What is the 'carnivore diet' and is it a bad idea?

A standard breakfast on the carnivore diet might be eggs and bacon without toast or sides. Pexels/freestocksorg, CC BY^[1]

Are there any nutritional benefits?

The short answer is no.

It may be theoretically possible to get all essential vitamins and mineral from animal products. For example, lean red meat^[2] is a good source of iron, zinc and vitamin B12, while oily fish is a good source of essential fatty acids, such as omega-3s.

But unless your diet is very well planned, eating only animal meat could lead to insufficient intake of certain vitamins and minerals. This is especially the case with vitamin C and folate, where the main food sources are fruits^[3], vegetables and wholegrains.

Importantly, dietary fibre is noticeably absent from a carnivore diet. This is a problem because a low-fibre diet^[4] can increase your risk of diabetes, heart disease and some cancers.

To avoid any dietary deficiencies, the Australian Guide to Healthy Eating^[5] recommends eating from the five core food groups: fruits, vegetables, cereals, lean meats and dairy.

Read more: What's this 'longevity' diet, and will it really make you live longer?^[6]

Is it bad for your health?

Most likely.

Most evidence for benefits of this diet is anecdotal – based on personal experiences, rather than scientific evidence.

A recent article^[7] identified self-reported health benefits and high satisfaction among adults who followed a carnivore diet for six months or more. However, since the study involved asking people how much they liked a diet they had chosen to put themselves on, we can’t conclude much from its findings.

When it comes to high protein diets in general, we know the amount and quality of protein matters.

Research^[8] tells us sustaining a high protein diet over a long period of time (six months or more) could impair the ability of our liver, intestine and kidneys to detoxify ammonia, which is the waste product made by our body during the digestion of protein.

For example, a 12-month randomised controlled trial^[9] looked at how protein affects kidney function. Researchers prescribed adults to either an Atkins diet (30% of total energy intake from protein) or a control diet (15% of total energy intake from protein, which is close to the typical Australian diet^[10]).

The trial reported a rise in clearance of creatinine (a product of protein digestion) in adults on the Atkins diet at 12 months, but not 24 months. This could suggest that after a time, the kidneys became less able to clear away potentially harmful byproducts of excess protein, leading to kidney injury^[11].

The only study on the carnivore diet was a self-reported survey of people who had chosen to go on the diet. Emerson vieira/Unsplash, CC BY^[12]

However, because of the limited food selection, high cost of meat, repetitive nature of many high protein diets, and concerns over whether it would be ethical, there aren’t many long-term trials.

That said, evidence from large and long-term observational studies tells us diets high in red meat and processed meats increase our risk of heart disease^[13] and many cancers^[14].

While one person may be able to sustain a carnivore diet for months, or even years, without any health complications, that’s certainly not going to be the case for everyone.

Read more: What are 'fasting' diets and do they help you lose weight?^[15]

How much meat is too much?

For an adult, a high-protein diet^[16] is generally defined as consuming 2 grams or more of protein per kilogram of body weight per day.

So for an 80kg male, this would be 160g of protein per day. And what does 160g of protein in whole foods look like? It’s about equivalent to six medium lamb chops a day (550g of meat^[17]).

The Conversation, CC BY-ND^[18] When we compare this with national guidelines, the Australian Dietary Guidelines^[19] recommend the average adult eats a maximum of 455g of cooked lean red meat per week (or 65g a day, equivalent to one small lamb chop). For heart health specifically, the Heart Foundation^[20] recommends eating less than 350g of cooked unprocessed red meat per week (50g a day). So what’s the verdict? The strongest evidence^[21] shows eating a diet rich in whole plant foods, such as fruit and vegetables, with a moderate amount of lean and unprocessed red meat, poultry and fish is good for our health^[22]. For this reason, the Mediterranean diet^[23] has become ubiquitous with a healthy diet. If you are considering trying a high-protein diet, it’s recommended to first consult a health professional, such as an accredited practising dietitian^[24]. References^{^} CC BY (creativecommons.org)^{^} lean red meat (www.eatforhealth.gov.au)^{^} fruits (www.eatforhealth.gov.au)^{^} low-fibre diet (www.ncbi.nlm.nih.gov)^{^} Australian Guide to Healthy Eating (www.eatforhealth.gov.au)^{^} What's this 'longevity' diet, and will it really make you live longer? (theconversation.com)^{^} article (pubmed.ncbi.nlm.nih.gov)^{^} Research (pubs.rsc.org)^{^} randomised controlled trial (cjasn.asnjournals.org)^{^} typical Australian diet (www.abs.gov.au)^{^} kidney injury (jasn.asnjournals.org)^{^} CC BY (creativecommons.org)^{^} heart disease (pubmed.ncbi.nlm.nih.gov)^{^} cancers (www.wcrf.org)^{^} What are 'fasting' diets and do they help you lose weight? (theconversation.com)^{^} high-protein diet (jasn.asnjournals.org)^{^} 550g of meat (www.foodstandards.gov.au)^{^} CC BY-ND (creativecommons.org)^{^} Australian Dietary Guidelines (www.eatforhealth.gov.au)^{^} Heart Foundation (www.heartfoundation.org.au)^{^} strongest evidence (www.thelancet.com)^{^} good for our health (www.eatforhealth.gov.au)^{^} Mediterranean diet (onlinelibrary.wiley.com)^{^} accredited practising dietitian (member.dietitiansaustralia.org.au)

Read more https://theconversation.com/what-is-the-carnivore-diet-and-is-it-a-bad-idea-189464

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