The Zero Carb “Carnivore” Diet: Healthy or Harmful?

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Woman Eating Pork Belly On a Fork.Over recent years, zero carb “carnivore diets” have rapidly grown in popularity.

There’s certainly no shortage of people claiming to enjoy the benefits of the zero carb lifestyle, and it even makes standard keto diets look carb-heavy.

But is a carnivore diet for humans healthy?

Is it ideal?

Or is it potentially dangerous?

This article takes a balanced look at the zero carb diet and the benefits, risks, and health impacts.

What is a Zero Carb Diet?

By its very nature, animal foods form the basis of the zero carb diet.

However, a zero carbohydrate diet plan can take several forms.

While some people concentrate on meat, others eat a wider variety of foods such as eggs, cheese, organ meats, and seafood.

The diet tends to be high in both fat and protein, and there are a wealth of success stories showing the important benefits the diet can have.

Specifically, zero carb dieters achieve significant results regarding weight loss, satiety, and better mental well-being.

On the other hand, there are many unknowns about the diet. In particular, potential long-term adverse effects are a concern for some.

Later on, this review will investigate both of these points in further detail.

Key Point: Zero carb diets completely restrict carbohydrate and focus on fats and protein. Many people believe they provide great health benefits, but others feel they are dangerous.

A 'no carb' sign - carb restriction.What Foods Have No Carbs?

Some people follow the “eat meat, drink water” mantra and eat nothing other than steak and water.

Others consume a greater variety of foods from various types of meat to bacon, organ meats, eggs, cheese, and coconut oil.

It’s worth noting that not all these foods are actually zero carb—eggs come in at 1g carbohydrate—but they are close enough.

Here is a list of (nearly) zero carbohydrate foods;

  • Bacon
  • Beef
  • Butter
  • Cheese
  • Chicken
  • Coconut oil
  • Duck
  • Eggs
  • Fish (mackerel, trout, salmon, and sardines for omega-3)
  • Ghee
  • Lamb
  • Lard
  • Olive oil
  • Organ meats (heart, kidney, liver)
  • Pork
  • Sausages
  • Shellfish
  • Turkey
  • Venison

While all these foods are “allowable” on zero carb, some Carnivore diet proponents eat very little other than beef.

Key Point: A no-carb diet menu can involve lots of different foods. These are predominantly foods from the animal kingdom, but plant-based fats are also possible.

Is There a Historical Argument For Zero Carb?

Picture of a caveman eating red meat or beef.

With the explosion of the ancestral health scene over the past decade or so, the foods our ancestors ate is an evergreen topic of discussion.

On that note, think back to the prehistoric days and a caveman tucking into a slab of meat is a typical image.

And it’s accurate imagery too; as a species, humans have been eating meat for tens of thousands of years.

Despite vegan activist groups vehemently protesting this, there is a wealth of evidence to support ancient people being meat eaters (1, 2, 3, 4, 5).

An interesting hypothesis worth reading is ‘The Carnivore Connection,’ which views carnivory as essential to recent human evolution.

In particular, the authors believe that (6);

  • Low carbohydrate, high protein diets dominated the previous two million years of evolution.
  • For a large amount of this time, dietary carbohydrate was scarce due to successive ice ages.
  • Insulin resistance genes developed to give a survival advantage in response to lengthy low-carbohydrate periods.
Key Point: Humans and our ancestors have been deriving energy from animal foods for millions of years. It’s likely that some societies will have been zero carb for significant periods during this time.

But…Ancient Humans Ate Plant Food

Hunter-gatherers often lived through times of famine, and they ate what they could to survive.

Would they pass up some juicy berries they came across? Not likely.

Also, much of our modern evolution reportedly took place in Africa, a region with thousands of different species of vegetation.

Outside of the ice age periods, there would have been sufficient plant food available.

It’s highly unlikely people would pass this up, especially during times of hunger.

As a large source of energy, it’s certainly likely that ancient man valued meat more than plant foods.

However, this doesn’t mean plant foods played no part in the diet. Further, the majority of evidence indicates humans are natural omnivores and had different diets depending on their location and environment (7, 8, 9, 10).

Key Point: When we theorize on our ancient history, it’s hard to provide a 100% accurate portrayal of life. However, it’s highly likely that most humans ate plant food when available.

Is Restricting Vegetables Dangerous?

Broccoli and Other Vegetables With Evil-Looking Broccoli Shadow.

A zero carb diet obviously involves cutting out vegetables.

Vegetables (especially greens) are very high in nutrient density, and the media constantly bombard us with messages about their health properties.

As a result, the majority of the health-conscious population would probably react in horror to the idea of restricting them.

But are vegetables really so necessary?

Vitamins and Minerals

First of all, we have to forget the myth that vitamins and minerals only come from plant foods.

They do not.

In fact, animal foods are some of the most nutrient-dense in the world.

For example, here are the nutritional profiles of apples, eggs, kale, and liver (11, 12, 13, 14).

To make it fair, the value is the RDA % per 100g;

NutrientAppleEggKaleLiver
Vitamin A1%10%272%634%
Vitamin C8%0%68%3%
Vitamin D0%8%0%Low
Vitamin E1%5%4%3%
Vitamin K3%0%1021%4%
Thiamin1%4%4%13%
Riboflavin2%24%4%201%
Niacin0%0%2%88%
Vitamin B62%6%7%51%
Folate1%9%3%63%
Vitamin B120%21%0%1176%
Pantothenic acid1%14%0%71%
Calcium1%5%7%1%
Iron1%10%5%36%
Magnesium1%3%5%5%
Phosphorus1%19%3%50%
Potassium3%4%7%10%
Sodium0%12%1%3%
Zinc0%7%2%35%
Copper1%5%8%714%
Manganese2%2%21%18%
Selenium0%45%1%18%

As shown above, both animal foods and plant foods can contain high amounts of vitamins and minerals. Organ meats are especially nutritious.

Many people presume that zero carb diets are going to be severely deficient in many nutrients.

However, it is certainly possible to get most essential nutrients from eating a range of meat, seafood, eggs and organ meats.

On the other hand, antioxidant vitamins C and E are particularly difficult to obtain from animal foods.

Key Point: Animal foods are just as nutritious as plant foods are – if not more so. It is possible to get most essential nutrients from a varied zero carb diet.

Are Nutrient Deficiencies Important?

Many zero carb proponents point to accounts of people eating a meat-only diet for 15-20 years with no evidence of harm.

In addition, our biological need for certain nutrients drops as our carbohydrate intake lowers.

For example, we don’t require the numerous vitamins involved in energy (carbohydrate) metabolism when we are consuming no carbs (15, 16, 17).

Despite this, we should remember that while anecdotes are always valuable and relevant, they are not evidence.

We can’t prove the long-term safety of zero carb simply because we don’t have sufficient research.

Also, chronic health problems typically develop over decades, so we can’t assume that 15-20 years of feeling great is predictive of the future.

This does not mean that a zero carb diet can’t be healthy in the long-run. It could well be, but it’s the responsible position to take since we don’t have much evidence now.

Key Point: Low intake of certain nutrients may not be as important on a zero carb diet.

Polyphenols

Picture of a raspberry attached to a stem.Polyphenols are biologically active compounds naturally found in plants, and particularly good sources include cacao, berries, olives and red wine.

These polyphenols have health-protective properties, and evidence from randomized, controlled trials (RCTs) shows that they help fight oxidative stress and aging-related illness (18, 19, 20).

Notably, numerous studies—including RCTs—show that consuming polyphenols alongside meals;

  • Prevents biological processes in the stomach that lead to LDL oxidation (21, 22).
  • Creates oxidized-LDL antibodies (OLABs) in response to the presence of oxidized LDL (2324).
  • Polyphenols from tea, herbs, and red wine can inhibit the formation of heterocyclic amines (HACs). These compounds are “likely carcinogens” and can occur when cooking meat at high temperatures or to a well-done stage (25, 26, 27).
Key Point: A wide body of evidence shows the health benefits of polyphenols. Zero carb diets don’t include food sources of these compounds, although some people consume olive oil and red wine.

What Are the Health Benefits of Zero Carb Diets?

As with any diet, there are several pros and cons of a carnivorous diet.

Firstly, zero carb diets have a range of health benefits.

In general, these are somewhat similar to the carbohydrate-restriction benefits of a ketogenic diet.

However, the effects are likely more powerful due to the further restriction of dietary carbs.

A typical zero carb diet should result in;

  • More efficient weight loss: most people experience significant weight loss results; a reduced body fat percentage and losing weight around the waist is common. Additionally, carbohydrate restriction has a superior impact on weight loss and metabolic syndrome risk than low-fat diets do (28, 29, 30).
  • Better mental wellbeing: very low carb diets tend to result in better cognitive performance, improved mood, focus, and mental clarity (31, 32). 
  • Reduction in food cravings: ultra-low carb diets massively improve satiety and reduce food cravings (33, 34).
  • Decreased triglycerides, higher HDL: higher levels of dietary fat and lower levels of carbohydrate reliably increase HDL and reduce triglyceride levels (35, 36).
  • Reduced blood glucose: restricting carbohydrate reduces and stabilizes fasting blood sugar levels (37).
  • Less digestive issues: reducing carbohydrate tends to improve gas, bloating problems and heartburn. On this note, many people turn to the zero carb diet after unsuccessfully trying to resolve sometimes severe digestive issues.

The Bacon Experiment

Crispy Slices of Streaky Bacon.

Okay, we shouldn’t take this as evidence, but there was an interesting trial undertaken by one man.

What he did was…eat bacon.

For 30 days. Nothing else – just bacon!

The results?

  • 20 pounds of weight loss
  • Improved cardiovascular health markers
  • Lower blood pressure

These results don’t prove or verify anything—and it’s not a diet I’d recommend—but it does upset the conventional fear of meat as some kind of “artery-clogging” food.

In fact, study after study shows that meat consumption and animal fat increases HDL and reduces triglycerides (35, 36, 37).

For those unaware, these health markers are likely the most protective against cardiovascular risk (38).

Key Point: Ultra-low carb diets tend to improve health markers such as blood sugar and triglycerides. Additionally, they are great for satiety and managing food cravings.

Are There Any Health Risks?

There don’t appear to be any immediate health risks from zero carb diets, other than typical keto flu style symptoms.

In my personal opinion, there’s no reason to suspect that zero carb dieters can’t enjoy long-term health.

However, there is also no evidence of long-term safety.

Is it Sustainable?

One of the biggest problems with all diets—whether vegan, paleo, keto or zero carb—is sustaining them.

Pizza delivery with friends? Well, that’s a difficult ask even for a strict paleo dieter.

This lifestyle struggle only multiples with zero carb, since the diet rules out almost all non-animal foods.

Eating no carbs at all certainly has an effect on social events.

For instance, occasions like birthdays, Christmas dinner, or a night out with friends or family become much tougher.

Do-able, certainly – but tougher.

On the positive side, zero carb foods such as bacon and beef are delicious and make the limited food choice easier.

And many people are sustaining the diet – both because they love the food and feel it is making them healthier.

Key Point: Sticking to a zero carb diet will be difficult for some due to social occasions.

Zero Carb: Healthy or Harmful?

Personally, I think that a zero carb diet is much healthier than the ultra-processed foods typical of standard Western diets.

I also believe that the diet is unlikely to be harmful – especially if well-formulated.

However, there is so much evidence for the health benefits of foods like cacao, berries, avocados, olives, and various other fruit and vegetables.

Sure, it might be possible to find a study or two about anti-nutrients in these foods, but the body of evidence points to them having substantial health benefits.

To sum up, I don’t think a zero carb diet is harmful.

But personally, I think a diet that includes a variety of nutrient-dense animal and plant foods is optimal.

For a closer look at two slightly higher carb diets, see this guide to keto vs paleo.

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C.J.
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C.J.

You forgot to include cancer risks. What about those?

Murray Duffin
Guest

You have not considered effects on the gut microbiome. It seems likely that the loss of healthy fiber is deleterious to gut health, especially the mucosal lining of the large intestine. Several recent papers address this issue, but there are none to investigate if protein eating microbes might also thrive and keep a healthy gut. That result seems very unlikely however.

Leo
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Leo

Please revise your sentence above regarding the sustainability of diets. Veganism is not a diet – it’s a lifestyle based on compassion for all beings, including our own personal health and our planet. When you have these points in mind it’s not hard to maintain this lifestyle. If you want to simply compare diet, you can replace vegan with plant-based diet which is a diet many follow simply for health benefits, like others do with many other diets. Thank you

Richard Howes
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Richard Howes

I’ve been keto for 6 months with great results, and have switched to carnivore for the last week. I intend to give it a shot for about 2 months and see. I do eat mushrooms, however, and am interested in your comments as to their effect.

Richard
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Richard

Excellent Article. Presented in a very factual manner.

Rhonda
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Rhonda

For 5 years I struggled with weight gain. I craved sugar and although I ate a well balanced diet, my sugar craving meant I was never satisfied. My teen daughter suggested I eat a zero carb diet and this is the result. I lost 10 pounds in 48 hours, two weeks later I was down 20 pounds and in 5 months, lost a total of 50 pounds. I was athletic before the weight gain and was able to retain muscle. There was no skin sagging, I was never hungry…very important, and I had a lot of energy. Socializing wasn’t a… Read more »

Inama Diebo
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Inama Diebo

Michel Joseph, MS.

Very well written article. I’m curious what diet you are currently following, and what you have done in the past which led you to where you are today.

I’m currrently following modern day paleo, which includes gluten free grains and soaked legumes, but no dairy. I have increased veggie consumption a lot since going paleo in early 2015, but I’m thinking my digestive system needs a break from plant foods. Also, I am wondering about lower plant foods might improve my chronic acne symptoms.

Thanks again!

Craig
Guest

As those more experienced than I have pointed out – meat digests in about 1 hour in bile, (unlike plants which require bacteria). Meat eaters do not require so much anti oxidants simply because we do not create such a highly oxidative environment. Not needing to create so much mineral demanding molecules, such as glutathione makes us more tolerant to environments that are depleted in minerals, like selenium for instance. For reasons like this the RDA’s do not seam to be relevant to those on long term ZC. Really well written and researched – thank you!

Sushil kumar
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Sushil kumar

Thanks Micheal The issue of insulin resistance is more to do with consumption of meat products..,nothing to do with low carb diet..So for diabetic patients currently to reverse diabetes doctors recommend to abstain from meat and migrate to plant protein and stay at 25% carb intake. Infact they strongly suggest to avoid fish and limit protein to lean chicken. India and USA has large population of diabetics. Indians eat large amounts of carbs and Americans eat large amounts of meat along with high glycemic sugary food and animal and dairy fat . Also human beings by design have a long… Read more »

Sushil kumar
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Sushil kumar

Animal foods take long time to digest and also chances food getting putrid during long journey from oesophagus to small intestine.. it takes anything between 24 to 48 hrs for animal food to digest. However vegetarian food may take 12-24 hrs to clear through all intestines & light on stomach.While animal food doesn’t increase blood sugar level , it would increase insulin resistance and whereas carbs like
Potatoes and rice would elevate the blood sugar level. Fibre in plant food would aid in colon cleansing. My view is that we should restrict carb intake to 25% of total food intake

John H
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John H

Nicely balanced article. The only additions I could suggest would be a comment on fiber and possible digestion issues. Also the high levels of protein and mTor pathway activation. They could be the chronic problems down the road, however, we won’t really know until someone studies it with high N values.

Stefhan Gordon
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Stefhan Gordon

Not to nitpick, but all that “vitamin A’ in kale is beta carotene, a precursor, not preformed retinol. So if you’re lacking or deficient in the enzyme dioxygenase, you’re not going to utilize that “vitamin A” especially if you’re on a low fat diet. Also with the vitamin K, you really have to break that down into K1 and K2 since kale is a good source of the former while grass fed beef liver is a good source of the latter. Kale doesn’t have any K2.