You may have seen celebrities advocating meat-only diets claiming they were cured of chronic diseases and naturally helped them stay slim.
To people who are into health research, these diets seem … dubious.
They are sure to violate Australian dietary guidelines that prioritize fruits, vegetables and grains and recommend limiting animal products to a few servings per day.
And for some people, eating meat or even animal products is absolutely off the table for ethical or environmental reasons.
Suppose you have decided on a meat diet. Would it be possible to get everything you need? And how new is this idea really?
On paper, the carnivore diet looks OK
The carnivore diet takes the low-carb approach of Paleo, Keto, or Atkins to a new level, cutting out everything but animal products.
There are variations: some people only eat beef, others eat a wider variety of meats, and whether cheese and butter are on the menu also varies between followers.
But if we approach the question solely from a health point of view, is it even possible to get all the nutrients your body needs from animal products only?
The answer is yes or pretty close, says Veronique Chachay, a nutritionist from the University of Queensland.
She ran versions of a carnivorous diet through diet composition analysis software and found that pretty much all the necessary vitamins and minerals were taken into account, depending on the mix of animal feed in it.
"From a purely micronutrient point of view, we cannot say that people cannot meet their requirements," says Dr. Chachay.
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Ticking off nutrients is only part of the story. We know that fiber is important for digestive health and promotes a variety of beneficial gut bacteria – and fiber is particularly lacking in carnivorous diets.
Experts are therefore interested in learning more about the science why some people report feeling good about diets like these, even after following them for a long time.
We don't know much about the long-term effects of this diet, however, and scientists are calling for more research.
Lessons from the Inuit Diet
The Inuit – First Nations from rth rth America – traditionally eat almost exclusively animal products.
They are often cited as evidence that a carnivorous diet can be healthy. What does the Inuit diet actually look like?
In 2004, researchers conducted surveys of 18 indigenous communities in Canada where people were following or getting fairly close to the traditional diet.
They found that community members ate well over a kilogram of animal products per day and between 28 and 160 grams of plant-based foods per day.
The traditional Inuit diet relied heavily on animal foods, including land mammals, birds, and fish. (Unsplash: Joris Beugels)
Research shows it is possible to eat a diet very rich in animals, says Clare Collins, professor of nutrition and dietetics at Newcastle University.
"(The Inuit) had very low carbohydrate intake, very low vegetable intake in their traditional diet, and they ate some things that we would not eat, for example, they ate the organs of many animals, they ate a lot of seafood, and they ate some of their meat raw that actually contains more vitamin C, "she says.
"With some of these nutrients, they could meet their needs because they ate a lot of these foods."
But Inuit are not particularly long-lived. And while the factors that affect life expectancy are hard to pin down, especially when you study First Nations people in modern times, Professor Collins says major drivers come from diet.
"Life expectancy isn't high and they have very high rates of cancer. Part of this is due to their genetics. And that's made worse by a really high-salt, smoked diet."
In contrast, the traditional diets of the world's longest-lived peoples have very high vegetable intake, she points out.
But whatever traditional diet you look at, "they're all less refined foods," says Professor Collins.
"And that's the big thing that people don't really want to see."
The myth of an optimal diet
As with many diets, proponents of the carnivore diet often consider it the ideal way to eat.
And that's just not true, says Dr. Chachay because there is no such thing as optimal nutrition.
We humans are alike, but we are not clones. We have genetic differences. And just as some people can digest the lactose in milk and others cannot, there could be other differences that explain why some people report living on a carnivorous diet.
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Dr. Chachay's research looks in part at the potential for personalized diets based on an individual's unique genetic makeup and even the makeup of their microbiome. We're not there yet, but she's hoping it will happen in the near future.
"We will be able to tailor diets and ideal micronutrient ratios to suit optimal individual health."
And while the evidence on carnivore diets is sparse, she suspects that for some people it may work for their bodies.
"What interests me is that these people who practice it obviously haven't died after a year. They haven't lost their hair. They haven't gone completely insane. They work," she said.
"There will be a mechanism behind the scenes."