Low-carb diets have many iterations, each with a devoted following. Atkins dieters eat lots of meat and eggs before slowly and carefully reintroducing carbs, while the ketogenic diet urges people to severely cut carbs and focus on upping their fat intake from foods like butter, cheese, and avocados.
But increasingly, scientists are discovering that going low-carb may not do you any favours in the long run.
A study presented on Tuesday at the European Society of Cardiology Congress 2018 looked at the self-reported eating patterns of 24,825 people in the US over more than a decade.
The researchers separated participants into four quartiles, from lowest- to highest-carb diets. They found that Americans in the bottom 25% of the pack, who ate barely any carbs, had a 32% higher risk of death from any cause than those who had the highest carb intakes.
They also found that low-carb dieters had a 51% increased risk of dying from coronary heart disease and a 35% increased risk of dying from cancer relative to people in the top 25% of carb eaters.
The researchers compared those results with data on the diets of 447,506 people around the world and found that overall, low-carb dieters had a 15% increased risk of death.
The researchers think this may be because replacing healthy, fibre-rich carbs — like whole grains and certain vegetables — with more meat can lead to danger.
"Our study suggests that in the long-term they are linked with an increased risk of death from any cause, and deaths due to cardiovascular disease, cerebrovascular disease, and cancer," Maciej Banach, a professor at the Medical University of Lodz in Poland who helped write the study, said in a release.
This new study comes on the heels of another worldwide investigation into death data published in the Lancet earlier this month. It found that people who ate a moderate amount of carbs and focus on whole, healthful foods like veggies, legumes, and nuts tended to live longer than people who limited their carbohydrate intake.
It's more evidence that the best long-term diet strategy is a regimen rich in vegetables, filling whole grains, and healthy fats from naturally oily sources like olives and avocados.
"Try to make choices that fill your plate with plants," Sara Seidelmann, a cardiologist and nutrition researcher at Brigham and Women's Hospital in Boston who led the Lancet study, previously told Business Insider.
She said it's not clear whether a plant-based diet that is also low-carb might be a healthy long-term strategy because no one really eats that way.
"It's not a natural eating pattern," she said.
Instead, when people dump carbs, they often reach for more animal proteins and fats.
Eating more butter and meat can increase your blood pressure, and the World Health Organisation says that processed meats like hot dogs, ham, bacon, and sausage can cause cancer. It's possible that any kind of red meat, processed or not, could be linked to an increased risk of colorectal cancer. And some fish carry high levels of nitrates, which can cause cancer in animals.
What's more, low-carb dieters who trade grains and fresh produce for more meat and fish may unwittingly acidify their urine, putting them at risk for developing kidney stones.
Still, low-carb diets offer real benefits for certain people.
The ketogenic diet — keto for short — was originally developed to help curb epileptic seizures in children. Cutting sugar and eating more fat has been found to help control seizures when drugs can't and to stop them completely in some cases.
Going keto can also help control blood glucose levels in adults with Type 2 diabetes. That's also why it can be an effective short-term weight-loss treatment.
"Low-carbohydrate diets might be useful in the short term to lose weight, lower blood pressure, and improve blood glucose control," Banach said in the release. His study suggests that the link between early death and low-carb diets is stronger for people who aren't obese, lending credence to the idea that it might be all right to cut carbs if you need to lose a lot of weight.
Cancer doctors also think that keto diets may play a role in making certain types of treatment more effective, and they've studied how cutting sugar from mice's diets helps one class of cancer drugs more effectively kill tumours. Human trials of this drug-diet combo are set for later this year.
But for most people, restricting carbs is done by ramping up their intake of meat and other proteins and forgoing high-fibre, carb-heavy foods like beans, carrots, and legumes that help keep you satisfied until your next meal.
That said, cutting back on carbs does help dieters eat healthier in one important way: It reduces their sugar intake.
Sugar is essentially all carbs, and research has clearly shown that eating sugar can lead to all kinds of health problems — like weight gain, heart disease, high blood pressure, and diabetes — if left unchecked.
"If we're talking about a Mountain Dew from 7-Eleven, I would agree that carbohydrate in that context is bad," Edward Weiss, an exercise scientist, recently told Business Insider. But he said that processed carbs like white bread and sugary snacks that lack fiber and vitamins shouldn't be equated with healthy carbs like whole vegetables and whole grains.
"These are the healthiest foods we know of," he said. "To avoid them is, I think, really taking a chance and doing self-experimentation with something that might have long-term negative effects."
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