The real dangers of low-carb dieting fads, according to the latest science

The craze around carbs.
The craze around carbs.
Image: Reuters/Stefano Rellandini
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A popular method for losing weight in the short-term may come with a hefty long-term price tag.

That’s according to new research presented this week at the world’s largest heart-health conference, held in Munich. It was there that scientists from the Medical University of Lodz in Poland delivered a stark message about eating regimens low in carbohydrates such as bread, pasta, potatoes, and rice.

“These diets should be avoided,” said the author of the new study, Maciej Banach, in a statement. “We found that people who consumed a low-carbohydrate diet were at greater risk of premature death.”

Specifically, those people were more likely to die prematurely by coronary heart disease, stroke, and cancer, according to the study. The finding jives with another study published earlier this month in the journal The Lancet, which found higher mortality rates among people who ate especially low- and high-carb diets.

Until recently the long-term effects of popular low-carb diets have been something of a mystery. Scientists generally find and agree they are an effective way to lose weight. But reporting that there’s an increased risk to illness-induced death has been—and still is—controversial. Largely that’s due to the nature of nutrition science. Because nutrition researchers can’t treat human subjects like lab rats, they often have to rely on observational studies, which can be difficult to analyze because they are less controlled and typically depend on self-reported surveys.

The results of the latest low-carb diet study further complicate the dieting landscape for everyday people seeking ways to switch up what they eat in order to live healthier lives. Committing to a nutritional path toward better wellbeing is hard enough as it is, and isn’t made any easier by the cacophony of competing options, many of which claim scientific integrity at odds with the science-based claims of other dieting techniques. For instance, major components of the low-carb, high-in-meat keto and paleo diets are inherently contradictory to the population-sized researched published in The China Study. In that 2006 book, Cornell University scientists concluded that low-meat, high-in-veggies diets are most healthful, and argued that we need to eschew low-carb options such as the Atkins diet.

Still, the most recent study out of Europe commands the heft of a broad sampling of people, which makes it worth closer inspection. The scientists used a nationally-representative sample of almost 25,000 people, all of whom partook in the US National Health and Nutrition Examination Survey (NHANES) between 1999 to 2010. After comparing people with the highest carbohydrate consumption to those with the lowest, the researchers found a 32% higher risk of premature death among those who ate low-carb diets.

The results were set against and confirmed by a meta-analysis of seven other nutrition studies that, combined, included more than 447,000 participants. Together, those studies found people with low-carbohydrate diets experienced 15%, 13%, and 8% increased risk of death from heart disease, cerebrovascular disease, and cancer, respectively.

Banach did note that as part of many low-carb diets, people reduce the amount of fiber and fruits they eat while increasing their intake of red meats, and that might explain the increased risk of premature death. After all, he said, red meat has been linked to increased risk of ailments such as heart disease and cancer. But if the protein in a low-carb diet were to come from plant-based foods instead of meat, it might not be as dangerous, he said in the study.