The keto diet, at its essence, is rather straightforward: stop eating carbs, munch on more fat.
It is a high-fat, low-sugar weight-loss strategy that forces the body into its natural starvation mode, causing it to rely on fat for fuel instead of on sugars and carbohydrates — typically what our bodies like to burn through first.
Some people say it lifts mental fog while slimming their waistlines. Different versions of the plan have picked up a string of celebrity followers, from Kim Kardashian West to LeBron James. The diet is especially popular among Silicon Valley tech workers, who see it as a path to better performance and reduced appetite, albeit with a side of bad breath.
But while decades of research suggest that a keto regimen can treat epileptic seizures and control blood glucose levels in people with Type 2 diabetes, there hasn’t been much study yet of what the diet can do for a wider population.
If keto dieters aren’t careful, they can quickly become dehydrated, ramping up the amount of protein and uric acid in their body to dangerous levels. The diet itself has not been linked to an increase (or decrease) in kidney stone diagnosis rates, but some doctors say they’re already seeing a shift as more of their patients go keto.
[Our reporter spent two months on the keto diet. Here’s what it was like]
Dr. Koushik Shaw, a urologist at the Austin Urology Institute, told a local Fox affiliate he had started noticing a worrisome trend.
“I’ve seen a huge spike in the number of kidney stones that we see,” Shaw said, adding that he hadn’t seen an uptick quite like this before in his 14 years of practice.
“A lot of it I attribute to a lot of these high-protein, low-carb, keto-type diets,” he said.
He hypothesized that many of his patients were probably eating more meat and fish than they used to, something that can increase calcium and uric acid levels and acidify their urine.
“All of these things can contribute to a higher rate of kidney stones,” he said.
Higher levels of uric acid in the body can also lead to other health problems, like gout, which can happen when uric acid builds up in the body, “forming sharp, needlelike urate crystals in a joint or surrounding tissue that cause pain, inflammation and swelling,” according to the Mayo Clinic.
Other doctors aren’t sure that the keto diet is the true culprit behind the kidney stones.
“Some of the problem might lie in the way that people interpret the keto diet,” Dr. Thomas Chi, a urologist at The University of California, San Francisco, told Business Insider.
He said a combination of “tons and tons of meat” and not enough water could lead to kidney stones.
And Chi said that while he hadn’t noticed any kind of dramatic uptick in kidney stone patients on keto plans, he had seen a few extreme cases of stones in keto dieters.
“While that’s a pretty rare instance,” he said, “it may be driven not necessarily by the fact that you’re having low carbs and higher fat but that you’re subbing in other things,” like more meat.
Fatty keto options like butter and meat can increase your blood pressure, while a higher protein intake can put added stress on kidneys, because it adds more acid to them and messes with the body’s balance of calcium.
Dietitians recommend anyone going on the keto diet consult with their doctor to discuss whether it’s the right choice for their body type and medical history, as well as brainstorm the best things to eat on the plan to stay healthy.
The doctor-recommended way to go keto
Chi said that with so many patients telling him they’re having success losing weight and feeling good on the diet, he didn’t want to discourage a helpful-eating shift.
“I generally tell people, ‘Everything in moderation,'” he said. “We try to take a pragmatic approach.”
He recommends his patients stay well hydrated and don’t overdo it on the meat.
Shaw said: “The weight loss is great and lower carbohydrates are great. But you have to balance that with a high fluid intake so you can wash some of the metabolic products out.”
Something that can help is adding lemon to water, Shaw said, because the citrate in the lemon keeps calcium molecules from sticking together.
Children on the keto diet to help control seizures are sometimes given oral potassium citrate tablets, which can both help decrease the number of stones they develop and prolong the time it takes stones to form.
So while there’s no clear evidence that a keto diet directly causes more kidney stones, it’s a good idea to check whether you’re at an increased risk for developing stones before you go keto.