Is there any trial evidence for the carnivore diet?

No. There is no proper trial, no controlled feeding study, no hospital-unit data, no comparison group and no long-term follow-up. A review across four research databases found nine studies in people in total. It rated the evidence as very limited, because the studies were small, short and had no comparison groups.

But thousands of people say it fixed their health problems.

They do, and that is worth knowing rather than brushing off. What it cannot tell you is how big the effect is or how safe the diet is, for a built-in reason. The survey only took people who had stuck with it for six months, so everyone who quit because it went badly was left out before the first question. Side effect rates of 1 to 5 percent are rates among people it worked for.

Why do people feel better on it?

Several reasons fit the reports equally well, and nobody has pulled them apart. It is the most complete elimination diet possible, so anyone reacting to a certain plant food will improve. It is very high in protein, which curbs appetite and causes weight loss. And people who overhaul their diet also tend to change other habits and expect to feel better. Sorting this out needs a comparison group, which does not exist.

In the one group with measured rather than remembered results, typical LDL was 172 mg/dL. The survey's own authors called that markedly high. Triglycerides and HDL in those same people were good. No study has tracked what happens to people on this diet over time. So the honest answer is that the number is high and what it leads to is unknown.

Is it safe long term?

Nobody knows. The longest time on it recorded anywhere is a typical 14 months, self-reported, with no follow-up. On paper the diet falls short on vitamin C, thiamin, magnesium, calcium, folate and iodine, and 37 percent of people surveyed took no supplements at all. That mix is a reason to worry. It is not proof of harm.

Elimination1 study in people cited

Carnivore

Written by Aaron CuhaReviewed Sep 2026

Also called: All-meat diet, Zero carb, Lion diet

Nobody has ever run a proper trial of this diet. There is no controlled feeding study and no comparison group of any kind. Search PubMed for trials of an all-meat diet in people and you get vet studies in dogs.

What it actually is

Animal foods only. Meat, and in some versions fish, eggs and some dairy, with all plant foods cut out. The strictest version, sometimes called the lion diet, is beef or lamb, salt and water. In the largest survey of people on it, 85 percent ate red meat every day or more, and under 10 percent ate vegetables, fruit or grains more than once a month.

How its fans say it works

There are two arguments, and they should be kept apart. The first is elimination. Some plant foods contain compounds that cause problems in some people. Removing everything and adding nothing back is the bluntest, most complete elimination diet there is. That is real medical logic. The second argument is that animal foods give you everything you need and plant foods are not needed at all. That claim is bigger, and no study backs it.

What happened when calories were controlled

Best kind of study available: tracked, not tested

Nobody was given a diet. People who choose a diet differ from people who do not in other ways too, so this shows a link, not a cause.

None have been run. Not one controlled feeding study, not one hospital-unit study, not one study with a comparison group, not one trial of any kind. We say this flatly because it is the most important fact about this diet.

A 2026 review searched four big research databases and found nine studies in people in the whole literature. It rated the quality of evidence as very limited, because the studies were small, short and had no comparison groups. Its conclusion: staying on this diet long term cannot be recommended.
The research on people under this name is one survey, one paper that worked out nutrients on paper, some reviews, a study of social media posts and a letter criticising the survey. That is all of it.
With nothing to compare against, the size of any effect cannot be worked out. Not for weight, not for blood sugar, not for cholesterol, not for symptoms. A number with no comparison group describes what happened. It is not a result.

What happened when people just ate it

There is one survey, and the way it was built decides what it can tell you. Lennerz 2021 recruited 2,029 adults through social media who had eaten this way for six months or more. The typical person was 44 and had been on the diet 14 months, and 67 percent were men. 95 percent said their overall health improved, and 48 to 98 percent said various health problems got better. Reported side effects ran from under 1 to 5.5 percent. The typical BMI was reported as falling from 27.2 to 24.3. A smaller group shared lab results. Their HDL (good cholesterol) was 68 mg/dL and triglycerides 68 mg/dL, both good. But their LDL (bad cholesterol) was 172 mg/dL, which the authors themselves called markedly high. Now reread who could join: people still on the diet after six months or more. Anyone who tried it and quit, for any reason, including a bad reaction, was shut out by design. So the 1 to 5 percent side effect figures are rates among people it went well enough for to keep going. They are not the rate for everyone who tries. The survey was shared through carnivore community channels, so it reached the most committed fans. Everything except the lab results was self-reported. Starting points were recalled from memory, and there was no way to tell whether health changes came before or after the diet change. The one figure from real measured values is the LDL of 172, and it points toward harm.

Protein, and whether it muddies the result

Protein is high by design, and that probably does much of the work people credit to cutting out plants. Protein fills you up more than carbs or fat, and it protects muscle while you lose weight. So a diet that is almost all protein and fat will blunt appetite and cause weight loss for reasons that have nothing to do with skipping plants. Nobody has pulled those two apart. That would take a study with a high protein comparison group, and no such study exists.

The measured intakes behind the protein figures are on the protein page.

What reliably moves

Measure	Direction	From
LDL (bad) cholesterol	Up, and this is the one measured result	A typical 172 mg/dL in the survey takers who shared lab results. These are people who chose to share, inside a group that chose to join, and it is still the only figure here from real measurements rather than memory.
Triglycerides (blood fats) and HDL (good cholesterol)	Good	68 mg/dL and 68 mg/dL in that same group. In line with what cutting carbs does in general.
Fibre intake	Close to zero	A paper that modelled four made-up meal plans found fibre far below guidelines. It also found shortfalls in thiamin (vitamin B1), magnesium, calcium and vitamin C, and in iron, folate, iodine and potassium in some plans. Sodium was over its limit. This is worked out on paper, not measured in people.
Reported weight	Down	Survey takers recalled their BMI falling from 27.2 to 24.3. That is looking back from memory with no comparison group, so it cannot be read as the size of an effect.

Long term, and serious health events

Nothing. No follow-up of any kind, no long-term study, no registry, no data on what happened to people. The longest time on the diet recorded anywhere is a typical 14 months, self-reported, in a one-time survey. The 2026 review noted one case of health getting worse among the nine studies it found. Anyone who tells you this diet is safe long term, or dangerous long term, is telling you what they think rather than what has been measured. The honest answer is that the question is open. What the diet is made of gives real reasons to worry, mainly the measured LDL and the near-zero fibre, vitamin C, folate, magnesium and potassium.

Sources

Study in people2021
Behavioral characteristics and self-reported health status among 2029 adults consuming a carnivore diet
Current Developments in Nutrition
This was an online survey of adults who said they had eaten a carnivore diet for six months or more. 95 percent said their health got better, each problem was reported by 5.5 percent or fewer, and remembered BMI fell from 27.2 to 24.3. Among those who shared lab results, LDL (bad) cholesterol was 172, HDL 68 and triglycerides 68. There was no comparison group, and people who quit the diet were never asked.
Social media survey of adults self-identifying as carnivore for six months or more. Reported improved health in 95 percent, adverse symptoms under 1 to 5.5 percent, BMI recalled as falling 27.2 to 24.3. Among those reporting labs, LDL 172 mg/dL, HDL 68, triglycerides 68. No control group and total survivorship bias by design.
Review of studies2022
Limitations of self-reported health status and metabolic markers among adults consuming a carnivore diet
Current Developments in Nutrition
This is a formal critique of the carnivore survey above, printed in the same journal. There is no summary of it on PubMed, so we do not list its points. We note only that it exists.
A formal published critique of the survey above, in the same journal. No abstract is indexed, so its specific arguments are not reported here, only that the critique exists in the peer-reviewed record.
Review of studies2024
Assessing the nutrient composition of a carnivore diet: a case study model
Nutrients
No people were studied. Researchers built four sample carnivore meal plans on paper and checked them against Australian and New Zealand nutrient targets. The plans met targets for B vitamins, phosphorus, zinc, selenium and vitamin A, and went over on salt. They fell short on thiamin, magnesium, calcium and vitamin C, and far short on fibre.
Four hypothetical meal plans modelled against Australian and New Zealand reference values. Met thresholds for B vitamins, phosphorus, zinc, selenium and vitamin A; exceeded sodium; fell short on thiamin, magnesium, calcium and vitamin C, with fibre significantly below recommendations. Modelling, not measurement in people.

What people report

These are things people say about their own eating. Nobody checked them, so they are not evidence. They are here because they tell you what to expect and what to watch for, which the studies do not. They cannot tell you whether anything works.

Fast relief from autoimmune, gut and skin problems is the most common reason people give for starting, and the most common benefit they report. That is exactly what a hard elimination diet would do for someone reacting to a food. It is also what expecting to feel better, and symptoms easing on their own, would produce.
Strong appetite loss and weight loss without trying.
Diarrhoea in the first weeks, talked about a lot and usually blamed on the amount of fat.
Going days without a bowel movement, called normal in the community and not studied anywhere.
A sizeable minority report a big LDL rise when they retest.
Losing power for hard, fast exercise.
Feeling cut off socially and trouble eating away from home, the most common reason people give for stopping.

Sources: The Lennerz 2021 survey of 2,029 people who called themselves carnivore, r/carnivore and r/zerocarb, and write-ups from doctors who promote the diet. The same journal published a formal critique of the survey's weak points. It is all unchecked self-report, and only from people who stuck with it. For this diet it is nearly the whole evidence base, not an add-on to it.

Who this is wrong for

Anyone with an inherited cholesterol disorder or existing heart disease. The one set of measured cholesterol results shows LDL well above normal limits, and there is no data on outcomes either way.
Anyone with chronic kidney disease. The protein load is a medical question that needs a kidney doctor.
Anyone with a history of gout or high uric acid.
Anyone pregnant or breastfeeding, and any child. There is no safety data for these groups, and the nutrient gaps found on paper matter most when needs are highest.
Anyone who will not take supplements or get tested. In the survey, 37 percent took no vitamins at all, on a diet that on paper falls short on vitamin C, thiamin, magnesium, calcium, folate and iodine.
Anyone with a history of eating disorders. This is the strictest diet on this site.

Questions

Is there any trial evidence for the carnivore diet?: No. There is no proper trial, no controlled feeding study, no hospital-unit data, no comparison group and no long-term follow-up. A review across four research databases found nine studies in people in total. It rated the evidence as very limited, because the studies were small, short and had no comparison groups.
But thousands of people say it fixed their health problems.: They do, and that is worth knowing rather than brushing off. What it cannot tell you is how big the effect is or how safe the diet is, for a built-in reason. The survey only took people who had stuck with it for six months, so everyone who quit because it went badly was left out before the first question. Side effect rates of 1 to 5 percent are rates among people it worked for.
Why do people feel better on it?: Several reasons fit the reports equally well, and nobody has pulled them apart. It is the most complete elimination diet possible, so anyone reacting to a certain plant food will improve. It is very high in protein, which curbs appetite and causes weight loss. And people who overhaul their diet also tend to change other habits and expect to feel better. Sorting this out needs a comparison group, which does not exist.
What about the LDL?: In the one group with measured rather than remembered results, typical LDL was 172 mg/dL. The survey's own authors called that markedly high. Triglycerides and HDL in those same people were good. No study has tracked what happens to people on this diet over time. So the honest answer is that the number is high and what it leads to is unknown.
Is it safe long term?: Nobody knows. The longest time on it recorded anywhere is a typical 14 months, self-reported, with no follow-up. On paper the diet falls short on vitamin C, thiamin, magnesium, calcium, folate and iodine, and 37 percent of people surveyed took no supplements at all. That mix is a reason to worry. It is not proof of harm.