When a friend of mine first mentioned the carnivore diet to me, I thought he was kidding. Are people really only eating meat, and expecting to be healthy?
It seemed like another fad diet geared at grabbing attention more than anything. After all, despite the many differences of various popular diets, the one thing we could all agree on is that eating vegetables is good for you.
Since Dr. Shawn Baker popularized carnivore a few years ago, thousands of people report that their health and performance have improved on an all-meat, zero-carb diet. Trying to keep an open mind, I did some digging into this Shawn Baker character and the diet as well, finally tracking him down at a recent keto conference for a podcast interview.
I’ll admit, during a recent podcast episode, Shawn Baker gave me a new perspective on an all-meat diet that definitely piqued my curiosity. We discussed the nuances of the carnivore diet, what the research does and doesn’t say about eating only meat, why carnivore dieters don’t get scurvy, whether organ meat is necessary on carnivore, and more.
Is there research on carnivore?
To be upfront: no, not really. Carnivore is so new (and so unusual) that nobody has studied it yet. Most of the claims about carnivore are speculative, or are based on people’s personal experiences.
That said, there is a fair amount of research on aspects of carnivore (just not the diet itself), and enough people report major success on a carnivore diet -- with individual blood work and lab testing that they make public -- that carnivore is worth exploring. The goal of this article is not to paint carnivore as definitely backed by science; it’s to give carnivore due consideration, address some common concerns about carnivore, and explore possible reasons it’s working for so many people.
The benefits of a carnivore diet
First off, there are a few aspects to carnivore that may explain why some people do so well on it.
It’s worth mentioning that the studies above were not done using carnivore diets -- they used keto diets or high-fat, low-carb diets, which means the results don’t necessarily apply to a carnivore diet. That said, the study findings seem to line up nicely with common benefits people report on carnivore -- fat loss, decreased inflammation, fewer cravings, more energy, higher testosterone, muscle gain, and so on.
So while there isn’t specific research on carnivore yet, you can form a decent (albeit indirect) theory for why people seem to do well on it.
But what about the downsides to carnivore? It seems like eating only meat could cause a lot of issues, ranging from nutrient deficiencies to heart disease and bowel cancer.
This is where I want to take a closer look at carnivore and explore some common concerns, one by one.
Does meat have enough micronutrients?
Meat alone will not meet your recommended daily intake (RDI) for many micronutrients. Meat is not a good source of manganese, folate, vitamin K1, and a variety of other nutrients.
However, a fair number of long-term carnivores (a year or more) report blood work that shows no nutrient deficiencies and no symptoms of nutrient deficiencies either. How is that possible?
A popular explanation in the zero-carb community is that your vitamin needs change on a carnivore diet. There’s research to back that theory.
A good example is vitamin A. Your body uses a large portion of dietary vitamin A to metabolize carbohydrates, and if you don’t eat carbs, your vitamin A requirements may decrease[*].
Micronutrient needs can shift according to metabolism. It makes sense that your body would run differently on a carnivore diet than it does on a high-carb diet, or even a standard ketogenic diet.
That said, there isn’t enough research on changing micronutrient needs to say definitively whether carnivore will provide all the micronutrients you need. If you decide to follow a carnivore diet, I highly recommend getting micronutrient blood tests for the first few months, to make sure your nutrient profile is in good shape.
Will carnivore cause scurvy from lack of vitamin C?
A related concern is that carnivore will cause scurvy from lack of vitamin C. You may have heard about 18th-century sailors losing teeth to scurvy after months of surviving on nothing but dried meat. It happened because humans can’t make vitamin C -- we have to get it from diet, and the best source of it is fresh greens, which are hard to come by when you’re out at sea for months.
It’s worth noting, though, that scurvy-ridden sailors were eating dried meat. Vitamin C is water-soluble, and drying out meat would remove any vitamin C that was present in fresh beef.
It turns out fresh beef has vitamin C -- about 16 mcg/g in grain-fed meat and 25 mcg/g in grass-fed meat [*].
That isn’t much vitamin C, but it could be enough. Plenty of people have eaten nothing but beef, salt, and water for well over a year without developing scurvy, symptoms of which should show up within 3 months of starting the diet. Dr. Shawn Baker is a good example -- he talks about carnivore, vitamin C, and scurvy in our recent podcast. Dr. Baker’s theory is that your vitamin C needs decrease when you cut vegetables out of your diet, and that the little bit in fresh beef is enough to keep you scurvy-free, as long as you don’t cook the vitamin C out by eating your meat well-done.
There’s some interesting research to back this idea up. People who went on a ketogenic diet had higher vitamin C levels than people who went on a moderate-carb diet, despite the fact that, when getting only 4% of calories from carbohydrates, it’s difficult to consume large amounts of vitamin C [*]. It’s possible that very-low-carb diets decrease your vitamin C needs.
That said, if you try carnivore and you’re worried about vitamin C, a daily supplement wouldn’t hurt.
Will carnivore cause heart disease?
Eating nothing but meat means you’re probably getting several times the recommended daily intake for saturated fat, and saturated fat intake is infamous as a risk factor for heart disease. Should you be worried about all that saturated fat?
In my opinion, no. I’ve written about saturated fat before. In a nutshell, I think the studies correlating saturated fat with heart disease are based on weak evidence and are unconvincing.
As a brief example, here’s where Americans get their saturated fat [*]:
- 37.5% of Americans’ saturated fat intake comes from pizza, grain-based desserts (cookies, cakes, and the like), dairy desserts (ice cream), processed meats, candy, chips, fries, pasta, and burritos/tortillas.
- Another 24.5% comes from “All other food categories.”
- Only 24.2% of Americans’ saturated fat intake comes from whole foods like beef, eggs, full-fat dairy, butter, and nuts.
This is why correlational studies are so tricky. Is it the saturated fat causing heart disease, or is it the sugar, refined grains, low-quality oils, etc? Or is it the high-fat, high-carb combo that’s so common in Western diets?
There’s a strong case that it’s the latter. A cool new study found that saturated fat intake actually improved blood lipid profile and heart disease risk in people who followed a low-sugar, low-carb diet for a year (people on a low-sugar, low-fat diet saw similar improvements) [*].
Saturated fat probably isn’t a concern, especially in the context of a low-carb diet.
Red meat, zero fiber, and colon cancer.
A variety of epidemiological studies have found that red meat correlates with an increased risk of colon cancer, particularly in developed countries [*].
However, no such correlation exists in Asia, including in regions where people, on average, eat far more red meat than Westerners do [*]. It’s possible that the correlation is thanks to a confounding factor, not meat intake (see the above pie chart).
But what about fiber? A high-fiber diet correlates with decreased risk of colorectal and colon cancer, while a low-fiber diet correlates with increased risk [*]. Do you need fiber to keep your colon healthy?
Evidence is pretty split here. There are a few cases for eliminating fiber intake:
- Avoiding constipation, gas, and bloating. Zero fiber intake completely eliminates gas and bloating and reverses constipation, which suggests that carnivore could improve your digestion, especially if you’re prone to constipation or bloating [*][*].
- Decreased risk of diverticulosis/diverticulitis. A low-fiber diet also correlates with a lower risk of developing diverticulosis -- a very common condition where sacs form along your colon due to weakness in your intestinal walls [*] (note that this is correlation, not causation).
- Decreased intestinal stress. Fiber is also an intestinal irritant -- because you can’t digest it, it passes through your intestines intact, physically rubbing against your gut lining, causing microabrasions [*]. That may not be an issue for the average person, but if your gut is sensitive (if you have IBS, for example), fiber can cause diarrhea and severe bloating and pain [*].
On the other hand, there’s also compelling evidence that fiber is good for you. Fiber feeds good gut bacteria, helping them crowd out damaging microbes in your gut, and those bacteria turn fiber into short-chain fatty acids that improve overall intestinal health and decrease gut inflammation [*][*]. Low-fiber diets, on the other hand, can promote the growth of damaging gut bacteria [*][*].
Is carnivore good for your digestion or bad for it? It’s hard to say. The effect may vary from person to person -- but if you find you have digestive issues after ~4 weeks of letting your gut adapt to carnivore, you may want to add some variety back into your diet.
Is there an evolutionary basis for eating only meat?
In our recent discussion, Dr. Baker put forth the idea that we evolved to eat plants out of necessity, because it was often hard for us to access meat. He argues that meat is a denser source of nutrition and that our bodies prefer it, but that it wasn’t always available, so we adapted by learning to digest plants as well -- even though plants are not optimal nutrition.
There’s some research to back this idea up. Humans absorb a variety of nutrients better when they come from animal sources. Iron, zinc, vitamin A, protein, and vitamin B12 are all nutrients that we absorb better when we get them from meat [*][*]. The same is true of omega-3s -- we readily absorb DHA and EPA, animal-based omega-3s, while we only absorb about 6% of plant-based omega-3s, and we have to convert them into animal form [*].
On top of that, plants contain antinutrients that actively block nutrient absorption, so while plants may have higher raw levels of many vitamins and minerals, your body might not actually be able to access them [*].
Today, though, we have steady access to a wide variety of edible plants, and cooking destroys most of those plants’ antinutrients. That means we can readily absorb the vitamins and minerals in vegetables, fruits, and grains. So even if all-meat diets were evolutionarily ideal for us in the past, that doesn’t necessarily mean carnivore is the healthiest diet today, considering our exceptional access to a variety of foods.
This is just scratching the surface of the link between evolution and carnivory. It’s a fascinating topic, and if you want to learn more about it, Dr. Baker and I discuss it in depth here.
My experience on the carnivore diet.
At the end of the day, without direct research, it’s hard to say for sure whether or not carnivore is healthy. Yet I felt that the rationale to components of the carnivore diet and a growing number of people are having success switching to an all-meat diet, there was a decent case giving carnivore a try.
So that’s what I did. For about 21 days, I ate almost nothing but grass-fed beef and organ meat, and fish. I added garlic, salt, pepper and other spices for taste, but really excluded the rest from my diet.
More energy, likely because I had no food sensitivity issues. In general, I’m a sensitive butterfly that is affected by a decent amount of foods. Even foods that are fine for most people, including avocado and dark chocolate. By making other foods not an option, I never had to worry if I was going to eat something that would drain my energy.
More productive. Because I was only eating meat, I really couldn’t snack on things between meals, which is quite nice for forcing better productivity, while also encouraging proper enzyme signaling and cellular autophagy.
Felt stronger. After adopting this new diet, I felt quite a bit stronger while lifting than I usually do, which allowed me to progress quite quickly through a back squat program I had been working on.
- Good digestion. Although some people report having nausea, diarrhea, and the keto flu while transitioning to carnivore, I felt pretty good basically the whole time without any digestive issues or malaise. Likely this was because I am already relatively keto-adapted, and I am very conscious about getting enough sodium in my diet.
Had to meal prep more judiciously. With very few restaurants during the middle of the day able to supply me with copious amounts of meat for anything less than a fortune, I had to meal prep well the night before. On the days I didn’t meal prep, I’d have no choice but to fast through the day. Ultimately probably a good thing for my health, but its often nice to mentally prepare for fasting better.
Slightly more hungry. Although many people who do carnivore report feeling quite satiated, I felt that only eating meat made me feel hungrier, despite the fact that I was eating enough calories. I can likely attribute this to the fact that the sheer volume of food was less, since meat is so much more calorically dense than veggies and fruits.
A bit boring. First off, I’m not a foodie. I like good-tasting, healthy food, but I’m usually fine with quite a basic diet without much variance. This should be believable since I started a healthy meal replacement company. So for a diet to be boring to me is saying quite a lot. But only eating meat for every meal got quite old quickly.
- Socially limiting. Even more so than with keto or paleo, it’s difficult to justify to your friends that even vegetables are off limits. It was often just easier to fast or eat much less during these occasions, which didn’t feel awesome.
Summary: although I felt good on it from an energy and health perspective, I did feel that the carnivore diet was quite limiting for my lifestyle, and didn’t make me feel quite as full as my previous diet. I’ve since transitioned back to a diet that includes veggies, sweet potatoes and berries, however, I have found that adding more meat into my diet has had a positive effect on my overall energy, focus, and strength.
Tips to trying the carnivore diet
If you want to try a carnivore diet and you’re not already fat adapted, you can expect many of the initial, adaptation-related side effects that come with a keto diet:
- Keto flu, where you feel weak and tired as your body switches from burning carbs to burning fat for fuel
- Diarrhea as your digestive system adjusts to a zero-carb diet
- Nausea from increasing your fat intake
These side effects should be temporary, and generally go away after two to four weeks on a carnivore diet. If they persist, carnivore may not be for you.
If you’re going to try carnivore, I suggest getting blood tests to make sure your micronutrients are where they should be. Pay careful attention to how you feel, too; if you’re having any strange symptoms, you may want to stop eating only meat.
And if you want the benefits of a low-carb diet without the restriction of carnivore, check out this beginner’s guide to keto. It tells you everything you need to know about starting a keto diet.
Thanks for reading!