Imagine doing your entire food shop at a butcher's. No vegetables, no bread, no fruit, no pasta, mil or biscuits – just a trolley full of meat, fish, eggs and lard.
That’s the carnivore diet. Its gospel has been preached all over the internet – by fitness influencer Brian Johnson (aka Liver King), Canadian psychologist Jordan Peterson and podcaster Joe Rogan (who said the diet gave him “sporadic bouts of hellacious projectile doodoo”).
But despite such vivid imagery, the carnivore cult is growing.
Data from Google Trends shows that searches for the term “carnivore diet” roughly tripled in the UK and US from 2022 to 2025, and there are now more than 160 carnivore cookbooks listed for sale on Amazon.
There’s no real science proving the diet is beneficial, but many meat munchers feel confident in their choice because they think our hunter-gatherer ancestors ate mainly (or only) animals.
The carnivore diet, they say, is a better fit for our biology than a modern diet of carbohydrates, processed foods and farmed plants. It’s what we evolved to eat.
But here’s the thing: there’s a limit to what The Flintstones can teach us about nutrition.
What people imagine to be ‘ancestral’ eating is not only inaccurate, but often unhealthy. And any lessons we can learn from our Stone Age predecessors are nothing like what the podcast bros would have you believe.
'Man the hunter'
The first thing to note is that our ancestors weren’t actually carnivores. That’s a misplaced narrative based on outdated archaeology.
Dr Emma Pomeroy is an Associate Professor in the Evolution of Health, Diet and Disease at the University of Cambridge. She says: “We have this idea of cavemen – and it usually is men – eating a very high meat diet and not relying on anything else. For most humans, that wasn’t the case.”
Why, then, do so many of us think it was?
Well, animal bones and stone tools can survive for ages, so archaeologists have long had clear evidence that early humans hunted, butchered and ate animals. Plant matter, on the other hand, decomposes quickly.
So, the archaeological record has traditionally been “biased towards the hunting record,” as a result, explains Prof Dorian Fuller, an archaeobotanist at University College London.
We know better now. Archaeologists have amassed a wealth of evidence that our ancestors ate plants. Some of the strongest comes from isotope analysis. Isotopes are distinct versions of chemicals that can give us clues about what humans ingested during their lives.
“You can analyse bones and tooth enamel for isotopes,” says Fuller. “All the isotopes in humans come from what we ate and there are different variants.”
For example, nitrogen gets heavier every time it’s eaten. It’s light in plants, heavier in herbivores, heavier still in carnivores – so the atomic weight of the nitrogen in an animal’s remains (human or otherwise) can give archaeologists an indication about where that animal’s diet fell on the food chain.
Similarly, different plants have different carbon isotopes. So, depending on the types of carbon found in a skeleton, archaeologists can guess the type of plants that a person ate.
“If you combine that with the nitrogen isotopes, you can guess, ‘This looks like a diet that’s high in fish and nuts,’” says Fuller. “Or, ‘This looks like it’s high in meat and millet.’”
This is how a 2024 study was able to conclude that Stone Age hunter-gatherers in Taforalt, Morocco, were mainly eating plants up to 15,000 years ago.
Scientists at the Max Planck Institute for Evolutionary Anthropology, in Germany, analysed the isotopes of zinc, strontium, carbon, nitrogen and sulphur from dental enamel, bone collagen and plant remains.
Doing so revealed that this Palaeolithic group were more gatherers than hunters, relying on plant foods such as acorns, oats and pistachios for survival.
Archaeologists can also analyse the gunk that builds up on unbrushed teeth, which Pomeroy describes as “a really amazing source of information on what people were eating.” As that gunk forms, it traps particles of food and plant fragments.
Archaeologists can analyse DNA from those tiny pieces to find out exactly what a person ate.
Then there’s ethnographic evidence – studies on modern hunter-gatherer populations. A 2023 study found that, out of 63 foraging societies studied in the last 100 years, there was clear evidence that women hunted in 50 of them (79 per cent).
And we also know that modern hunter-gatherers usually eat a lot of plants.
The Tsimané of the Amazon get a lot of their calories from plantains and manioc, for instance, while Australian Aboriginals eat plenty of nut grass and water chestnuts.
For Pomeroy, this makes sense. “Plant foods are much more reliable than meat,” she says.
“Yes, hunters might bring back a large amount of meat in one go. But on days when they don’t, people still have to eat. So, that reliable aspect of the diet, in many populations, would have been the plant foods.”
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Adapt or die
Palaeolithic people ate plants; the evidence for that is clear. But that doesn’t mean all Palaeolithic people ate the same things – that there was a single, homogenous Palaeolithic diet.
Palaeolithic humans lived across vastly different environments, from forests and deserts, to savannas and mountains.
In fact, a 2018 paper argued that part of the reason why Homo sapiens outlived previous hominins was our ability to live in a wide variety of challenging landscapes – something it called the ‘generalist specialist’ niche.
In Sri Lanka, says Fuller, we have evidence that hunter-gatherers foraged for most of their diet, eating plenty of nuts and wild fruits, while also learning to shoot small monkeys and birds in the forest.
Whereas, in the Arctic Circle, the traditional diet of Inuit populations has long consisted of whale and seal blubber without many plants, because that’s what is available there.
Even if there was one ‘genuine’ Palaeolithic diet, you couldn’t follow it now even if you wanted to, because the foods they ate simply don’t exist anymore – certainly not on supermarket shelves.
For example, the wild melons gathered by our ancestors were bitter and sour, whereas ours have been made sweet by centuries of selecting the tastiest fruit to farm. Similarly, their grains would have been smaller, less starchy and more fibrous than ours.
Their peaches were cherry-sized, their bananas were full of pips and their carrots were thin and white or purple.
Agriculture changed all that. Over millennia, farmers have chosen plants that they like to grow and eat, and our food has morphed as a result. Generally, it has become sweeter, starchier and less fibrous.
“We’ve selected cereals that have slightly more carbohydrate than their wild ancestors and mutated forms of fruit that are high in sugar,” says Fuller. “If you wanted to take those out of your diet, you’d have to try to find non-sweet versions of these things, which would be very hard to do.”
It’s much the same story when it comes to meat, adds Pomeroy. We’ve bred our livestock to be larger, so they produce more meat per animal. But also, hunter-gatherers would have eaten their prey from nose to tail, not just selected a few choice cuts.
“It’s very rare that people who claim to be eating these diets are eating the brain, the lungs, the eyes, the tongue, all the internal organs, the bone marrow,” says Pomeroy. “But people used the whole thing.
It’s hard work hunting and you’re not just going to say, ‘I’ll have a nice bit of rump steak.’”
Different diets, different bodies
Not only is our food different to that of our ancestors, but so are we. Our bodies have adapted to cope with our agricultural diets and Pomeroy says it’s “problematic” to suggest otherwise.
“We know that human populations have evolved to eat some of the products of agriculture,” she says. “A classic example is lactase persistence. Mammals stop consuming milk once we’ve been weaned, so we don’t need lactase – the enzyme that breaks down the sugars in milk.”
Yet, populations that relied on cattle and dairy products for survival have developed lactase persistence, so they can digest dairy throughout adulthood.
Another example is amylase enzymes, which break down starches for digestion. Modern humans have more amylase enzymes than other primates, including gorillas, chimpanzees and our hominin predecessors such as Neanderthals.
“But, within modern humans, there’s a huge amount of variation,” says Fuller. “Some populations have three or four copies [of the amylase gene], some populations have 12.”
So, some human groups now have genetics that are better suited to higher starch diets, indicating that they may have been historically reliant on sources of carbohydrate – such as grains, cereals and tubers – for survival.
That’s the case in temperate environments, far away from the poles and equator, such as Britain and much of North America.
Meanwhile, Inuit people who live in the Greenland Arctic have undergone genetic adaptations to cope with their meat-based diets, says Pomeroy.
“Their metabolism has adapted to enable them to eat that high-fat diet without the metabolic risk that we would see if most people in other countries were to eat that kind of diet.”
All over the world, we’ve evolved and adapted to our environments, just as our Palaeolithic ancestors did. So, attempting to revert to our Stone Age diets might not be best for our biology.
But, for argument’s sake, let’s assume that you could pick a Palaeolithic diet suited to your biology, that you could find Stone Age crops and that your body wouldn’t reject your new menu. You would still be living in an agricultural society.
Unless you’re hunting and foraging all day in Stone Age landscapes, you wouldn’t be living the lifestyle of a Palaeolithic person. You wouldn’t be surviving off what you could find – and that’s probably a good thing.
Visions of the Palaeolithic past tend to romanticise it as the nutritional and evolutionary ideal, but it could be precarious.
The advent of agriculture enabled humans to live longer, grow in population and enjoy more reliable access to food. As Pomeroy says, “I don’t think anyone would want to move away from the food security that we have in rich countries today.”
In other words, just because something might be ‘what our ancestors did,’ it doesn’t mean it’s what they wanted to do. They probably would have liked reliable access to food, thank you very much.
More variation
Perhaps, the most annoying thing about fans of the carnivore diet, however, is that they do have a point.
Even though we’re living longer and there are more of us compared to Stone Age times, Pomeroy says that skeletons from agricultural societies seem to have more signs of chronic disease, such as diabetes and heart disease.
And, in the last few centuries, what we eat has changed a lot.
“The nugget of truth here is the food system has rapidly changed over the last couple of hundred years and our biology hasn’t to that extent,” says Dr Emily Leeming, a dietitian and scientist at King’s College London.
But, while Paleo and carnivore fans may have spotted this problem, they’ve got the solution all wrong.
Leeming says the ‘ancestor diet’ trope is often attached to diets that “end up being incredibly restrictive,” centred on demonising and cutting out entire food groups. But Pomeroy, Fuller and Leeming all agree that what we need is more variation, not restriction.
“The real problem with an agricultural diet, if we can call it that, is the reduction in the diversity of plant foods,” says Fuller. He explains that we rely too heavily on carb-rich foods such as wheat, rice and corn, while missing out on a wide range of fruits, vegetables, nuts, seeds and legumes.
“We’ve become quite narrow in the plants that we eat,” agrees Pomeroy. She adds that we process foods more than we did in hunter-gatherer times. We would have eaten whole fruits and whole grains with their fibre intact.
“We think the ancestral diet was incredibly diverse, really high in fibre, with lots of different plant foods and fibre types,” says Leeming, adding that our gut health would have benefited from a “wealth of different types of microbes, far more than we have in our diets now.”
Also, says Leeming, a key source of fibre is whole grains.
Paleo and carnivore diets restrict or eliminate this food group because it’s a source of carbohydrate, aka sugar, something proponents of these diets say Palaeolithic people didn’t eat. But we know that our ancestors were eating grains.
Those of us in the modern western world, in contrast, are “seriously lacking whole grains”, says Leeming.
“This has real consequences, not just for your gut microbiome, but the health of your entire gut – things like bowel cancer – and also heart health and metabolic health, including type 2 diabetes.”
Fuller adds we have evidence, too, that Palaeolithic people were eating more nuts and seeds than we do today, and benefitting from healthy fats such as omega-3, good for longevity and the brain.
Eating for survival
All in all, everything that we assume about Stone Age diets is wrong. Our ancestors didn’t just eat meat, they ate different things depending on where they lived and, usually, plenty of plants.
That’s because Palaeolithic people weren’t eating to get ‘ripped’, chase podcast stardom or start arguments on social media. Their diets were all about survival.
To survive, they adapted to their environments. And, if we want to continue to survive, we need to adapt how we eat too. For Fuller, Pomeroy and Leeming, that means eating with the climate in mind.
Leeming says that if we’re to stick around, our diets should consider both nutrition and sustainability. This means prioritising vegetables and fruits, followed by wholegrains and plant-based protein sources, with minimal meat and dairy products.
Because, in the end, it doesn’t really matter what our ancestors ate. We live in different environments, with different foods, facing a different set of challenges.
Our ancestors did what they could to survive. Now it’s our turn.
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