Ex-vegan turned carnivore Isabella Ma, better known to her nearly half a million followers on Instagram as @steakandbuttergal, has glowing skin and a flat stomach. She looks directly at the camera as she chomps down on an entire stick of butter. It’s part of her “high fat carnivore diet” to which she attributes a whole host of health benefits, not least of which is the claim she “literally never fart[s] any more” and has a single “scentless” bowel movement a week.

A lot of gym bros also back the diet touted for helping people lose weight and build muscle, such as Antonio Angotti, who says the fat in red meat “includes almost every nutrient humans need to thrive” and invokes religion as part of his dietary choices, saying he eats “just foods God will actually bless”. It’s also been platformed by Joe Rogan and Jordan Peterson.

But what do the experts have to say about one of the most viral health trends of the moment?

What is the carnivore diet?

It’s an all-meat or predominantly meat diet, often incorporating other animal-based products including eggs and dairy products – but very little or no plants or carbohydrates. Some people adhere to it by eating solely animal-based products, while others have variations that might include some fruits or vegetables.

What do the experts think of it?

There are two issues when it comes to diets relying on meat – what you’re missing out on, as well as the risk of what you could be consuming too much of, says Dr Eden Barrett, a public health nutrition researcher and dietitian at the George Institute for Global Health.

The chance of deficiencies in essential vitamins and minerals, including vitamin C and folate, is really high. You’re also virtually eating no fibre, a nutrient that evidence shows is protective against heart disease, certain cancers and a lot of chronic diseases, as well as crucial for digestive health, Barrett says. You could also be missing out on the variety of bioactive compounds in food, such as antioxidants. Those aren’t essential nutrients – we don’t need them to survive – but they can help us live longer.

There is also the risk of consuming too much animal meat. This can be high in saturated fat, which tends to raise levels of bad cholesterol – a known risk factor for heart disease, she says. Red meat and processed meat has also been shown to be associated with risk of cancers, while consuming too much protein can also put kidney function at risk, Barrett says.

There isn’t a lot of scientific evidence for what the long-term effects of a carnivore diet are, as opposed to the benefits of a balanced diet of fruits, vegetables, meat and meat alternatives, dairy, nuts and legumes on a daily basis, which is based on “years and years of accumulated evidence”, Barrett says.

But what about all the people who say it has helped them?

“People say they feel better when they’re on the carnivore diet, and that’s not something that we should dismiss,” Dr Emma Beckett, an adjunct senior lecturer in nutrition at the University of New South Wales, says. They commonly mention less brain fog, more energy, improved sleep and better skin health.

“But feeling better is only part of health, and we can’t feel things like our arteries getting clogged and … our blood pressure going up, so just feeling better doesn’t mean you’re necessarily doing yourself any favours in the long term,” Beckett says.

UK-based nutritionist Dr Richie Kirwan has called the carnivore diet the world’s most hectic elimination diet – a kind of diet used in medicine to figure out which foods people are having adverse reactions to. “That explains why people feel better on it, because if you’re responding negatively to a food, cutting it out will make you feel better,” Beckett says.

But with elimination diets, foods are gradually reintroduced – which is not happening with the carnivore diet. Instead, people continue eating a low-diversity diet.

Is the carnivore diet dangerous?

Some of the benefits influencers claim might actually be red flags, Beckett points out. She takes particular umbrage with Ma’s claim that she never farts and only poos once a week. “This is the weirdest brag ever, because we need to fart and we need to poop, and if you are not farting, then there is something not right in your gastrointestinal tract.”

Associate professor Emma Halmos, a research dietitian at Monash University, clinically sees a lot of patients who have followed the carnivore diet and similar variations (keto and paleo) who are not eating enough fibre and have subsequently developed gastrointestinal symptoms or gastrointestinal disease. As a dietitian who only sees people with gastrointestinal conditions, she acknowledges there is a bias.

Often her clients have gone on the carnivore diet because they believe it is healthy and will help them lose weight. Because the carnivore diet is a zero carbohydrate diet, people can lose weight on it, but that doesn’t make it a healthy diet, Halmos says.

People can only absorb about 30 grams of protein in a sitting, Halmos says. The body excretes the protein it doesn’t absorb. When there are very large amounts, it can have negative effects, particularly for the large intestine, which goes through a process called putrefaction. “What that means is that it suppresses good bacteria and it changes the pH of the bowel so that nasties can grow,” Halmos says. The theory is that too much excreted protein can lead to bowel disease but we don’t have the evidence to back that up, she says.

How much meat is healthy?

The Australian Guide to Healthy Eating recommends up to three serves of meat or meat alternatives a day. “Three serves is way, way, way less than what we think,” Halmos says. Having meat once a day for most people would actually tick their requirements, meaning a lot of us actually exceed our requirements for meat,” she says.

The fact that some carnivores have turned to the diet after being vegan, Beckett says, “speaks to what are the real motivations for following the diet. Is it truly about health? Or is it about having a simple set of rules to follow … It creates a sense of community.”

A lot of people have decision fatigue where there’s so many food choices to make, and these diets make life feel easier, Beckett says. She recommends if people feel overwhelmed they can consult a health practitioner such as a dietitian who can help them develop what’s known as “nutritional self-efficacy”: feeling that you have the skills and the confidence to be able to make food decisions in any given environment.

• Natasha May is Guardian Australia’s health reporter

• Antiviral is a fortnightly column that interrogates the evidence behind the health headlines and factchecks popular wellness claims