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 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 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 Type 2 diabetes patients, there hasn’t been much study yet of what the diet can do for the general population.
If 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 keto 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.
Urologist Koushik Shaw at the Austin Urology Institute told Fox 7 Austin that he’s started noticing a worrisome trend.
“I’ve seen a huge spike in kidney stones,” Shaw said, mentioning that he hasn’t seen an uptick quite like this one before in his 14 years of practice. “A lot of it, I attribute to these high protein, low-carb, keto-type diets.”
He hypothesized that many of his patients are probably eating more meat and fish than they used to, which 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, needle-like 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 kidney stone-causing culprit.
“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 says a combination of “tons and tons of meat,” and not enough water can lead to kidney stones. Chi says while he hasn’t noticed any kind of dramatic uptick in kidney stone patients on keto plans, he has noticed a few extreme cases of stones in keto dieters.
“While that’s a pretty rare instance, 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, he said.
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, and brainstorm the best things to eat on the plan to stay healthy.
Chi says with so many patients telling him they’re having success losing weight and feeling good on the diet, he doesn’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.
“The weight loss is great,” Shaw said. “But you have to balance that with a high fluid intake so you can wash some of the metabolic products out.”
One proven trick to help is adding lemon to water. The citrate inside keeps calcium molecules from sticking together.
Children who are put 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 get in the first place, and also 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.