Disclaimer
I'm not qualified in any way to provide health or nutritional advice, so any opinions expressed are just my own thoughts from the information I've come across. I also can't guarantee the accuracy of the information I've come across or anyone's interpretations of that information. I would also like you add that I am not advocating for any particular way of eating, but rather trying to analyse and figure out why certain diets might be making people healthier or sicker. Here I am looking at this purely from a nutritional standpoint rather than an ethical one.
It seems the carnivore diet is becoming more prominent of late and from the experiences of those who have taken to it, it's turned their lives around, often from chronic and life threatening illnesses. But why is this, when until fairly recently people thrived on mixed diets with plenty of plant foods in them? We never had the levels of chronic metabolic and autoimmune issues we have today. Why is a carnivore diet proving so effective for some of the worst cases? Even those who are experiencing these improvements don't really understand it, particularly as we're so often being told that red meat is bad for us. It's often indicated as a culprit in increasing heart disease and cancer, yet these are some of the things that people are apparently healing from with this diet.
What's Happening to our Guts
I believe the clues to why this diet is working so well for some are likely within the gut. In recent years we've been hearing more and more about the gut microbiome and it's importance in our immune system. They're actually discovering that it also communicates with our brain and may very well interact with and affect how our entire body works from hormone production to metabolism. But let's take a step back to its basic functions to look at where things might be going wrong.
A healthy small intestine has no microbiome, this should only be in the large intestine. Therefore when food comes through from the stomach into the small intestine only easily digested foods can be absorbed into the body at this point. Meats and animal products are fairly easily absorbed here while whole plant foods aren't as easily digested so they move on into the large intestine where the microbiome can start feeding on them and breaking them down for us to then absorb.
If we've got a good, healthy microbiome then all is well and good and we shouldn't experience many issues. Unfortunately, for the last half a century or more this bacterial colony in our guts has been under attack. The introduction of broad spectrum antibiotics exposed us to antibiotics that didn't discriminate good from bad bacteria. Artificial sweeteners kill our gut microbes, manmade emulsifiers damage our gut mucosal lining and ultra processed foods feed and encourage the multiplication of bacteria that cause harm rather than health to our bodies. It doesn't stop there either because even pesticides and herbicides kill our gut bacteria and then there's the harm that plastics and other toxins we can no longer avoid completely in our day to day lives do.
In addition to assisting the digestion of food the gut microbiome helps to protect the cell wall of the gut by producing that mucosal lining. The cell wall itself is just one cell thick and therefore very easily damaged if exposed. Some plant defensive compounds, such as lectins, will damage this exposed cell wall. The fact that we developed a microbiome is what made us more capable of eating plants, coping with their defensive toxins and able to adapt to such a wide range of climates. Some cultures eat plants almost exclusively and have thrived, until they encountered the modern western diet.
Ultimately, damage to the gut cell wall leads to leaky gut which is at the root of most chronic diseases, particularly autoimmune ones. After all the main part of the immune system sits on the other side of this wall ready to try and repair any breaches which will occasionally happen even with a healthy gut. It's bound to get overwhelmed with constant breaches, however, and go over active.
The Pros and Cons of Carnivore
With this information in the background I set out to look at the for and against arguments of eating an only meat diet.
The biggest argument for eating meat is that its nutrients are in a form that are easy to digest and they are in a form that our bodies can use straight away so it doesn't need to convert them. It lacks any plant fibres that would interfere with absorption in the small intestine, so even with a damaged microbiome you're going to get the nutrition you need while giving your gut more time to heal. Fasting is actually one of the quickest ways to rest the gut allowing it to repair, but carnivore seems to be the next best thing, because you can't fast forever.
This brings up the first argument against carnivore eating: we need fibre don't we?
Well, not really. People with inflammatory bowel disease, such as crohn's or ulcerative colitis, can struggle with fibre. We can't actually digest it ourselves, it's our gut microbes that feed on it. So it's great food for them, but if those bacterial colonies have been decimated it can take time for them to recover. Then if the gut is badly damaged as well, our digestion may never be as healthy as it could have been. Fibre can also tie up some of our nutrients, which can be a good and a bad thing. If it's sugars then it's a good thing because it will slow their absorption rate reducing glucose and insulin spikes. If it's protein or other vital nutrients, then it isn't so good, especially if our microbiome is too damaged to break the fibre down to help release it again.
Juicing vegetables is a way to get their nutrients into a form that is more easily digested, however, those nutrients will often still be in a form that the body needs to convert in order to make use of them and the juice will still have anti-nutrients that a damaged gut biome and some organs could struggle with. For example oxalates can be concentrated with juicing and they can cause kidney damage, particularly if you already have kidney problems.
Another common argument against eating only meat is that we can't get all of our micronutrients (vitamins and minerals) from it. Incidentally this argument is also one which is often used for eating only plants.
It turns out that this argument is a fallacy, because meat does, in fact, contain all our essential nutrients in a form that we can readily use, even vitamin C, as long as it's not over cooked. So if you don't like your meat rare then yes, you should certainly look at getting nutrients damaged by heat from other sources.
For those eating only plant foods they would likely need to look at eating a broad range of natural foods to access all their vital nutrients. Many of the plant based essential nutrients are in a different form to those in meats, so we need the enzymes to be able to convert them to a usable form. Some people are well adapted to this, while some aren't. Likely more people are less adapted today than ever with all the gut and mitochondrial damage we have from our lifestyles and environment.
Something else that often crops up with regards carnivore is the fear that it's too high in cholesterol, so it could increase the risk of heart attacks. This is leads to another entire topic on its own, but research is coming out which actually says otherwise and the studies which seemed to point to this have been shown as having little real evidence of this. It looks like it's much more complex than just one factor and the short version is that it's the smaller, denser LDL cholesterol molecules which cause plaques and not the large ones that we get from meat.
Then an argument against long term carnivore and keto in general is the belief that carbohydrates are essential for energy. After all, carbohydrates give us glucose and our bodies use glucose for energy. While it's accurate that we use glucose for energy, our livers are quite capable of making it for us from other sources, for example fats and proteins. We can also use ketones for energy and some consider this the preferred energy source for our brains. Ketones are made from fats, not carbs.
Now it does seem that if you are in a purely ketogenic state for a long time and then at some point eat a small amount of carbohydrate when your body isn't used to it then you will likely get an excessive insulin production reaction to it. For the most part this will settle down if you continue to eat carbs as your body readjusts, assuming you are metabolically healthy enough to do so. However, if you're diabetic then it could be a huge problem, so it's certainly something to be aware of.
Some Further Thoughts
For various reasons some people seem horrified at the idea of eating only meat and will get aggressive towards anyone suggesting it. However, when there are people for whom this way of eating has given them some semblance of a normal, pain free, discomfort free life I'd find it hard to condemn them for choosing that way of eating. An extreme case is Mikhaila Peterson whose autoimmune conditions made her life hell.
There are others who've found that eating carnivore has stopped them from constant cravings, always thinking about food and feeling hungry nearly all the time. I've actually seen people suggesting that carnivore isn't the answer for them, they just need to use more willpower. Yet when you hear these people's stories, often they've had shocking eating disorders and the relief they felt from being released from them is very apparent. As one person said, if you're calorie restricting for a period of time that you know there will be an end to you can cope, but when it's for life then it wears you down. It also works less as you get older, so you have to then restrict further. This observation comes from Dave McLeod, an incredibly driven and strong willed climber who spent many years trying to control his weight in just this way until he tried the carnivore way of eating.
When people express concern about the long term implications of eating only meat it's often pointed out that people like the Inuit ate that way throughout history, because few plants can grow in regions that are frozen for most of the year. While it's accurate that most of their diet came from meat and fish, they did occasionally have berries and would also eat seaweed. So they weren't 100% carnivorous, but their metabolisms would still have been in a state of ketosis pretty much all their lives.
Then just some final thoughts on raising children as carnivores from babies. There are some parents who are doing this after going over to a carnivore diet themselves. So far they have all said their children raised carnivore from the start have done substantially better than their other children developmentally, hitting milestones earlier than average and showing high intelligence; but I've come across plenty of parents who boast this of their children anyway. While I have no issue with someone else's choices on how they raise their children, I personally wouldn't go as extreme as carnivore for a healthy child, but would certainly consider a paleo diet, knowing what I know now. This would cut out most anti-nutrients while also giving adaptation for a broader diet. After all, when we look at all of our ancestors across the world they were all omnivorous somewhere along the scale, whether more towards meat or plant based.
What are your thoughts on this topic? Do you find it as fascinating me?
Another article of interest on this topic: