If you have at all fallen victim to the propaganda that eating meat is a dangerous to our health and environment, than what you have heard so far is likely a bit shocking.  You may be wondering, “is consuming a meat based diet actually safe?” A common way this question is asked is, “how many studies have shown that long term carnivore dieting in humans is healthy?”  The answer is just as many studies as there are studies showing that it is harmful to health, 0. We can thank our old friend Ancel Keys for this.

Ancel Keys, a researcher in the 70s, had a vendetta against dietary fat and decided to cherry pick data from his studies to show that fat was the cause of heart disease.  It was just fat that Keys threw under the bus, particularly saturated fat. This eventually led to the belief that meat is dangerous and became the reason why the American Heart Association recommended a low-fat diet for such a long time. If you want to learn more about how we were duped by Ancel Keys and how that led to the many misconceptions many still have about nutrition today, I highly recommend reading The Big Fat Surprise by Nina Teicholz.

Regardless, the truth is there is limited research looking at the use of a carnivore diet in humans, especially long term.  But there is some data that we can look at to begin to understand whether or not this diet is safe. Like a study published in the 1920’s where two men followed a meat only diet for a year (1).   Here were the findings from that study:

While this old study does demonstrate that these two particular men did not die from following an all meat diet for a year, it is still not enough evidence to definitively say that a carnivore diet is safe.  However, we also have anecdotal evidence through the stories of the Inuit who ate primarily animal fat and experienced little to no health issues. Still, this is not research of the highest confidence which is why many still question the safety of the diet.  However, most of the concerns about the safety of the diet are general keto concerns that are easily addressed.  Here are some of the most common concerns with both all-meat and ketogenic diets:

Digestive Health

One of the first concerns regarding an all meat diet is digestive health.  After all, getting enough fiber in your diet is essential to good health right?  Not so fast. Like many plant based diet studies that demonstrate improvements in health, much of the research supporting the need for dietary fiber is studies of people switching from a Standard American Diet to a diet richer in fiber.  If you are consuming a diet rich in processed carbohydrates and you switch to food sources that contain more fiber, of course you are going to get healthier. You traded McDonald’s for broccoli, but that doesn’t mean you need the fiber to be healthy.

Our understanding of fiber is changing, especially with more research coming out demonstrating that in many cases, fiber does more harm than good.  Like that 2012 study that found that patients suffering from constipation actually saw improvements in their symptoms when they completely removed fiber (2).  In fact, for the subjects who completely cut out fiber, their bowel frequency increased from one nearly every four days to one every day! Those who continued eating fiber continued to have one bowel movement every almost seven days on average. These results allow us to debunk the fact that you need fiber to have healthy bowel movements.

Another proposed benefit of fiber is that it can be converted to butyrate which helps maintain gut health and the integrity of our intestinal lining.  Interestingly, it has actually been shown that the amino acid lysine, which is found in meat, can also be converted to butyrate and offer intestinal protection (3).  Meat saves the day again.

When it comes to digestive health, the only legitimate point against the safety of a carnivore diet I have heard was from Dr. Rhonda Patrick on an episode of the Joe Rogan Experience.  Dr. Patrick mentioned that amino acid fermenting bacteria, which would be present in the gut of those eating a lot of meat, can release toxins that could be harmful, but the compounds released by fiber fermenting bacteria could actually combat toxins from the amino acid fermenting bacteria.  Now obviously this has only been tested in cell culture studies and is hard to replicate in a human model, but is something that we need a lot more research on.

CVD Risk:

Fat, as many should know by now, does not pose the same health risk that we once thought it did.  If you know this, it is thanks to the debunking of that cherry picked data from Ancel Keys mentioned earlier.  His work continues to shape our dietary guidelines and ruin the health of millions.

Remember, it wasn’t just fat that Keys demonized, it was animal fat and particularly saturated fat, both of which have been hotly debated over the last few decades with many proponents of high fat dieting still not sure where to stand on saturated fat.

Why the confusion?  There are some very poor studies out there that have fooled many people.  Like this study that reported that that saturated fat intake was associated with a greater risk of cardiovascular disease or CVD (4).

The problem with this study, and many other studies like this that are used to support the belief that fat and meat are dangerous, is that they are weak studies that only demonstrate correlation and not causation.

In studies like these, individuals are selected and analyzed for cardiovascular disease risk.  They are then questioned on their diets. The answers to these questions are used to formulate the conclusion of the studies.  If many people with high CVD risk answer that they are eating hamburgers, it is assumed that fat, especially saturated fat is the cause of this increased risk in CVD.

We cannot assume that because someone diagnosed with heart disease is eating a lot of saturated fat that fat is the cause of the disease.  Especially if the subjects were not even asked if they were also eating carbohydrates. Hint, Hint. What about the bun on that hamburger?

Interestingly, in that same study, it was found that saturated fats from pastries and processed foods were associated with an even higher risk of CVD which demonstrates carbohydrates and sugars contributing to the damage.  Many anti-meat proponents would skim by these results.

While it was great that this study looked at sugar and processed carbs, it failed to look at how many total carbs the subjects with the highest saturated fat intake were also eating. Knowing the trends of human nutrition, I would venture to say this information would have produced significantly different findings.

Regardless, studies like this get misconstrued and turned into blog posts with titles like, “Saturated Fat Increases the Risk of Cardiovascular Disease” which wrongfully scares people away from fat and meat.

The take home message here is that epidemiological nutrition studies are weak and do not shed enough light on the true cause of an outcome.  Even if they did, a review of all of these such studies actually tells us that saturated fat is not as scary as some of these single papers are making it.  Several reviews of the research have actually found no associated between saturated fat intake and all-cause mortality, coronary heart disease or mortality, ischemic stroke, or type 2 diabetes in healthy adults (5,6).

You may be wondering, “what about cholesterol?”  Same thing. Research on cholesterol has also been misconstrued and falsely used to support the thought that cholesterol contributes to heart disease.  A basic understanding of physiology tells us that it is high cholesterol in conjunction with elevated inflammation and damaged arterial lining (the glycocalyx) that allows cholesterol to product damage.  Elevated inflammation and damaged arterial lining occurs when we eat a lot of carbohydrates, especially processed carbohydrates.

In summary, fat, cholesterol, and meat independent of carbohydrates is great for us and is not something we should fear.  In fact, there have been numerous studies that have demonstrated that a low carb, high fat diet can improve many cardiovascular risk factors (7, 8, 9, 10).

Cancer:

Then of course, cancer is a big combating argument against an all meat diet.  Similar to CVD, research showing that high fat and meat based diets causes cancer are also weak epidemiological studies that we cannot rely on for causation.

If you want to learn more about all of the bogus information out about meat and cancer, learn from the expert, Dr. Georgia Ede by checking out her article WHO says Meat Causes Cancer.

Kidney Damage:

The high protein nature of the carnivore diet also leads to assume that it is dangerous to your kidneys.  This is also a myth.

The reason many people think that protein could cause kidney damage is from increasing glomerular pressure and hyperfiltration.  However, research has found no significant evidence for any harmful effect of high protein consumption on renal (kidney) function in individuals with healthy kidneys (11).

Notice that said for healthy individuals.  For those suffering from kidney disease, there may be value to restricting protein but the evidence is unclear.  Regardless, it should be noted that research has already found that a ketogenic diet may be beneficial for managing diabetic nephropathy (12)

Environmental Impact

It is not just health concerns that prevents many people from eating meat.  The environmental impact of meat is also a common concern among many. However, this is also a common misconception.

A common statistic that is often used to accuse cattle farming as being environmentally unfriendly comes from the UN Food and Agriculture Association which has previously claimed that cows produce more greenhouse gases than all of the world’s transportation combined, 18%.  However, it has since come out that the numbers in this report have been skewed based on biased calculations. In fact, one author from the report has since said that these were “unfair” comparisons and that cows contribute less than 3% of greenhouse gases.

The truth is that if farming practices are done correctly, cows can actually be beneficial to the environment.  In fact, research has found that grazing cows can help remove carbon from our atmosphere (13) and reduce the natural emissions of nitrous oxide from the land (14).  If you breakdown the numbers, these abilities of cows allow them to be considered “carbon negative” if they are fed and housed correctly.

Water use by these cows is another common concern for the environmental impact of red meat.  Again, this is another common misconception. If cows are fed the way they should be, grazing on the land, then water use is not a problem.  It is feed production that requires the most water use when it comes to raising cattle. Regardless, many of the statistics that look at water use from cattle farming fail to decipher the difference between natural rainfall and irrigation which estimates the water use of these cattle to be very high and does not give a full picture of the truth.  Research that has looked at the water use of non feedlot animals has found that the amount of non-rainfall water used by cattle is more like 18-214L/kg of meat, a substantially lower number than what has previously been estimated.

The key theme here is the importance of how the animals are farmed.  Yes, feedlots do not leave the best environmental footprint but cows that are grazing on the land, what we like to call “grass-fed”, are not just better for our health but also better for the environment.

Based on the information available, I believe that a carnivore diet is safe and effective and is a tool that I use frequently when looking to achieve a particular goal. While I do think the diet is relatively safe, that does not mean that I don’t think there are some potential “dangers” to consider.

Potential Dangers of Carnivore

Most of the worries about carnivore being unsafe are not justified or supported by research.  However, there are some concerns that I believe you should be aware of.

Any of these “negatives” of carnivore should not prevent you from following the diet.  They are meant to provide an expectation for some lifestyle drawbacks you may experience on the diet and ways to optimize your diet to reduce any possible negative effects.  The food we eat is supposed to fuel our health and carnivore does.

Eating Disorders

Depending which version of Carnivore you follow, the diet can be very restrictive.  Even the simpler, animal product only version of carnivore that allows for dairy and eggs can feel restrictive to many.

Individuals who are prone to poor food relationships and eating disorders, may find it better to first start with a ketogenic diet before jumping into an even more restricted carnivore diet to avoid letting bad food habits spiral out of control.

Lifestyle Component

Another possible negative to the carnivore diet is that it is a little boring.  It’s easy to get burnt out on eating the same foods all the time or just having meat.

Personally, as someone who is a big fan of carnivore, I have still found that dining out on carnivore isn’t very fun unless you have great barbeque or steak joints around you.

Non-Carnivore Food Intolerance

In Jordan Peterson’s episode on the Joe Rogan Experience, he mentioned that after following carnivore for a while, anytime he ate a non-carnivore meal he felt pretty horrible.

While I speculate that this is a lot more common for someone who is suffering from auto-immunity, like Jordan and his Mikaela, you may find that if you want to come off of carnivore, you need to do so slowly and with the right foods to avoid any discomfort.

How You Cook Your Food

How you cook your food is also important. Frying meat at high temperatures can be carcinogenic and should be avoided.  However, it is important to point out that the aromatic carcinogens that can come from high heat cooking is not just specific to red meat but also fish and poultry.  Meat is not meant to be fried in a pan with oil. Choose better methods like grilling!

Food Quality/Source

I believe it’s also important to consider the sourcing of your food.  I know not everyone wants to admit it, but there is a big difference between a grass-fed steak and a bunless burger from McDonald’s cooked in vegetable oil.

Supporting the importance of food quality is not the most popular camp to be in.  Besides being more expensive, many people do not feel that consuming low quality foods is actually dangerous.  I disagree.

A recent review demonstrated that grass fed cattle have a greater proportion of conjugated linoleic acid (CLA) and omega 3 fatty acids on a gram per gram basis (15). CLA has been associated with improving insulin sensitivity and may aid in muscle maintenance and weight loss. Omega 3's on the other hand play a variety of important roles throughout the body including cell membrane development, neuronal development and reducing inflammation. Additionally, these researchers also found that grass fed cattle had elevated precursors for vitamin A, E and the potent antioxidant glutathione compared to grain fed.

I believe that the best way to follow any diet, especially a carnivore diet, is to focus on the quality of your food to ensure that you are optimizing your micronutrient intake, but also preventing your body from taking in additional toxins that are not necessary.

It is also worth mentioning that grass-fed animals tend to come from farms practicing those farming techniques that are superior to the environment that we mentioned earlier.

Conclusion

While we do need a lot more research on the carnivore diet in humans, the research we do have available as well as the many anecdotal stories tells us that the carnivore diet is not only safe, but extremely beneficial for improving our health. As always, experiment for yourself. Give the diet and try and see how your body responds!

REFERENCES

1. McClellan, W. S., & Du Bois, E. F. (1930). Clinical calorimetry XLV. Prolonged meat diets with a study of kidney function and ketosis. Journal of Biological Chemistry, 87(3), 651-668.
2. Ho, K. S., Tan, C. Y. M., Daud, M. A. M., & Seow-Choen, F. (2012). Stopping or reducing dietary fiber intake reduces constipation and its associated symptoms. World Journal of Gastroenterology: WJG, 18(33), 4593.
3. Bui, T. P. N., Ritari, J., Boeren, S., De Waard, P., Plugge, C. M., & De Vos, W. M. (2015). Production of butyrate from lysine and the Amadori product fructoselysine by a human gut commensal. Nature communications, 6, 10062.
4. "Dietary fat intake and risk of cardiovascular disease and all-cause mortality in a population at high risk of cardiovascular disease." The American journal of clinical nutrition 102, no. 6 (2015): 1563-1573.
5. De Souza, R. J., Mente, A., Maroleanu, A., Cozma, A. I., Ha, V., Kishibe, T., ... & Anand, S. S. (2015). Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. Bmj, 351, h3978.
6. Malhotra, A., Redberg, R. F., & Meier, P. (2017). Saturated fat does not clog the arteries: coronary heart disease is a chronic inflammatory condition, the risk of which can be effectively reduced from healthy lifestyle interventions.
7. Dashti, H. M., Bo-Abbas, Y. Y., Asfar, S. K., Mathew, T. C., Hussein, T., Behbahani, A., ... & Al-Zaid, N. S. (2003). Ketogenic diet modifies the risk factors of heart disease in obese patients. Nutrition, 19(10), 901.
8. Brehm, B. J., Seeley, R. J., Daniels, S. R., & D’Alessio, D. A. (2003). A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women. The Journal of Clinical Endocrinology & Metabolism, 88(4), 1617-1623.
9. Volek, J. S., Phinney, S. D., Forsythe, C. E., Quann, E. E., Wood, R. J., Puglisi, M. J., ... & Feinman, R. D. (2009). Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids, 44(4), 297-309.
10. Sharman, M. J., Kraemer, W. J., Love, D. M., Avery, N. G., Gómez, A. L., Scheett, T. P., & Volek, J. S. (2002). A ketogenic diet favorably affects serum biomarkers for cardiovascular disease in normal-weight men. The Journal of nutrition, 132(7), 1879-1885.
11. Devries, Michaela C., Arjun Sithamparapillai, K. Scott Brimble, Laura Banfield, Robert W. Morton, and Stuart M. Phillips. "Changes in kidney function do not differ between healthy adults consuming higher-compared with lower-or normal-protein diets: a systematic review and meta-analysis." The Journal of nutrition 148, no. 11 (2018): 1760- 1775.
12. Poplawski, Michal M., Jason W. Mastaitis, Fumiko Isoda, Fabrizio Grosjean, Feng Zheng, and Charles V. Mobbs. "Reversal of diabetic nephropathy by a ketogenic diet." PloS one 6, no. 4 (2011): e18604.
13. Pelletier, N., Pirog, R., & Rasmussen, R. (2010). Comparative life cycle environmental impacts of three beef production strategies in the Upper Midwestern United States. Agricultural Systems, 103(6), 380-389.
14. Wolf, B., Zheng, X., Brüggemann, N., Chen, W., Dannenmann, M., Han, X., ... & Butterbach-Bahl, K. (2010). Grazing-induced reduction of natural nitrous oxide release from continental steppe. Nature, 464(7290), 881.
15. Daley, C. A., Abbott, A., Doyle, P. S., Nader, G. A., & Larson, S. (2010). A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef. Nutrition journal, 9(1), 10.