The carnivore diet gives us the ripped-torso new kid on the block, surviving on beef and water with urine strips always at hand to be sure he's still 'in keto', writes MedicalBrief 's Alastair McAlpine, in his Digital Clubbing column.
In the polarised world of nutrition, it’s difficult for the layperson to know where to turn. Depending on where you look, you’ll see vegans, vegetarians, low-carbers, paleos, intermittent fasters. All claiming that their way, and their way alone, will be the panacea for all your health problems. Now there’s new kid on the block. Wearing a tight vest to accentuate a ripped torso, this one embodies the idea of the strong alpha-male who smirks at the folly of modern doctors and their Big Pharma conflicts, claims his favourite vegetable is pork, and has urine strips on hand at all times just to make sure he’s still ‘in keto’. He is the carnivore, surviving on beef and water (with the odd whisky because we all have to let our hair down). Laughing at the vegans and their weak, animal-loving ways, he is the ultimate rebel. But is there any good science behind the carnivore diet? What are the long-term effects on health? Is it a sustainable diet for the planet and for its adherents?
The idea behind the carnivore diet is remarkably simple: if carbs are bad, and low carb is good, then surely zero carb is best? Although relatively low in carbohydrates, vegetables and fruit do contain them, as do dairy products and sauces. While there is no strict definition of what constitutes the carnivore diet, it essentially involves removing all non-meat foods from your plate. Many carnivores will use some butter to cook and will eat eggs and cheese. At its most extreme, however, it is a diet of simply beef and water.
Adherents claim that this is how early ‘paleo’ man used to eat, and is in keeping with our basic physiology. The moment we started to eat meat, they claim, is when our brains expanded dramatically, and we leap-frogged up the food chain to our current position as apex predator. Why would we want to deny this and start eating veggies again? Lions, after all, don’t eat salad, they reason. Human evolutionary biology, however, clearly shows that we are obligate omnivores,1 with the capacity to survive on a broad diet involving multiple food groups. Indeed, analysis of the teeth of our distant ancestors reveals that grains were an important staple of our diet.2 Clearly, our culinary history is much more complex than the carnivores make it out to be.
The pioneer the carnivore diet is often assumed to be Dr Shawn Baker. Nicknamed ‘King of the Carnivores’, a title he embraces, Baker is a US-based orthopaedic surgeon who became a full carnivore in 2017 and has amassed a major following on social media. He has appeared on the popular Joe Rogan podcast, and runs the website ‘Meatheals.com’, which is full of testimonials to the power of the ‘carnivore way’. For a low (low!) fee of $190/h, you can have a one-on-one consult with the man himself. He had his medical license revoked in 2017 for “failure to report adverse action taken by a healthcare entity and incompetence to practice as a licensee,” but has subsequently been reinstated earlier this year. His social media is replete with profanity-laden outbursts against vegans, whom he calls ‘sacks of sh*t’, and ‘suffering from a mental illness.’
The diet also received a lot of publicity when the (in)famous philosopher, Jordan Peterson, and his daughter, Mikaila, became enthusiastic proponents. Mikaila, in particular, has claimed that the diet cured her rheumatoid arthritis, depression, and sleeping problems. Not one to let a silly thing like a lack of medical or dietetics training hold her back, she too offers online consultations. When not expounding on lobsters and social hierarchies, Jordan also believes the diet helped him to lose weight and beat his depression.
Depending on what you read, the carnivore diet will: help you lose weight, fix your arthritis, eliminate all your autoimmune troubles, cure your depression, and make your skin invulnerable to the sun (not kidding). So, what of the evidence? Well, quite simply, there is none. That is, there are no studies on PubMed that look at the effects of the carnivore diet on humans. As a result, we need to do some extrapolation. First of all, the benefits of eating fruit and vegetables have been well described. Large systematic reviews have shown that an increased intake (400g/d or 5 small portions) is associated with a lower risk of all-cause mortality, particularly cardiovascular mortality.3-5 There is also no compelling data that fruit and veg is bad for you, and most of us don’t eat enough of the stuff anyway. So, who would possibly advocate against eating it?
Enter the UK’s Zoe Harcombe, a favourite of the low carb community, and someone who promotes the demonstrably-bogus idea that the reason you have hunger pangs is because of fungal overgrowth in your gut (The cure for which, of course, is the patented ‘Harcombe Diet’, available for $20 through Amazon). She claims the ‘5-a-day’ campaign initiated by the World Health Organisation (WHO), encouraging people to eat at least 5 small servings of fruit and veg per day, has no scientific evidence and was primarily cooked up by those dastardly fruit companies to trick us all into eating more apples. It’s perplexing because I don’t think anyone really believes folk are unhealthy and obese from eating too many green beans or bananas.*
Then there’s the issue of fibre, which is almost completely lacking in the carnivore diet. The evidence for its benefit in humans is robust. A recent meta-analysis published in the Lancet echoes others that have shown that increased fibre consumption is strongly associated with lower cardiovascular, diabetes, stroke, and colon cancer risks.6-8 Like vegetables, most of us don’t eat enough of it, and there is no evidence that fibre is unhealthy, so why anyone would want to eliminate it from their diet is unclear.
And what about scurvy? The indications are that the carnivore diet is not particularly full of micronutrients, such as vitamin C. Interestingly, while scurvy has been described in case reports,9,10 it doesn’t seem to be common to most carnivores. Baker’s explanation on the Rogan podcast (11:47) is that ‘a molecule of glucose and a molecule of vitamin C are almost identical and compete for the same transporters’. Presumably, the presence of less glucose means less vitamin C is required. Now this claim is a bit like saying, ‘A motor car and pedestrian are almost identical and compete for the same road space’. They aren’t and they don’t. But scientific plausibility is not a strong suit of the carnivores.
There are issues beyond just health, however. For most of us, food is more than simply sustenance to power our bodies until the next meal. Sharing food with others is one of our most cherished social interactions, across cultures and religions. People use meals to talk, to bond, to share, to laugh, to nourish. When someone adopts such an extreme eating position, one necessarily excludes oneself from this socializing ritual. The mental costs of such an exclusion were beautifully explained by Alan Levinovitz here. (https://tonic.vice.com/en_us/article/7xqqyz/carnivore-diet-appeal)
Food itself is also a source of immense joy for many of us: the bitter bite of good coffee in the morning, a fresh peach in spring, warm sourdough with a delicious paella, a warm bowl of bolognaise pasta, cooling ice cream on a hot summer’s day. It makes me sad that people would trade in a galaxy of culinary experiences for rib-eye, day in, day out.
There is also the question of sustainability. The simple truth is, for the sake of our over-populated planet, we all need to be aiming to eat less meat. The reasons are as obvious as they are urgent: the quantity of food produced by killing a fully-grown cow is far less than the quantity of food and water required to grow and nurture said cow. Some vegans have pounced on this and proclaimed that instead of fields of cows, we should be producing fields of soya instead, blithely ignoring that these can be just as catastrophic for the environment. The truth then, is that we probably need some animals and animal products to maintain the equilibrium mother earth needs. But it is equally true that most of us currently skew too far towards the meat side of the equation and that cutting back on meat is both prudent for our health,11 and kind to a world currently being ravaged by man-made climate change. To be frank, the world needs fewer, nor more, carnivores.
What are the downsides to the diet? Most carnivores describe a transient/semi-permanent diarrhea, probably related to the inability of pancreatic lipase to keep up with the sudden, massive volume of fat to absorb. In addition, the switch to ketosis, which can take a few weeks, is often described as being very unpleasant: sore throat, brain fog, decreased energy, irritability, vomiting, and a strange metallic taste in the mouth. Once in ketosis, some will have a permanently bad breath, related to the ketones. In addition, hyperglycemia has been described, probably related to the increased protein load. Unsurprisingly, and perhaps most worryingly, there is a general increase in low-density lipoprotein (LDL) cholesterol, which is strongly correlated with an increased cardiovascular risk. The carnivores tend to dismiss these claims by pointing out that they don’t think cholesterol causes heart attacks, missing out the robust data that links the two.12 The lack of long term information is also worrying, because we simply have no idea what effects the extreme diet will have many years down the line.
So why do so many feel so much better on it? That is hard to say, but probably represents a number of factors. First, the diet necessarily results in all sugar and ultra-processed foods being immediately discontinued. Most of us would automatically feel healthier eating less sugar and doughnuts. Secondly, both confirmation and selection biases play a role: people who start the diet want it to work, and will most likely overemphasize the positive effects, simultaneously downplaying the negative ones. And those who drop out are unlikely to be vocal about it on social media. Finally, it may indicate that certain medical conditions, such as non-coeliac gluten insensitivity and food allergies, are more common than medicine suspects. People who eliminate these from their diet will feel significantly better almost by default.
The carnivore diet, then, is an extreme diet with little historical or biological plausibility. It is very difficult for most people to maintain, is unkind to animals and disastrous for the planet. Its adherents, however, are passionate and convinced about its efficacy, and look disdainfully upon those who question it (they’re particularly vituperative about vegans who they believe are involved in a conspiracy to keep everyone sick). Nevertheless, there is very little beyond anecdote at this stage to point to its healthiness, and plenty of reasons to worry about what it may do in the long term. Quite frankly, I think it’s bizarre. Now if you’ll excuse me, I have a delicious, varied, healthy meal to start preparing which I hope to share with my friends. Can’t wait.
*Spoke too soon. Another orthopaedic surgeon who had his license temporarily suspended, Australian Dr Gary Fettke, does seem to think this.
[link url="http://science.sciencemag.org/content/345/6192/1236828"]1. Anton SC, Potts R, Aiello LC. Human evolution. Evolution of early Homo: an integrated biological perspective. Science (New York, NY). 2014;345(6192):1236828.[/link]
[link url="https://www.sciencedirect.com/science/article/pii/S0047248414000189"]2. Henry AG, Brooks AS, Piperno DR. Plant foods and the dietary ecology of Neanderthals and early modern humans. Journal of Human Evolution. 2014;69:44-54.[/link]
[link url="https://www.bmj.com/content/349/bmj.g4490"]3. Wang X, Ouyang Y, Liu J, et al. Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies. BMJ (Clinical research ed). 2014;349:g4490.[/link]
[link url="https://www.ncbi.nlm.nih.gov/pubmed/28338764"]4. Aune D, Giovannucci E, Boffetta P, et al. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality-a systematic review and dose-response meta-analysis of prospective studies. International Journal of Epidemiology. 2017;46(3):1029-1056.[/link]
[link url="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)32253-5/fulltext"]5. Miller V, Mente A, Dehghan M, et al. Fruit, vegetable, and legume intake, and cardiovascular disease and deaths in 18 countries (PURE): a prospective cohort study. Lancet (London, England). 2017;390(10107):2037-2049.[/link]
[link url="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(18)31809-9/fulltext"]6. Reynolds A, Mann J, Cummings J, Winter N, Mete E, Te Morenga L. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet (London, England). 2019;393(10170):434-445.[/link]
[link url="https://www.ncbi.nlm.nih.gov/pubmed/26021487"]7. Dietary fibre and incidence of type 2 diabetes in eight European countries: the EPIC-InterAct Study and a meta-analysis of prospective studies. Diabetologia. 2015;58(7):1394-1408.[/link]
[link url="https://www.ncbi.nlm.nih.gov/pubmed/18287346"]8. Weickert MO, Pfeiffer AF. Metabolic effects of dietary fiber consumption and prevention of diabetes. The Journal of Nutrition. 2008;138(3):439-442.[/link]
[link url="https://www.ncbi.nlm.nih.gov/pubmed/10916690"]9. Levin NA, Greer KE. Scurvy in an unrepentant carnivore. Cutis. 2000;66(1):39-44.[/link]
[link url="https://journals.lww.com/pec-online/Abstract/publishahead/Florid_Scurvy_in_an_Autistic_Child_on_a_Ketogenic.98294.aspx"]10. Ahmad SA, Al Thobiti TA, El Toum M, Al Harbi F. Florid Scurvy in an Autistic Child on a Ketogenic Diet. Pediatric Emergency Care. 2018.[/link]
[link url="https://www.ahajournals.org/doi/full/10.1161/CIR.0000000000000510"]11. Sacks FM, Lichtenstein AH, Wu JHY, et al. Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association. Circulation. 2017;136(3):e1-e23.[/link]
[link url="https://www.ncbi.nlm.nih.gov/pubmed/28444290"]12. Ference BA, Ginsberg HN, Graham I, et al. Low-density lipoproteins cause atherosclerotic cardiovascular disease. 1. Evidence from genetic, epidemiologic, and clinical studies. A consensus statement from the European Atherosclerosis Society Consensus Panel. European Heart Journal. 2017;38(32):2459-2472.[/link]
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