrous foods are propionate, butyrate, and acetate. The picture below highlights the SCFAs and their byproducts affects on the rest of the body and how much other systems rely on these products for their functionality.
The production of SCFAs, or the lack thereof, has a profound impact on our brain health and studies in animals and humans show that "gut microbiota dysbiosis has been implicated in behavioral and neurologic pathologies, such as depression, Alzheimer's and Parkinson's diseases and autism spectrum disorder." - SOURCE.
Acetate is important for cellular energy production, lipid synthesis and protein chemistry in the body. Butyrate is important for intestinal integrity and structure. Propionate is important for lowering carcinogenic compounds in the body, lowers cholesterol levels in the blood and lowers lipogenesis. Without a well fed gut from fibrous foods (which is eliminated in the carnivore diet), you're gut health is at risk which can impact many processes in the rest of the body.
There's a great podcast addressing how the ketogenic diet affects one's gut health and I'd believe that a carnivore diet would have a similar, if not more impactful, outcome. You can listen to that HERE on apple podcast.
As an RD, another alarming thing about this diet (among many) is how restrictive it is, which ultimately makes it unsustainable and, I would think, not appealing as something you would want to eat everyday for the rest of your life... Don't get me wrong, I love bacon and my foods cooked in butter, but only that? To each their own I guess. But again, what does the literature say?
Let's dive deeper into the scientific literature and what the doctors are saying about this diet... Because doctors are always right and know everything about nutrition, more than an RD... right?
Two names continue to surface for me during my search: Dr. Shawn Baker, MD. and Dr. Paul Saladino AKA the 'Carnivore MD" who claims plants are not your friend and that an animal-based diet is the way to go.
The first reg flag for me when looking at Dr. Saladino's website is he mentions consuming an "animal-based diet" which lends one to believe that it's not a 100% animal only, carnivore diet... I dug further...
I did the animal based calculator on his website and among the animal products recommended, it also recommends 116g of carbohydrates from honey and fruit... soooo I'm going to go ahead and eliminate Mr. Carnivore MD from my research since he seems a bit hypocritical here as someone toting the carnivore diet.
Let's take a look at Dr. Shawn Baker. He is an orthopedic surgeon, author, athlete, father and a self-proclaimed "lead authority on medical nutrition therapy." FYI, Medical Nutrition Therapy (MNT) is what dietitians are trained in; it's their primary expertise and what they've spent their educational career learning; when dietitians get their licensure, it's so they can practice MNT. Physicians and surgeons have one course and sometimes only one class in general nutrition.
Just had to make that clarification...
One would think that your LinkedIn profile would be the best way to showcase your achievements so I checked out Dr. Baker's educational background on his LinkedIn profile. He received his undergraduate B.A. degree in 1989 and then in 2007 he graduated with honors from Texas Tech University with his MD credential... That's it; not even a nutrition certification. He was a lead orthopedic surgeon at Rust Medical Center in New Mexico for four and half years ending in 2015, then wrote "The Carnivore Diet" book in 2019.
In a 2017 YouTube video, Shawn Baker addresses "what happened to my medical license" and it sounds like the hospital he was working at initiated a peer-review process of him as a physician because of the dietary interventions and handouts he was giving to patients (not approved by the hospital). He was using a Carnivore diet protocol to steer patients away from orthopedic surgeries. Upon review, they found multiple surgeries he performed that were not in congruent with hospital policy, stating he was not performing the proper procedure. Shawn Baker claims that some of the people reviewing his clinical reports were semi-retired, likely implying that they should not have been reviewing the reports and patients reported positive outcomes at 6-month post-op . He did not have a malpractice lawsuit but his medical license was suspended after a 2 year process of review with the option of reinstating it. He did in fact, restore his license a year later.
In another YouTube video he does state that he advocates for a carnivore diet, meat-based diet, keto diet, low carb/high fat diet and even a plant-based diet in order to prevent the need for medications and procedures. As a registered dietitian and someone trained to provide MNT to their patients, I'm all for different diet protocols to alleviate and eliminate various conditions, diseases and aliments. And given this state he made, sounds like he is too.
So now we have evidence that both of these doctors that claim to be carnivore diet advocates, are recommending carbohydrates in their protocols, whether that's 116g coming from honey and fruit or a Atkins style or plant-based diet approach.
I feel like this article could be done here since the main doctors advocating for the carnivore diet don't seem to be solely adherent to 'animal only' foods. BUT I said I'd look into the scientific literature so here we go...
STUDY 1: PMID: 34934897 Dec. 2021
"Little is known about the health effects and tolerability of carnivore diet, and concerns for nutrient deficiencies and cardiovascular disease risk have been raised."
Researchers conducted a social media survey over 4 months among adults self-identifying as consuming a carnivore diet. Survey questions looked at motivation for the diet, dietary intake patterns, symptoms suggestive of nutritional deficiencies or other adverse effects, satisfaction, prior and current health conditions, anthropometrics, and laboratory data.
Total of 2029 respondents: All participants had to have been practicing a carnivore diet for at least 6 months.
Participants reported being on the carnivore diet ranging from 6 to 337 months, average of 14 months.
Average age: 44, ranging from 18-85 years old: 67% male and 33% female.
Main motivation: health reasons (93%).
Red meat consumption was reported daily by 85%.
Under 10% reported consuming vegetables, fruits or grains more than monthly.
37% denied vitamin supplement use, meaning 63% are supplementing their diet. (Because more than half of the population in this study reported using vitamin supplements to support their diet, we can deduce that these individuals likely feel the carnivore diet alone does not provide them with all their essentials nutrients)
Prevalence of adverse symptoms was low (<1% to 5.5%). Symptoms included gastrointestinal (3.1%–5.5%), muscular (0.3%–4.0%), and dermatologic (0.1%–1.9%).
95% reported improvements in overall health.
66-91% reported improvements in well-being.
48-98% reported improvements in various medical conditions.
Some participants reported consuming alcohol which is primarily made up of sugar and not allowed on the carnivore diet.
LDL was markedly elevated with an average of 172 mg/dL. (indicating heart and vascular concerns)
HDL and triglycerides were in their optimal range.
Total cholesterol was elevated with an average of 256. (again, indicating heart and vascular concerns)
Those with diabetes reported reductions in BMI of 1.4-7.2 points, HBA1c up to 1.7% and diabetes medication use by 84-100% (not surprising since they're eating a very low carb diet).
89% never consumed legumes
87% never consumed breaded and fried fast food meats
81% never consumed candy & milk chocolate
80% never used multivitamin supplements.
79% never consumed grains
78% never consumed sugar
75% never ate desserts
74% never consumed honey
74% never consumed starchy vegetables
69% never consumed non-starchy vegetables
66% never consumed fruit
65% never consumed non-calorie sweeteners
So, none of them were 100% adherent to a strict carnivore diet... do we see a disconnect then with the dogmatic narrative that is typically given when a carnivore recommends this diet? This makes me believe that these people are practicing a keto diet...
can I see urine analyses please? The authors concluded that "adults consuming a carnivore diet experienced few adverse effects and instead reported health benefits and high satisfaction. Cardiovascular disease risk factors were variably affected. The generalizability of these findings and the long-term effects of this dietary pattern require further study."
But were they really consuming a carnivore diet when none of them could say they have a 100% animal-only diet?
I'd like to note that Shawn Baker was involved in the development of this study as well as Travis Statham, neither of which had any medical or nutritional credentials attached to their names in this article at the time.
An important thing to note is all of the information used in this study was self-reported, including the blood work data! As a public health professional, I'd be remised not to inform you that when data is self-reported, especially from those engaging in extreme, unorthodox, and typically unaccepted practices, they'll typically self-report in favor of their narrative. This is called self-report bias.
"Recalling what exactly one eats in a week, month or year is notoriously difficult. And there is no way to objectively verify the accuracy of self-reported eating habits and health outcomes." - SOURCE Let's look at another study...
Well let's try... As I continued my search for the gold-standard in research, randomized controlled trials, I could not find anything. I then stumbled across an article by Mark Sisson who is an avid keto promoter and even wrote a book all about the keto diet called Keto for Life; he wrote about the carnivore diet and stated "Unfortunately, I can’t find any randomized controlled trials looking at carnivore for any health issue. There are a small number of published case studies, and Shawn Baker is currently trying to crowdfund some research [the article I just reviewed above]. Otherwise, we have to rely on anecdotes and inferences from studies on other related diets (low-carb, high-protein, keto, low-FODMAP, and so on). Anecdotes are important, but they’ll never replace well-designed empirical studies."
Again, I say in regards to scientific evidence to support a carnivore diet, we don't have it. As far as case studies and anecdotal evidence to support a modified-carnivore diet, we have that in one study. And I say 'modified-carnivore' because no one was in fact practicing the carnivore diet 100%.
And I won't discredit someone's lived experiences. The vast majority of the people in the study reported improvements in their health and I know people report large weight loss on this diet as well (as if that should even be the main focus of any diet, but that conversation is for another time). The fact that there are a decent amount of people practicing this diet, warrants further research, and research that can give substantial non-bias information in the form of RCTs, cohort studies or hell, even cross sectional studies. But it will be hard to ethically prescribe this diet in quality research since ethically, telling someone to eat a carnivore diet isn't in fact, ethical. So who knows if we will ever get the research needed to support a diet as extreme as this.
To conclude (yes, finally), I'm not saying that the Western Diet of refined carbs like bagels, donuts, cakes, cookies, brownies, fried and ultra-processed foods are nutritious and should be apart of everyone's diet (there are definite mental benefits to eating cookies though), but I am saying that plants, grains, legumes, fruits and vegetables, nuts and seeds have a place in a general healthful diet. Look at the centenarian blue-zone diets! These people live well into their 100s and their diet consists 95-100% of plants and only consume meat 5 times a month! What would Dr. Chaffee, Dr. Baker, and the others have to say about that?!
Limiting your carb intake can be helpful for managing various chronic illnesses as well but it's not always necessary. This is why working with a trusted, educated dietitian (like myself) can be so helpful in assessing the type of diet and nutritional protocol you need for your body!
Ultimately, if you can find a diet, program or protocol that is easy for you to maintain and sustain in your life, that doesn't limit you in social situations, celebrations, holidays, etc., that at least meets all the RDA for vitamins, minerals and macronutrients, that adds to your life and you health instead of takes away from it, then do that.
I hope you enjoyed this blog post! Feel free to comment and/or share this with a friend who you think would be interested! Screenshot and share your favorite part on social media and tag me @alexis_fitco!
If you're curious to know what the RDA for vitamins and minerals and the Acceptable Macronutrient Distribution Range (AMDR) are for general healthy adults, check out the photos below:
keep in mind, these are used as reference ranges for gen pop, if you're curious to know what exactly your intake should be, sign up for a discovery call with me today and let's chat about your nutritional and wellness goals!