Carnivore or vegan: what does the evidence say?

The objection

“People on carnivore say they’ve lost weight, their bloating has gone and their blood sugar has come down, and plenty of them tried going vegan first. Humans have always eaten meat. The vegan studies are questionnaires filled in by health-conscious people, and the cholesterol scare is decades old. If you’re going to cut out a food group, why not cut out the plants?”

The answer

The two diets are nowhere near level on evidence. Vegetarian and vegan diets have been followed in cohort studies of hundreds of thousands of people and tested in 30 randomised trials pooled in a 2023 meta-analysis [4][5], while a 2026 scoping review of the carnivore diet found nine studies in people, most of them small, and concluded that its long-term safety cannot yet be reliably assessed (Lietz et al., 2026) [1].

The objection gets some things right. People on the diet do report feeling better: in the largest survey of them, 2,029 adults who had eaten it for a median of 14 months reported few side effects and high satisfaction, and by their own account their median BMI had fallen from 27.2 to 24.3 (Lennerz et al., 2021) [2]. Most of the evidence on vegans is observational, and Is a vegan diet healthy? sets out where it falls short, including EPIC-Oxford’s findings that vegetarians had more strokes and vegans broke more hips [29][27]. Vegans also need vitamin B12, which plants don’t provide, and the British Dietetic Association says their only reliable sources are fortified foods and supplements [28]. The case against carnivore rests on measurements as well as theory, though: modelled carnivore meal plans supply almost no fibre and fall short of several vitamins and minerals, and in the people who have been tested the diet has tended to push LDL cholesterol up [1].

Is there any long-term evidence on the carnivore diet?

There is no long-term evidence on the carnivore diet, and the short-term evidence is thin. The 2026 review searched four databases and found nine studies published between 2021 and 2025: five small case-based studies, two surveys recruited through social media, one exploratory study and one modelling study [1]. The reviewers rated the level of evidence mostly low, pointed to small samples, the absence of control groups and short study durations, and concluded that long-term adherence to the diet cannot be recommended [1].

The 2021 survey is the biggest of the nine. Its respondents had been on the diet for a median of 14 months, 93% had started it for their health, 85% ate red meat daily or more often, and fewer than 10% ate vegetables, fruit or grains more often than once a month [2]. The 262 respondents with diabetes reported falls in their HbA1c, a measure of long-term blood sugar, and in their use of diabetes medicines [2]. The authors were frank about the limits. Nothing was measured by the researchers, everything was self-reported and open to recall bias, people who began the diet when they felt at their worst might credit it with a natural recovery, and anyone who felt worse on it had probably given up before the survey reached them [2]. Four researchers replying in the same journal in 2022 added that the blood test results could not be verified, and argued that the 28 duplicate responses the survey’s authors had found by email address and deleted showed a risk that some people had answered more than once using other addresses (Kirwan et al., 2022) [2][3].

Plant-based eating has a far larger record, though most of it is observational too. A 2023 meta-analysis of 13 cohort studies with 844,175 participants found 21% less ischaemic heart disease in vegetarians than in non-vegetarians (relative risk 0.79, 95% CI 0.71 to 0.88), a link its authors judged probably causal; for vegans the estimate was 0.82 (0.68 to 1.00), and the studies’ risk of bias was rated moderate to serious (Dybvik et al., 2023) [4]. For stroke the same analysis found no clear link either way in vegetarians (0.90, 0.77 to 1.05) [4], while EPIC-Oxford, a British cohort, found a 20% higher rate of stroke in vegetarians, vegans among them, than in meat-eaters (hazard ratio 1.20, 1.02 to 1.40), about three more strokes per 1,000 people over ten years, mostly because of more haemorrhagic strokes, the kind caused by bleeding (Tong et al., 2019) [29].

What does a carnivore diet do to cholesterol?

In the studies that have measured it, a carnivore diet has mostly raised LDL cholesterol, which causes heart disease, and trials of low-carb diets suggest the rise is biggest in lean people. Among respondents to the 2021 survey who gave their results, median LDL was 172 mg/dL (about 4.4 mmol/L) on the diet against 126 mg/dL (about 3.3 mmol/L) before it, while HDL cholesterol and triglycerides were, in the authors’ words, optimal [2]. Of respondents who reported a blood lipid problem, 56% said it had resolved or improved and 27% said it was new or had got worse [2]. In a 2025 study of 24 German carnivore dieters who supplied blood tests from before and during the diet, median LDL rose from 157 to 256 mg/dL (about 4.1 to 6.6 mmol/L), a rise the authors, one of whom follows an animal-based diet and works with a supplier of supplements for carnivore dieters, called striking (Klement and Matzat, 2025) [6]. Most of the participants’ other blood values stayed within reference ranges on the diet, and the two who had started with pre-diabetic HbA1c and the six with high triglycerides all saw them fall [6].

Trials of low-carbohydrate diets help explain who is most affected. A 2024 meta-analysis of 41 trials with 1,379 people eating under 130 g of carbohydrate a day found that LDL rose by 41 mg/dL, about 1.1 mmol/L (19.6 to 63.3 mg/dL), in trials whose participants averaged a BMI under 25, did not change at a BMI of 25 to 35, and fell by 7 mg/dL (about 0.2 mmol/L) at 35 or more (Soto-Mota et al., 2024) [7]. Across 27 trials of ketogenic diets with 1,278 people, LDL was 0.35 mmol/L higher (0.20 to 0.50) after the ketogenic diets, while triglycerides fell and HDL rose, and the authors urged caution (Wang et al., 2024) [8]. Plant-based diets push the other way: a 2023 meta-analysis of 30 randomised trials found that vegetarian and vegan diets lowered LDL by 0.30 mmol/L (0.19 to 0.40) compared with omnivorous diets, with similar effects across ages, continents, study lengths and states of health (Koch et al., 2023) [5]. Does a vegan diet lower cholesterol, and what about statins? sets that beside what a statin does.

Those rises matter because the evidence on LDL is unusually strong. In 2017 the European Atherosclerosis Society’s consensus panel weighed genetic studies and meta-analyses of more than 200 cohort studies, Mendelian randomisation studies and randomised trials, with more than 2 million participants between them, and concluded that the evidence unequivocally establishes that LDL causes atherosclerotic cardiovascular disease, with risk rising in step with the level of LDL and, it appears, with how long the arteries are exposed to it (Ference et al., 2017) [9]. In statin trials, each 1 mmol/L reduction in LDL cut the yearly rate of heart attacks, ischaemic strokes and procedures to restore blood flow through blocked arteries by just over a fifth (Cholesterol Treatment Trialists’ Collaboration, 2010) [10].

Some low-carb researchers suggest the rise may matter less in lean, metabolically healthy people, and the 2021 survey’s authors raised the possibility that high LDL alongside low triglycerides reflects a lower-risk kind of particle, while saying it was unclear whether the diet’s other benefits would outweigh it [2]. In a 2022 analysis of a web survey of 548 people on carbohydrate-restricted diets, 100 fitted a pattern the authors called the lean mass hyper-responder, with very high LDL alongside high HDL and low triglycerides, and the biggest LDL rises tended to come in people at otherwise low cardiometabolic risk (Norwitz et al., 2022) [11]. Whether that makes the LDL safe has not been shown. The KETO-CTA study, set up to test it, scanned the coronary arteries of 100 people whose LDL had risen to 190 mg/dL or more on a ketogenic diet and reported in 2025 that neither LDL nor ApoB predicted how their plaque changed over a year [12]. In 2026 the journal retracted that paper at the request of the authors and editors, after concerns about its methodology that affected the reliability of the data [13]. If your LDL has gone up on any diet, talk to your GP about what it means for you, and don’t stop a statin or any other medicine without their advice.

Why do some people feel better on a carnivore diet?

Some people do feel better on a carnivore diet, at least at first, and the 2026 review judged that these effects are likely driven by people’s own perceptions, placebo responses and the metabolic changes of ketosis, and have not been validated by robust research [1]. Expectation alone can do a good deal: the reviewers point to studies in which believing a supplement worked improved mood or cognitive performance even when the supplement was inert [1].

People with irritable bowel syndrome (IBS) may have a more specific reason to feel better. In the 2021 survey, 59% of the 531 respondents with a gastrointestinal condition said it had resolved on the diet and 38% that it had improved [2]. The NHS’s advice for easing bloating, cramps and wind in IBS is to eat oats regularly and up to a tablespoon of linseeds a day, and to avoid foods that are hard to digest, such as cabbage, broccoli, cauliflower, Brussels sprouts, beans and onions, and products containing the sweetener sorbitol [14]. A diet of meat leaves out every food on that list to avoid, along with the oats and linseeds. The tested way to do something similar is the low FODMAP diet, which the British Dietetic Association describes as restricted in fermentable carbohydrates, and for which people can be referred to an NHS dietitian for support [15]. In a 2022 network meta-analysis of 13 randomised trials with 944 patients, it ranked first of the approaches compared for overall IBS symptoms, pain and bloating, cutting the risk that symptoms failed to improve by a third against people’s usual diet (relative risk 0.67, 0.48 to 0.91), though most of the trials did not study the reintroduction of foods afterwards (Black et al., 2022) [16]. The NHS says to see a GP if you need to avoid lots of different foods to control IBS, and for constipation its advice is to eat more soluble fibre, from oats, pulses, carrots, peeled potatoes and linseeds [14].

The 2026 review also describes a 2024 case series in which seven people with inflammatory bowel disease went into clinical remission on a ketogenic carnivore diet, some of them cutting or stopping medicines [1]. A case series has no comparison group, so it can’t show what caused the remission.

Does losing weight on a carnivore diet prove it works?

Losing weight on a carnivore diet doesn’t show that cutting carbohydrate has any special effect, and the most tightly controlled studies find that it brings no extra fat loss when calories are matched. A 2017 meta-analysis of 32 controlled feeding studies that swapped carbohydrate for fat while keeping calories the same found energy expenditure 26 kcal a day higher and fat loss 16 g a day greater on the lower-fat diets (Hall and Guo, 2017) [17]. When 17 men with overweight or obesity living on metabolic wards moved from a high-carbohydrate diet to a ketogenic one with the same calories, their body fat loss slowed, while their bodies used more protein and they lost fat-free mass (Hall et al., 2016) [18].

The idea that cutting carbohydrate makes people eat less was tested directly in 2021 at the US National Institutes of Health. Twenty adults living on a hospital ward ate as much as they liked of a minimally processed, plant-based, low-fat diet for two weeks and a minimally processed, animal-based ketogenic diet for two weeks, in random order. On the plant-based diet they ate 689 kcal a day less over the two weeks, and 544 kcal a day less in the final week, which the authors concluded was inconsistent with the theory that carbohydrate drives overeating; one participant dropped out because of low blood sugar on the ketogenic diet (Hall et al., 2021) [19]. Two weeks on each diet says little about the long term. Ketogenic diets do bring weight loss in trials: weight was 2.59 kg lower on average (1.28 to 3.90) after them in Wang and colleagues’ 2024 meta-analysis [8]. They can also be built from plants, as the answer on vegan keto and low-carb explains.

Do carnivores or vegans live longer?

Nobody knows how long people on a carnivore diet live, because none of the studies of the diet has followed people long enough to find out [1]. The nearest evidence comes from cohort studies of people eating less carbohydrate, split by whether the fat and protein that replaced it came from animals or plants, which the chart above shows. In a 2018 pooled analysis of four cohorts with 154,344 people and 30,959 deaths, eating patterns that swapped carbohydrate for animal fat and protein, from foods such as lamb, beef, pork and chicken, were linked to an 18% higher death rate (hazard ratio 1.18, 1.08 to 1.29), and those that swapped it for plant fat and protein to an 18% lower one (0.82, 0.78 to 0.87) (Seidelmann et al., 2018) [20]. Even the fifth of its US cohort eating the least carbohydrate got a median 37% of their calories from it, a long way from a carnivore diet [20].

A 2023 meta-analysis of ten cohort studies with 421,022 people found the plant-based pattern linked to a 13% lower risk of death (0.87, 0.78 to 0.97), while the animal-based pattern’s 1.08 (0.97 to 1.21) was not statistically significant, though it was linked to more deaths from cancer (1.16, 1.02 to 1.31), and neither pattern was linked to deaths from cardiovascular disease; the authors rated their evidence low in certainty (Ghorbani et al., 2023) [21]. The largest review, of 18 cohorts with 779,158 people (Duc and Nguyen Di, 2026), found neither pattern clearly linked to death rates in the general population: 0.93 (0.85 to 1.01) for low-carb eating high in plant protein and unsaturated fat, and 1.04 (0.95 to 1.15) for the kind high in animal protein and saturated fat [22]. Among people who already had a chronic disease, the plant-leaning pattern went with a 28% lower death rate (0.72, 0.69 to 0.76), evidence the authors rated high in certainty, while the animal-leaning pattern was again not linked to death rates (1.05, 0.95 to 1.15) [22].

What the carnivore diet removes has a longer record. A 2019 series of meta-analyses covering 185 prospective studies and 58 trials found that the people who ate the most fibre had 15 to 30% lower death rates from all causes and from cardiovascular disease, and less heart disease, stroke, type 2 diabetes and bowel cancer, than those who ate the least, with the largest risk reductions at 25 to 29 g a day and dose-response curves suggesting more could do even better, evidence the authors graded moderate in certainty (Reynolds et al., 2019) [23]. Carnivore meal plans modelled in two of the studies in the 2026 review supplied under 1 g of fibre a day, along with less vitamin C, magnesium, calcium and thiamine than reference intakes and far more vitamin A than recommended [1]. The diet is also built on red meat, which 85% of the 2021 survey’s respondents ate at least daily [2]. In 2015 the World Health Organization’s cancer agency, IARC, classified red meat as probably carcinogenic to humans, mainly for bowel cancer, while noting that red meat has nutritional value [24]; Does red and processed meat cause cancer? goes through that evidence.

For vegans the evidence on lifespan is mixed. In the Adventist Health Study-2, which followed 73,308 North American Adventists for almost six years on average, vegetarians as a whole had a 12% lower death rate than non-vegetarians (hazard ratio 0.88, 0.80 to 0.97), and the vegans’ 0.85 had a range (0.73 to 1.01) that could not rule out no difference (Orlich et al., 2013) [25]. A pooled analysis of two British cohorts with 60,310 people found no difference in death rates between vegetarians, vegans among them, and comparable regular meat-eaters (1.02, 0.94 to 1.10) (Appleby et al., 2016) [26]. Vegans in EPIC-Oxford had 2.3 times the meat-eaters’ rate of hip fracture after allowing for BMI and lifestyle (hazard ratio 2.31, 1.66 to 3.22), about 15 more hip fractures per 1,000 people over ten years (Tong et al., 2020) [27]. A 2026 meta-analysis of four cohort studies with 529,672 people found the same pattern, with vegans’ risk of hip fracture 75% higher than meat-eaters’ (1.75, 1.17 to 2.63), evidence it rated very low in certainty (Ballarin et al., 2026) [30].

If you take insulin or other diabetes medicines, blood pressure tablets or a statin, speak to your GP before making a big change to how you eat, and don’t stop or change any medicine without their advice. In the 2021 survey, 84% of the 82 respondents who had taken diabetes tablets said they had stopped them on the diet [2], which is something to do only on a doctor’s advice. The carnivore diet largely cuts out carbohydrate and, depending on how much protein people eat, can be ketogenic [1]. Diabetes UK warns that cutting carbohydrate while taking insulin or another diabetes medicine that can cause hypos raises the risk of a hypo, and that people with type 2 diabetes taking an SGLT2 inhibitor such as dapagliflozin should speak to their healthcare team first and may need to stop it, because these drugs can raise the risk of diabetic ketoacidosis when carbohydrate is cut [31]. Dapagliflozin is also prescribed for heart failure and chronic kidney disease, and the NHS lists diabetic ketoacidosis among its serious side effects [32]. A 2026 review of the risks of ketogenic diets lists familial hypercholesterolaemia, an inherited form of high cholesterol, and advanced liver or kidney disease among the conditions the diet may make worse (Dyńka et al., 2026) [33]. Cutting out whole food groups can also become a way of restricting how much you eat. If that is happening, a GP or an eating-disorder charity can help: Beat in the UK, Bodywhys in Ireland, ANAD in the US, NEDIC in Canada, the Butterfly Foundation in Australia, and EDANZ, which supports families and carers, in New Zealand.