The Carnivore Diet: Can We Live On Meat Alone?
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Hi, I'm Wendy Zuckerman, and you're listening to Science Versus. This is the show that pits facts against flesh. Today on the show, the carnivore diet. Fancy eating meat? A lot of meat?

This is day 312, eating nothing but meat, eggs, and seafood. 18 ounces of the chuck eye portion of the chuck roast. Beef, chicken, lamb, pork. Burgers and beef tallow. So good. Some say this diet is so good because it's

Others say it's the best thing they've ever done for their health. They feel more vital, their brain seems to work better, and their chronic illnesses seem to have disappeared. One big influencer here is Michaela Peterson. She's the daughter of the controversial author Jordan Peterson. And Michaela says that the carnivore diet cured her rheumatoid arthritis.

Here she is giving a talk about it. And I cut everything out except for beef. And two weeks after doing that, thinking, I'm nuts, hopefully I don't get vitamin deficiencies, the itch went away and my joints started to feel better. Four weeks after that, I stopped crying in the morning. And five months after that, the anxiety lifted and I was back in what I felt was heaven compared to how I'd been living. All beef, all lamb, salt and water.

Her dad went on the diet too. Here he is telling Joe Rogan about it a couple of months ago. I eat steak, and when I deviate from that, things start to fall apart around me pretty quick. This diet is blowing up right now. People cannot get enough.

- Y'all, I have never felt better. - My energy has been amazing. I have been sleeping so much better than I normally do. I don't get any bloating, gas, like my stomach issues are completely gone. - I was able to lose 90 pounds. My knee pain of over a decade went away. My mental health is the best it's ever been.

In fact, researchers did a big survey of people who have been on the carnivore diet for at least six months, asking them about their mood, hunger levels, weight and health. And tons of people reported that they loved this diet and it improved their health. But to a lot of us listening to this right now, the carnivore diet feels plain wrong. There's the environment to think about. Plus...

We've been told our whole lives that eating vegetables is good and eating loads of meat puts us on a fast track to crappy health. Stuff like heart disease and cancer. The carnivore diet is going to kill you. What is so terrible about this diet is the insanely high amount of saturated fats people are consuming. Do not embark on the carnivore diet unless you would like to get scurvy. Scurvy. Scurvy.

So who's right here? Can a carnivore diet really make you mean and lean? Or is this diet a big mistake? Because when it comes to the carnivore diet, it makes a lot of people feel... But then there's science. Science versus the carnivore diet is coming up just after the break.

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Welcome back. Today on the show, meat, meat, meat, meat. I'm here with senior producer, meathead, Rose Rimler. Hi, Wendy. So on this diet, people just eat meat, right? You can't eat any vegetables. Yeah, some people eat eggs and dairy too, but definitely no vegetables, certainly no carbs or bread or anything, but also like no broccoli, no spinach, no...

Yeah, because when it comes to this diet, I have seen people proudly taking photos of a plate of food that's like two steaks, two eggs, a sausage on the side. And then just for garnish, three blueberries. And they're like, carnivore diet. And all the comments will say, get that blueberry off your plate. Blueberries, no. No, I guess if you're a true carnivore, you're not eating any blueberries, according to the diehards. Yeah.

For some reason, they always showcase their food on cutting boards. Have you noticed that? Yeah. It's like a cutting board. I think because that's how T-Rex ate. Yeah. Ate her food, right? Yeah. I mean, your instinct would be this would wreak havoc on your body, right? Because it seems like you'd be missing out some very important vitamins, minerals, stuff like fiber, right?

If you get rid of all that from your diet, my question is like, will you be okay? You know, just basically, are these people okay? That's my question. Are these people okay? Yes, yes. Well, I talked to Karen Zinn about that. She's a professor at Auckland University of Technology in New Zealand. And I'm also a registered dietitian. So nutrition is my game, if you like.

Karen, like us, has been hearing more and more about people going on the carnivore diet. And she wanted to know if you go full meat, what are you potentially missing? So she and some colleagues analyzed the nutritional value of an all meat diet. Was there any glaring deficiency that that could pop up? Well, well, yes. Vitamin C, that would be the natural one. Where's, you know, where's the vitamin C?

It's not there. We need vitamin C to make collagen. And so without it, your skin and mucous membranes and blood vessels start to break down. That's why your gums can bleed? That's all I know about scurvy. Yeah, so we're talking about scurvy here, right. And your gums can bleed and it can get really serious. People can die.

And that wasn't the only nutritional deficiency that Karen was worried about. It looked like some other nutrients might be kind of low in this diet. For like

Potassium, where are these things? Folate you get from green leafy vegetables. Fruit and veg give you lots of potassium. So you ordinarily go, well, those things potentially do jump out. We need folate to make red blood cells and to keep our brains running smoothly. And we need potassium and other electrolytes for all our cells to make them, you know, just work. So not having enough of those things is a big deal. Right.

But this idea that you will not get them and will be deficient in these things on the carnivore diet, like from what we just talked about, that's all theoretical, just like written down on paper. It feels pretty non-theoretical, I'll say. Well, I mean, well, here's why I say it's theoretical.

We don't have many studies on the carnivore diet. It's pretty new. It's very specific. It's not like the Atkins diet or the paleo diet where you're restricted, but you're not that restricted. Like you can still eat lots of fruits and vegetables. So I kind of had to go digging. And I did find this amazing study that I am delighted to tell you about. It's a study of two Arctic explorers. Their names were Stephenson and Anderson.

Stephenson claimed that he had lived in the Arctic for months eating nothing but meat.

And he said that it had gone just fine. Back then, people were as skeptical as today about this. And they were saying like, you can't do that. You're going to have some kind of nutritional deficit or something terrible will happen to you. And so he and this other guy, they offered to be guinea pigs. So in the late 1920s, while they were in New York City, they started eating an all-meat diet. It was a lot like what you see people on TikTok showing us that they're eating. It was literally just meat, fish, vegetables.

And I think, was it, one of them didn't eat eggs either for the year. So it's literally just meat. And at first, it didn't actually go so well. And that was because the researchers wanted to know what would happen if these guys ate only very lean meat, so very little fat. And one of them, Stephenson, he agreed to do that. And when he ate that diet, he developed a lot of diarrhea. Yeah.

Yeah, I was reading about this. He felt awful. Yeah, yeah, absolutely.

Interesting. What was going on? Well, it's interesting because Stefansson actually knew in advance. He was pretty sure this was going to happen to him. He told the researchers about it, but he was like, all right, I'll try it anyway. Because he knew about something that's sometimes called rabbit starvation. It's also called protein poisoning. And that's basically when your diet is made up primarily of lean meat, like rabbit, you can actually get really sick. And we

We think that's because when someone is eating mostly protein, their body may not be able to convert that much protein into urine fast enough. So you get ammonia built up in your body. Oh.

Which is toxic. So, yeah. So after a few days of this, the researchers eased up on Stephenson. So what they did was they added fat to the meat. So they changed the type of the meat and they added more fat to it. He came right within a few days. So adding more fat to the diet brought down the protein, you know, just because the percentage of protein got lower because the percentage of something else got higher. Yeah.

And so he got a lot better. And then in the end, both of these guys stayed on the diet for a full year. If these guys were going to get scurvy, they would have got it. I mean, they had 12 months of doing this. They would have got neurological issues from not having the folate. They would have got all sorts of deficiency states, rickets that you get from not having some of these nutrients. But at the end of the year... Everything was just normal. There was nothing...

there that was a little bit untoward

They were all intense. They were healthy, two healthy individuals who had good vitality. All their organs, all their systems, all their everything was in good working order and totally good as gold. And so no deficiencies? No vitamin deficiencies? Not as far as anyone could tell, which is interesting. It is interesting. So why not? Well,

Well, for scurvy. So one hypothesis is that if you eat a lot of meat, you get a lot of this nutrient called carnitine. And maybe carnitine does some of the same stuff in our bodies that vitamin C does. And so that would mean we would need less vitamin C. That's a hypothesis. It has not been tested as far as I can tell. And we also know that fresh meat actually does have a bit of vitamin C in it.

In fact, studies have found that some of the traditional meat foods that are eaten up north by people native to that region, like whale skin, they're surprisingly good sources of vitamin C. But most people on the carnivore diet, I mean, including this Stephenson and Anderson, right, they weren't eating whale skin, were they? No. They were probably eating organ meats, though, like liver, which does have a little vitamin C in it. And it has other micronutrients like folate.

But another explanation for why these people were okay is that maybe if you don't eat any carbs at all, your body can adjust in these really interesting ways. Like how? So, for example, with Foley, even if you are a carnivore,

who's like, ew, I don't want to eat liver. What we have seen is that people on really low-carb diets, their gut bugs start pumping out more folate. So in some ways, the body can kind of adjust in certain circumstances. Oh, that's cool. So you think people on the carnivore diet, maybe they won't get these deficiencies? Well, I mean...

I realize the evidence I presented is maybe not the most convincing. It's a hundred-year-old study of two people. It does tell us something and another thing to

Another thing to consider is that we know for thousands of years there have been people living in high-latitude places where not much grows eating an animal-based diet without glaring deficiencies. Uh-huh. On the other hand, people eating these traditional diets would also have eaten non-meat stuff when they could. They would eat berries, other plants. They would eat kelp. Right. No one was shitting on them on Instagram if they were eating some berries. Yeah, I think so. I think if everyone who went on the carnivore diet got scurvy...

it would not be getting more and more popular. We wouldn't be hearing about it as much. So I think it's possible to live...

on a meat-only diet and avoid glaring deficiencies. But Karen says like, look, we don't really know what's going on here. If you want to do this, please take a multivitamin. I really don't want to say, well, let's see if you manifest a deficiency and then we can patch it up with some, you know, vitamin C. You don't want to be like, well, if your gums start to bleed in a few weeks, come back. Give me a call. Yeah, exactly. Exactly. The other thing that seems obviously missing here is fiber.

And you'd expect people eating no fiber would be constipated. But Stephenson and Anderson said that their bowel movements were fine. In fact, the scientists actually collected their stool and said not only were they fine, they were great. It was like it had no odor whatsoever.

And it's kind of funny because like there's that expression like, oh, he thinks the shit don't stink. And like, wow, they really don't stink. Totally. The paper does say that their poops were actually smaller than average, which does make sense if there's no fiber to bulk it up. Yes, that's right. You start veering towards the little kangaroo poos.

But it's not just about poop because fiber is very important for a bunch of other things. It can lower your risk of heart disease, lower your risk of colorectal cancer. I mean, what? Well, this all brings me to my next question, which is, okay, maybe these people are okay, surprisingly okay in the short term, a year, whatever. But what about long term? What are the long term risks? Yes. So let's start with heart disease. Yeah, right.

I think this is like a really visceral fear people have of this kind of diet, of eating so much meat. Because when you're eating a lot of meat, you're probably eating a lot of saturated fat and cholesterol. And a lot of us just have this like, bleh, feeling about that. Like, ooh, so much grease building up in your body. I think that's why this particular case report went viral recently. Man on a carnivore diet starts...

oozing cholesterol from his skin. - Can we please just talk about how unhinged it is that people on the carnivore diet are eating so much fat and cholesterol that it is leading to a visible buildup of fatty deposits under the skin.

Yeah, this guy had been on the carnivore diet for eight months. He showed up to the doctor because he noticed something interesting. I'll show you some pictures, Wendy. Oh, was he turning yellow? Like an egg yolk? Because an egg yolk's full of cholesterol, right? Pretty much, yeah. Scroll down and look at the pictures of his hands.

Oh, yeah. It's like if you imagine the sort of creases on your palm and all those creases are basically the color of an egg yolk. Ooh. It wasn't actually oozing out of his skin. It was just built up under it. Okay.

That's fine, then. Well, this got reported as, like, look at what the carnivore diet will do to you. But I think that's unfair. In addition to the not oozing, it was also probably a genetic condition this guy had where his body couldn't clear out cholesterol very efficiently. So this is kind of, we expect this to be rare. This is not going to happen to most people on the carnivore diet.

Okay, so all right, well, that's good news. But will they eventually get heart disease? Right, that's a more reasonable thing to worry about. And the reason that idea is out there is because a lot of us have heard that when you eat a lot of saturated fat, cholesterol, it'll clog your arteries and that will kill you. Now, these days we know that that old story is not quite true. It's actually a lot more nuanced than that. Mm-hmm.

But some people on the carnivore diet will take this a step further. And they'll say, not only will it not increase your risk of heart disease, it should actually protect you from getting heart disease. Oh, how? How? Well, they say that this diet is really good for your blood sugar. And so you're not going to end up getting diabetes, type 2 diabetes. And therefore, you're not going to get heart disease, which comes with type 2 diabetes. Is that true? Does the carnivore diet...

protect you from diabetes and getting heart attacks? Well, okay, it's true that diabetes increases your risk of heart disease. It actually doubles that risk according to the CDC. But as far as does the carnivore diet have a protective effect on your diabetes risk? The thinking here comes from the fact that this is a low carb diet, right? I mean, it's actually a zero carb diet.

So, as I mentioned, we don't have much in terms of studies on the carnivore diet specifically, but we can look at studies of other low-carb diets to get some clues here. And those studies do find that cutting out carbs can improve people's insulin sensitivity and have even been shown to reverse diabetes in people who already have it. That's cool.

But that's just part of what this diet is about, right? You cut out the carbs. But what about eating all that meat? I mean, what happens to your heart disease risk when you eat all that meat? Well, that's the thing. When researchers have compared people on a low-carb diet who eat a lot of meat versus people on a low-carb diet who eat a lot of plants, guess who does better? Plant eaters. Yeah, the plant eaters. They do better. Okay.

So that led a group of heart health nerds who looked at that study and they put a lot of other evidence together to

They concluded that it's okay for people to follow low-carb diets for their hearts, but if they do, their doctors should, quote, encourage the consumption of vegetables, fruits, nuts, seeds, legumes, and whole grains. Fervorant, fervorant. Do you know how much they're going to shit on you on that carnivore diet subreddit if you stop increasing your consumption of vegetables, fruits, nuts, seeds, legumes?

And hold grains? Maybe they'll ease off. I have some good news here for the carnivores. It's about cancer. So when I looked at the link between red meat and cancer, that's squishier than I expected it to be. The best evidence that meat is linked to cancer is for processed meats. To these influencers' credit, they seem to be promoting eating freshly prepared meat.

And that is probably less risky when it comes to cancer. Okay, so here's where we're at.

These risks that people are concerned about with the diet around vitamin deficiency and heart disease and cancer, it's not as if these risks are total garbage and this diet is 100% safe. There still could be risks here. We're just not entirely sure, which means that the benefits, it's all about how good the benefits are. Yeah, to outweigh these...

It's potent. Exactly. So after the break, the benefits. Welcome back. Rosemary Mellon. People say they feel amazing on this diet. Tell me about it. I want to hear the good stuff. Yeah, I want to start with people who say this diet has healed their guts because

Because some people who decide to do this diet are doing it because they're in really bad shape, like in terms of their GI stuff. I talked about this with Adrian Sotomota. He is a doctor and a researcher at Tecnológico de Monterrey in Mexico City. He sees a lot of patients with inflammatory bowel disease. That is a group of conditions that includes Crohn's disease and ulcerative colitis and

And it's just, it's just awful. It's among the most, you know, discapacitating diseases. Makes everything harder. It makes going to work harder. Makes, of course, eating harder. Even mild forms of IBD are still, you know... Really suck? No joke. Not a walk in the park.

People's guts are inflamed in these conditions or they get ulcers on their intestinal walls and it can cause a lot of pain, cramping, bloating, vomiting.

Diarrhea. Adrian's heard about people who get diarrhea 12 times a day, often with blood in it. And sometimes people get anemic and they need blood transfusions. Oh, gosh. I know. And while there are medicines for it, they don't always work for everybody. Adrian says IBD is... Stubbornly persistent.

But then Adrian started hearing about people going on the carnivore diet for their IBD. The first thing I felt was curiosity. The second thing I thought was, I mean, of course, deep work. So he and a colleague started collecting stories from these people. And they ended up with 10 case reports from people whose IBD had been stubbornly persistent. And... Many of them used drugs.

Besides life-changing, another patient called it a miracle. Miracle? Wow. So how is this diet helping them? Well, one explanation that I heard again and again online about why this diet might be so good for you is basically because plants are toxic.

Plants are loaded with things that are designed to hurt us. Plants do not want to be eaten. They're going to defend their leaves, their stems, their roots, and their seeds. Lectins, phytic acid, oxalates. When you put that oxalate, those vegetables, into your body, your body then recognizes it as something that it needs to fight against. The thinking here is that plants make chemicals to defend themselves against diseases or getting eaten by bugs, bugworts.

They'll use stuff like tannins, oxalates, et cetera, and that those chemicals are bad for us. And frankly, Wendy, this is the most irritating part of the whole carnivore diet spiel that I see online because I think it irritates me because it's like plants are being framed for a crime that they didn't commit. Oh, so what is what's happening here?

I mean, as always, these influencers are taking little grains of truth and blowing them up. So, like, yes, there is some stuff that can be toxic in plant foods, including some stuff that some might call anti-nutrients in plants that they can interfere with us absorbing certain nutrients. Right.

But most of these things either break down when they're cooked or they're in very small doses or they just don't matter that much as long as we're eating a generally healthy, varied diet. I mean, that makes sense, right? Like spinach, carrots, they're not toxic. They're not toxic, right? No, they're not toxic. Yeah. I mean, to throw the carnivores a bone...

Maybe some people are uniquely sensitive to these chemicals. And like going back to our IBD people we just heard about, maybe their guts were really reactive to stuff that's in plant foods. But that doesn't mean that everybody should throw out our vegetables and call them the enemy. Because, I mean, I also found a case series where people with IBD switched to a vegan diet, literally the opposite all plants.

And their IBD cleared up too. Oh, okay. Despite all the tannins and oxalates and lesion that they were eating. Right. What's the thinking here that these bowel conditions are caused by an array of different things potentially? And if you...

Personally, maybe you are a little sensitive to some of the stuff in vegetables and then cutting them out of your diet actually might help. But on the other hand, you might be someone who's sensitive to the stuff in meat and then a vegan diet is going to help you out. Is that the idea? So there's no miracle IBD diet? Yeah, there's probably no one IBD diet to heal them all. Although the typical Western diet full of ultra processed foods is best avoided, there's

But beyond that, we really don't know. Actually, one review paper I found said that it basically comes down to if it hurts, don't eat it. Okay. All right. But I guess if you are really suffering and have tried a bunch of things, maybe give it a go, I guess, with the risks that we talked about at the beginning of the show in mind. If I was shitting blood every day, yes, I would try this. And everything else hadn't worked, sure.

All right. So from not shitting blood to other benefits. Yeah. People talk about stuff like the carnivore diet curing arthritis, psoriasis, a lot of autoimmune stuff, actually.

And people will also say it helps them with brain fog. And that could also be an autoimmune issue. Uh-huh. And maybe, like I said, some people are uniquely sensitive to something in various plants. And this diet functions basically as an elimination diet for these issues. But there may be another explanation. The carnivore diet is also a ketogenic diet. You know, in a ketogenic diet, you might have a steak and a side of broccoli. On this diet, you're just having the steak.

Either way, you're going to wind up in ketosis. Yes. Yes, yes, yes. Which is where your brain and your body starts using this chemical called ketones for energy rather than using sugars, which is what it mostly runs on. And there is some evidence that for some people going into ketosis tamps down their inflammation.

It might have to do with one of the ketones that your body makes, BHB. It's thought to be an anti-inflammatory agent. So I don't think there's anything special about the bucket loads of meat for people who are seeing a benefit with this diet. I think it could be that they're just in ketosis, which for some people, they feel really good in ketosis.

Right. And so that's very helpful news that if you are going all the way on the carnivore diet, you can have some vegetables and probably still stay in ketosis. Yeah. Experts told me that if ketosis is the thing that's making you feel good, you don't have to go on such a restrictive diet to get there. Bottom line, you don't have to be this hardcore. The whole hog. Right. You don't have to go whole hog.

Also, Wendy, a lot of people lose weight on this diet, and that could be why they feel better because, you know, weight loss can sometimes help with chronic diseases. That makes sense. And then as far as why you might lose weight on this diet, you know what? Let me guess, Rose. If you are restricting what you eat in such an extreme way that not only are you not eating muffins and cakes, but you've cut so many things out of your diet that

chances are you will lose weight because you're eating less calories. Is that right? That's what I would expect. That's what experts told me. There's no studies of weight loss on people on the carnivore diet. We could look at studies of people on the keto diet if we want. That's probably the closest we can get. And there's a meta-analysis that found that on the keto diet, people lost on average about 11 pounds over at least a year. But...

Yeah, Wendy, I think it's as simple as that. So we've talked about people with specific conditions giving this a go, but I guess for the rest of us who are just trying to live our best, healthiest lives, do you think the carnivore diet is a good idea? No, I think it is a very stupid idea.

Okay. That's because studies have shown over and over again, thousands and thousands of people that eating plants is good for you. My favorite of these studies is the Seventh-day Adventist studies. They followed people who were either vegan or vegetarian or vegetarian except they ate a little fish or they were meat eaters.

And it turned out that everyone who avoided meat, even if they ate a little fish or a little dairy, they had better health and they lived longer than the meat eaters. So the more veg, the better, essentially. Yeah, and those studies are huge, right? Yeah, this one, um...

This one in particular was like 70,000 people. And compare that to two Arctic explorers who just didn't get scurvy, you know? Yeah. All right. Not to mention the environmental issues around eating a lot of meat, right? Yes. And some people in this space, they argue against this. They say eating meat isn't actually that bad for the environment. That's a myth. Or they'll say like, it's okay as long as you eat grass fed meat or you get meat that's farmed via regenerative agriculture. Yeah.

We looked into this. And, you know, Wendy, I just want to pull something out of the science versus storage closet that we haven't used in a while. It's a little dusty. Hopefully it still works. No, that's not true. Meat eating is bad for the environment. Full stop. Meat and dairy account for at least 12% of the world's greenhouse gas emissions. Wow.

Grass-fed beef, this surprised me. It might actually be worse for emissions than feedlot-raised beef. And that's basically because grass is a less efficient feed. And then when it comes to regenerative agriculture, it's not anywhere near ready to offset the emissions caused by feeding and raising livestock. All right. There you go. The risks to the environment are known. And for that alone, for me anyway...

You got that sound effect again. I'm going to give the carnivore diet a... Thanks, Rose. Thanks, Wendy. How many citations are in this week's episode? This week there are 100 citations. And if people want to see these citations, read more about meat, meat, meat, meat. Where should they go?

They can check the link to the transcript and they'll find that in our show notes. Excellent. All right. I'm hungry. Let's eat, Rose. Bye.

Thank you.

Science Versus is a Spotify Studios original. Listen to us for free on Spotify or wherever you get your podcasts. And wherever you do listen to us, give us a five-star review if you like what we're doing. It helps others find the show. But if you are listening on Spotify, then to follow us, tap the bell icon so you get notifications when new episodes come out. I am Wendy Zuckerman and I'll fact you next time. ♪