The Surprising Science of the All-Meat Diet

Dr. Nicholas Norwitz, M.D. Ph.D. writes a best-selling science newsletter, StayCurious Metabolism, where he strives to empower readers with deep knowledge of cutting-edge health science.

The more I heard about the carnivore diet, the more interested I became.

I‘ll admit, I started as a skeptic. Everything I’d been taught throughout my life and medical training suggested this simply couldn’t make sense. No plant material whatsoever? Just meat, eggs, and fish? No fiber? What about polyphenols? Vitamin C?

It seemed radical.

Yet, equally radical were the stories of recovery I kept hearing from people with inflammatory bowel disease, mental health disorders, and even severe autoimmune conditions.

For example, one woman told me:

“After 20 years of juvenile rheumatoid arthritis that caused two joints to be replaced as a teenager, in a desperate attempt to heal, I tried an elimination diet of only meat and salt, which put my disease into full remission. It got me off of eight medications and put my major depressive disorder and chronic fatigue into remission as well. More research is desperately needed.”

That woman, Mikhaila Peterson (now Mikhaila Fuller), has gone from being a suffering, desperate patient to a powerful businesswoman and proud new mother with a full life.

Mikhaila Fuller and her newborn. (Courtesy of Mikhaila Fuller) — Mikhaila Fuller and her newborn. Courtesy of Mikhaila Fuller

So, as a medical doctor with a doctoral degree, I’m left with a simple conclusion that doesn’t take a doctorate to figure out: While skepticism is where evidence is lacking, so is curiosity. How could any self-respecting doctor fail to be curious about a diet that can bring people back to life when the best conventional treatments have failed to do so?

Let’s ask: Is the carnivore diet metabolic salvation or a dangerous fad? Or is it something else?

Let’s interrogate science and see where it stands.

What the Carnivore Diet Does to Your Gut

Does lack of fiber on an all-meat diet stop you from having a bowel movement?

Actually, no. In fact, when I tried it myself, I was surprised to find how regular my bowel movements were. If anything, they improved. Now, that’s not everyone’s experience. However, it does line up with some of the clinical literature.

In some patients with constipation, fiber elimination appears to improve bowel movements. For example, a 2012 study published in the World Journal of Gastroenterology had people with chronic constipation simply reduce or eliminate fiber.

Those who eliminated fiber had their bowel frequency improve from one movement every 3.75 days to one every day, and bloating and straining also completely resolved.

There was even a dose relationship: The more fiber people ate, the worse their symptoms became.

But it goes deeper than regularity.

What if a carnivore diet could be used to treat severe cases of inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease?

Several years ago, my colleague, Dr. Soto Mota, a clinical researcher and internal medicine consultant at the National Institute of Medical Sciences and Nutrition Salvador Zubirán in Mexico City, and I published a case series of ten patients who used a carnivore diet for exactly that purpose. These were severe, treatment-resistant cases. Many had already failed long lists of medications, and some had undergone surgeries to remove portions of their intestines. Yet each patient reported substantial improvements on a carnivore diet.

Interviewing them was remarkable, hearing their stories in their own words and then codifying those experiences. One patient described the transformation this way:

“[A] carnivore diet let me forget that I have Crohn’s. No drugs, no surgery … The decades that I dealt with Crohn’s are like another lifetime.”

But if the carnivore diet really can work as a treatment for inflammatory bowel disease, what are the plausible mechanisms?

First, when you remove carbohydrates from your diet, your body converts fat into molecules called ketones. Ketones aren’t only fuel; they also act as signaling molecules, nudging certain immune cells toward an anti-inflammatory state.

Second, the microbiome changes. A study published in the journal Cell Host & Microbe found that fiber-free diets alter microbiome patterns linked to colitis. In fact, fiber-free diets are already used for treatment-resistant IBD, with reported response rates of 60 to 85 percent. Most people, including many physicians, have never heard of using fiber-free diets for IBD, partly because those diets are usually delivered as unpalatable liquid formulas. Few have asked whether you could reach the same endpoint by simply eating meat.

Does carnivore stop you from having a bowel movement? No.

Does it destroy microbiome diversity? No. It certainly changes the structure of the microbiome, and the long-term consequences of that are unknown. Could it negatively affect longevity? Potentially. These are sincere, open questions.

Does it have therapeutic potential for some people with compromised guts? Emerging evidence says yes.

Now, it’s important to be clear and distinguish an intervention used as a medical therapy from some broadly applicable health hack. None of the above is meant to suggest that a carnivore diet is optimal for already healthy people, promotes longevity, or optimizes microbiome health in the average person.

The more modest claim is that, for certain patients who are suffering—whether from severe constipation or treatment-resistant IBD—there’s real therapeutic promise here that deserves further research.

Because when you’re the patient living with one of these conditions, “Well, we just don’t know,” or worse, “We haven’t been interested enough to collect the evidence,” simply isn’t a satisfying answer.

None of that makes carnivore a cure-all, but it does make it interesting.

The Scurvy Puzzle

When it comes to nutrient deficiencies, animal-based foods are incredibly nutrient-dense. One nutrient that often comes up, however, is vitamin C, which isn’t found in high amounts in most animal products. The big concern, of course, is scurvy.

So let’s talk about it and get into some surprisingly non-intuitive biochemistry.

First we will begin with some history. In 1928, the Arctic explorer Vilhjalmur Stefansson ate only meat for a full year under medical supervision at New York’s Bellevue Hospital and did not develop scurvy or any signs of nutrient deficiencies. In fact, he maintained excellent health. He learned this eating pattern from Inuit populations, who traditionally ate almost entirely animal foods for long stretches of the year, and yet scurvy was uncommon.

Why? The likely answer is two pieces of biochemistry most textbooks skip. Vitamin C and glucose are structurally similar and compete for the same cellular doorways. When carbohydrate intake is high, glucose floods those doorways and crowds out vitamin C, so you need more of it. When carbohydrate drops near zero, vitamin C faces less competition and is used more efficiently. That said, that’s the less interesting mechanism.

More interesting is the possibility that the body, under the right metabolic and nutrient conditions, can recycle vitamin C. I’ll spare you the multisyllabic names of all the enzymes and cofactors and introduce just one: an electron carrier called NADPH. On a very-low-carbohydrate diet, NADPH metabolism can shift in ways that may help support the recycling of antioxidants in the body, including glutathione and vitamin C. Put simply, your cells may get more bang for their vitamin C buck.

Other explanations are possible, but the biological details aren’t as important as the overarching theme: Under different environmental and dietary conditions, the rules of nutrition can change.

We live in a world fixated on recommended daily allowances and acceptable macronutrient distributions, laid out in neat little tables and charts that we imagine every human body will obediently follow—as if our livers, pancreases, and mitochondria read textbooks.

But put the body in a radically different dietary environment, and it’s remarkable how its biology can adapt to use available resources differently. That’s the broader lesson of the vitamin C story. It’s not about any one mechanism. You might expect people eating only meat to inevitably develop scurvy, yet that’s not what we observe.

Again, that doesn’t make carnivore a cure-all—but it does make it interesting.

What About Your Heart?

Now, we should probably address the cardiovascular elephant in the room.

Meat has long been vilified for being rich in saturated fat and cholesterol—which, as we all “know”—heavy quotation marks there—are bad for your heart. So, is a carnivore diet inevitably bad for cardiovascular health? Will it necessarily cause atherosclerosis, accelerate plaque buildup, and have you dropping dead of a heart attack?

No. The story is far more complicated.

On cholesterol: Dietary cholesterol has little effect on most people’s blood cholesterol, because the more you eat, the less your liver makes. That said, saturated fat can raise cholesterol. But that alone doesn’t translate cleanly into higher cardiovascular risk when the fat comes from whole foods. For example, a state-of-the-art review in the Journal of the American College of Cardiology concluded:

“Whole-fat dairy, unprocessed meat, and dark chocolate are SFA [saturated fatty acids]-rich foods with a complex matrix that are not associated with increased risk of CVD [cardiovascular disease]. The totality of available evidence does not support further limiting the intake of such foods.”

Additionally, an individual’s metabolic context matters. For example, a recent six-month, weight-loss-controlled randomized controlled trial assigned patients with obesity to a high-fat ketogenic diet, including breakfasts like bacon and eggs, a Mediterranean diet, or a low-fat, plant-based diet, including breakfasts like oatmeal and fruit.

Interestingly, the high-fat ketogenic diet—despite containing seven times more saturated fat and 46 times more cholesterol than the low-fat, plant-based diet—produced greater improvements in several cardiovascular risk markers, including insulin resistance, liver fat, and inflammation, while the other diets produced comparable changes in LDL and ApoB.

The authors concluded that the ketogenic diet had unique cardiometabolic benefits for people with obesity, despite its substantially greater saturated fat and cholesterol content.

The practical takeaway is that, for someone in this metabolic context, a breakfast of bacon and eggs may produce a more favorable cardiometabolic risk profile than a breakfast of oatmeal and fruit. That might sound heretical, but it’s also consistent with the evidence from this trial.

Let’s bring this home and give you a provocatively reasonable thesis.

So Who Is the Carnivore Diet For?

Carnivore makes the most sense as a therapeutic trial for people with treatment-resistant irritable bowel syndrome, IBD, or other gut conditions; for autoimmune disease that hasn’t responded to standard care; or for someone who needs a strict elimination diet, followed by gradual reintroduction, to identify food triggers.

It makes the least sense for people who are already healthy and thriving on their current diet, and for anyone unwilling to monitor the biomarkers and potential nutrient deficiencies that catch the trade-offs early.

None of this discussion around eating a carnivore diet is sensationalism. None of this is fearmongering. It’s curiosity and compassion—curiosity about a diet most of us don’t fully understand, and compassion for people who are suffering and need solutions faster than the medical mainstream can sometimes provide them.

Maybe we’ve been framing the carnivore diet wrong all along—it’s not a religion to join or a movement to mock—but a tool. A powerful one. Perhaps it’s not the right tool for many people, but occasionally exactly the right tool for the right person at the right moment in their life.

It deserves rigorous study, an open mind, and above all, curiosity.

Views expressed in this article are the opinions of the author and do not necessarily reflect the views of The Epoch Times. Epoch Health welcomes professional discussion and friendly debate. To submit an opinion piece, please follow these guidelines and submit through our form here.

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