The Case Against The Carnivore Diet

Worse Than Unsupplemented Veganism

1. Introduction

A friend tried to persuade me to switch to the carnivore fad diet by sending sent me some videos to watch by a quack doctor named Anthony Chaffee. Although I was skeptical of the videos, I watched them anyway and I wrote this rebuttal essay in response. Some of the videos brought up interesting topics, but I see them more as examples of how easy it is for belief networks to use intuition for forming coherence, while rejecting scientific consensuses. For the most part, the videos were a waste of time, aside from the research that I did afterwards to evaluate their claims.

Carnivore diet proponents tend to rely on pseudoscience and anecdotes to support their claims, but I don’t care about anecdotes. Anybody can say this anecdote or that anecdote to support whatever they want to believe. I only care about statistics. The only thing that anyone could say to convince me to try the carnivore fad diet is if they had a larger body of statistics proving that carnivores live longer than people who eat Mediterranean or plant-based diets, contrary to the current consensus in nutritional science.

2. Nutrition

It’s not true that humans can get all of their nutrients from eating meat (or at least the kind that most people think of) (e.g. Vitamin C, flavonoids, dietary fiber, et cetera). The Innuit diet is ~99% meat, but it should not be mistaken as being the same as the carnivore diet. The Innuit are able to get all the nutrients they need because they eat all the organs of the animals that they capture, not just the muscles. Since many animal organs aren’t present in most grocery stores and supermarkets, it’s not possible for most people to only eat meat and get all the nutrients they need. The Inuits also have a mutation that prevents them from going into ketosis, so they won’t die when they are unable to find food. Most humans don’t have that gene.

From what I’ve seen, the proponents of the carnivore diet don’t focus too much on how eating meat can enable us to get all the nutrition that we need. Yes, they may point out specific nutrients that are abundant in meat and the benefits of those nutrients (e.g. Zinc, DHA, Vitamin B12, Iron, Vitamin B6, etc), but any proponent for any fad diet could do that too (e.g. the corporatocracy-backed 3-cup-of-dairy-a-day advertising gimmick that repeated “dairy products contain calcium” to get people to buy more dairy products). What’s really important is how we ensure that we can get all the nutrients that we need, not just point to a select handful, at the expense of ignoring others. Furthermore, a healthy diet should be able to identify which foods one would need to eat specifically to acquire each of the nutrients necessary for being healthy.

Eating red meat likely correlates with a greater risk of colon cancer and gout, but further research will be needed to confirm this. The healthiest meats / animal products to consume are poultry, fish, seafood, and eggs.

Excluding entire food groups (i.e. fruits, vegetables, nuts, grains, fiber, etc) is also socially restrictive, and likely to prevent humans from gaining all the nutrition that they need. It’s ridiculous that carnivore proponents claim that the vegan diet is “socially restrictive” when there are carnivore influencers like Meatrition who promote avoiding all the aforementioned foods. Carnivore proponents also tend to be against seed oils, but this opposition is irrational. See:

Furthermore, I don’t believe that most of the carnivore influencers truly adhere to their claimed diet everyday. Shawn Baker’s followers once spotted some apples and bananas in his kitchen once. It’s highly unlikely that any true carnivore could sustain the diet for long without experiencing eventual health problems.

The evidence in demonstrating any health benefits for the carnivore diet is lacking. By comparison, the Mediterranean Diet has been used for thousands of years, and has consistently correlated which good health and low rates of disease throughout all that time.

Most keto influencers sell supplements — Figure 1: Most carnivore/keto influencers sell supplements. Fad diets are scams.

2.1. Saturated Fat

Excluding carbs from one’s diet typically requires increasing intake of protein and fat (saturated or unsaturated) in order for someone to get enough calories each day. Since carnivores typically consume more saturated fat and excess sodium, both of these factors increase the risk of diabetes and cardiovascular disease.

Humans who lived a meat-heavy hunter gatherer lifestyle had more exercise than humans who lived an agricultural lifestyle. This would’ve compensated for the negative effects of eating the high amount of saturated fat in meat by countering harmful LDL chloresterol levels. Low-carb diets are also associated with shorter lifespans, especially if they’re done for long terms and the dieter is already at a healthy weight.

The carnivores have absolutely no evidence that increasing one’s intake of saturated fat will lead to health benefits. Many of the influencers know this, but they pretend that saturated fat won’t clog people’s arteries anyway. Consider how Amber O’Hearn (a carnivore influencer) repeatedly evaded questions about saturated fat instead of answering them.

2.2. Regarding Weight Loss

Eating a low-carb diet can help people lose weight. Carbs are a basic nutrient your body turns into glucose, or blood sugar, to make energy for your body to work. A low-carb diet, like keto and the early phase of the Atkins Diet, triggers your body into nutritional ketosis. Your liver starts to make ketones – a fuel that kicks in when your body doesn’t have enough sugar to run on – by breaking down fat. To bring about nutritional ketosis, extreme low-carb diets cap your carb intake at less than 10% of your total macronutrient (carbs, fat, and protein) intake. That translates to 20 to 50 grams a day of carbs. Low-carb diets generally shoot for under 26% of nutrition intake, or 130 grams.

Low-carb diets also tend to be much higher in protein than low fat diets. Protein can reduce appetite, boost metabolism and help people hold on to muscle mass despite restricting calories.

The general key to losing weight is to burn more calories than one takes in. It’s that simple. Theoretically, any diet could encourage weight loss as long as caloric intake stays low while the subject gets plenty of exercise. But there are reasons why a carnivore diet may be more effective for weight loss. The high-protein content of the diet may be responsible for most of the carnivore diet’s health effects. Even then, plant proteins are more preferable to animal proteins for reducing the risk of cancer.

2.3. Why Fiber Is Necessary For Human Diets

The idea that fiber isn’t necessary for healthy diets is a misunderstanding of the fact that “Humans can’t gain nutrients from fiber”.

Carnivores don’t eat plants, so they don’t get fiber.

Correct. Instead, carnivores eat bones, feathers, and fur along with the meat they consume, which basically serves the exact same function as fiber. Now obviously, humans should not be eating bones (specifically cooked bones), feathers, or fur, so humans still need a way to get the benefits of fiber if they try the carnivore diet.

If your goal is to just live, then yes, humans don’t need fiber. However, avoiding fiber in the long-term will negatively affect anyone’s health and lead to disease. Low fiber can make you constipated and increase chances of certain cancers, heart disease, diabetes, etc.

If your goal is to live well and long, then fiber is essential, as it provides healthy digestion and healthy gut microbiota, which is essential to overall good health. Those good gut bacteria produce valuable post-biotics that can help with regulating immune function, fixing leaky gut, and fighting chronic inflammation. Fiber also slows digestion, which helps with satiety. This can help people eat less and in turn keep a healthy body weight, which will improve overall health.

Fiber is an antinutrient because it prevents people from absorbing nutrients.

It’s true that the body does not absorb nutrients from fiber directly, but it is critical for your microbiome. The best predictor of a healthy microbiome is to have a diet with a highly diverse set of plants because it provides a diverse set of fiber for our gut. Our microbiome is critical because it regulates our immune system, levels of inflammation, anxiety, and other critical attributes of health.

Low fiber is recommended to help cancer patients to relax their gut and have it do less work. If fiber is recommended against in a harm-state scenario, then that implies that it’s a bad thing.

There are no logical requirements that necessitate that conclusion from the premises. There are also some foods that are not recommended for pregnant women, people with epilepsy, etc that can be beneficial in other scenarios, so just because some foods may be recommended against in strained or dire bodily states, that doesn’t imply anything.

3. Environmental Sustainability

A diet that is heavy in red meat and/or dairy products is taxing on the environment since cattle require much more food and thus require much more land than what’s required to raise poultry or fish.
There is no evidence to support the claim that using pesticides and such for growing crops would require killing more animals and rodents than what is required for raising and eating animals. If it’s true that raising cattle and such requires a lot of farmland for growing crops, then raising cattle should require killing more rodents as a side effect.
In any case, I don’t care too much about how different foods and farming practices require killing more animals than others. I’m concerned with which foods are the healthiest. Being less environmentally harmful is a bonus.

4. Response To “Plants Are Trying To Kill You”

I wrote this list of bullets in a response to Anthony Chaffee’s video Plants are trying to kill you, which promotes the supposed benefits of the carnivore diet and the so-called “Modern Toxin Theory of Disease”.

All the examples of toxicity in plant-based foods were obviously cherry-picked. It’s true that many plants have lots of toxins, but we should just be careful about what chemicals get placed in our food in general. For example, there is much concern over talcum powder and overly high doses of fluoride in foods, along with other chemicals whose names are too complicated for me to remember.
Given that some plants rely on animals to disperse their seeds, there are many plants for which it wouldn’t make sense to carry toxins.
Even if inedible plants have lots of toxins in them, this shouldn’t matter much because humans have been selectively breeding crops and such for literally thousands of years. Especially with GMOs nowadays, it’s hard to believe that toxins would still be as abundant in our food as Chaffee claims. Furthermore, most of the plant foods that I eat don’t have toxins in them, otherwise I wouldn’t be able to eat them.
Once we’ve established that a plant food is free of toxins or that we can eat it without being affected by the toxins, the next question to ask if: Do the plant foods meet our nutrition needs? And the answer is yes, as long as we eat a variety of them within a balanced diet.
Chaffee pointed out that most mushrooms / fungi are toxic, and he’s right. But fungi are technically not plants. They are a completely different taxonomical kingdom within the tree of life.
What is the exact source for the claim that Brussels sprouts have 130 toxins? I couldn’t find or identify it around 29:45.
I couldn’t find any information on the “Modern Toxin Theory of Disease” either. Maybe it’s a new theory, but in any case, it’s more likely that the research supporting the theory is meant to be provocative, not honest. Otherwise, the MTTD would be supported by the scientific consensus and would’ve been proposed decades ago. It didn’t take too long for people to figure out that cigarettes and tobacco are toxic and carcinogenic. Besides veganism (which isn’t mainstream), there’s no moral dogma to prevent the MTTD from becoming popular, so we can rule out the possibility that moral beliefs are suppressing the MTTD.
The sources cited at 29:45 are certainly cherry-picked. Anybody could cherry-pick sources to support whatever claim they want, hence consensuses and rationality are needed to determine the truth.
Chaffee claimed that vegetable oils are associated with increased cardiovascular risk, but that’s not true at all. Vegetable oils have unsaturated fat (the healthy type of fat that people should consume more of), and there’s no health risks to eating unsaturated fat. The scientific consensus does not support this claim. This is cholesterol denialism.
When Chaffee debated Dr. Matthew Nagra, Chaffee claimed that his video title “Plants Are Trying To Kill You” was an exaggeration and that he didn’t really believe that, but that’s not what he said in the video. I never expected quack doctors to make consistent claims anyway.

Chris MacAskil of Viva Longevity has also made a response video to Chaffee’s viral video.

5. Debunking More Claims Made By Anthony Chaffee

This section is a response to the Why We Are Carnivores Slide Presentation by Anthony Chaffee.

The real reason why human teeth shrunk is not because they ate meat that were softer than plants, but rather because humans evolved to cook their food before eating it. Thus, humans no longer needed teeth for breaking down so much of their food.
It’s possible that a decrease in nutrition may have caused height to decrease after the agricultural revolution, but we also have to keep in mind that humans in the past had to live by eating what they could hunt, gather, and find locally, thus there were no guarantees that humans could always get all the nutrition that they need.
- Another plausible explanation for the decrease in height during the agricultural revolution is that shorter heights made it easier to harvest grains and other crops, not poor nutrition.
- Conversely, it makes sense that a taller height could confer an evolutionary advantage for hunter and gatherers, and humans who had to fight frequent wars with other humans just to survive and protect themselves.
It’s more interesting how brain volume sizes went slightly down during the post agricultural revolution.
While brain sizes sharply went down when agricultural became the dominant source of food, it was a small drop in size, compared to the massive amount of brain growth that occurred during the Ice Age and prior.
- We should also keep in mind that intelligence isn’t advantageous in all environments. Maybe a slightly less intelligent brain was more adaptive for agriculture-dominant environments. If that’s necessary for survival in an environment that has reached its carrying capacity, then that’s okay.
One of the main reasons why the Masai are so tall and slender is because it makes it easy for their bodies to dissipate heat, especially when they live near the equator.
Being tall isn’t necessarily a good thing for health either, even if it’s associated with social prestige and desirability. To the contrary, shorter people live longer lives and have fewer diseases due to the square-cube law.
It’s important for humans to eat a sufficient amount of meat to be intelligent, but it’s a primary factor regarding intelligence in the modern world.
The American Indians had agriculture too. It’s not true that American Indians had completely carnivorous diets prior to Manifest Destiny.
- And even if they did have a heavily carnivorous diet, that doesn’t mean that they were smarter than the Europeans who visited them, like Chaffee had claimed. Maybe they were said to have a big heads, which are associated with bigger brains and thus higher intelligence, but if that’s true, then why are American Indians one of the least intelligent races today?
- A more plausible explanation for why Native Americans were among the tallest races in the world during the 1800s was because height probably gave them a competitive advantage in warfare.
It’s not true that the Maasai have a completely carnivorous diet.

6. The Bias In Claiming That Humans Evolved To Eat Meat

It was necessary for earlier humans and their descendants to consume more energy-dense meat, rather than plants, in order to go through the encephalization process.

That’s true. However:

All humans and all life on Earth will eat whatever they can find opportunistically.
See: The One Rule of Nature School Never Taught You - Casual Geographic.
Instead of pointing to specific examples for claiming that humans evolved to do this or that, we need to look at the entire picture. What the entire picture shows is that all life on Earth will eat whatever food it can opportunistically find and consume if it will increase their caloric and nutritional intake. A majority of humans and their ancestors ate plants for most of their evolutionary history.
The plants that we have today are not the same as what our ancestors had thousands of years ago. These days, humans have access to the hundreds and thousands of plants that grew around the world, and can GMOs. Technological changes like these make it possible to have a healthy plant-based diet with little to no meat, which is unlike the options that some of our ancestors had.
Even after most of the encephalization process occurred, most humans still ate plants for a majority of their diets. That is especially true in the Americas where the human hunter gathers had hunted, killed, and eaten all of the big game animals until they went extinct, thus leaving agriculture and food/cannibalism stolen from enemy tribes as their main source of food.
So, it makes sense that plants tend to be healthier than meat for humans when we consider that most of our human ancestors ate plants for most of their history.
When the predecessors to humans transitioned from gathering to hunting, hunting was a better way to increase caloric consumption then gathering plants.
- Agriculture later proved to be an even better way of increasing caloric consumption.
- However, it’s unlikely that humans could’ve done agriculture straight from the get-go, since agriculture requires a lot of intelligence for more efficient and effective gains.
- Agriculture probably would not have been possible if humans hadn’t hunted beforehand and undergone selection for higher intelligence.
If a proponent of the carnivore diet points to how hunting and eating meat caused the encephalization process, then I could just as easily point to how agriculture was necessary for humans to start forming civilizations. Agriculture became the more dominant and efficient method for getting sufficient calories and nutrition for survival and reproductive success. The Neolithic Revolution happened for a reason.

7. Longevity of Plant-Based Dieters versus Low-Carb Dieters

One of the main tradeoffs to minimizing the intake of carbohydrates is that it consistently leads to shorter lifespans.

By contrast, the average plant-based dieter lives a couple decades longer than the average carnivore does. Some vegans even managed to make it into their 90s or 100s. I found this surprising, but it may be doable as long as they take supplements.

For most people, I would endorse the advice made by Viva Longevity and Walter Willett. However, I also recognize that the healthiest diets depend on genetics to some extent (e.g. the Inuit are some of the only people in the world who are well-adapted to a completely carnivorous diet.) This is not medical, health, or dieting advice.