Kim Kardashian says the Atkins diet was the secret to her post-baby weight loss, and plenty of studies have suggested that eating a high-protein diet can help you drop pounds. But there’s a potential drawback to be aware of: A new study suggests that consuming a diet packed with protein can boost your chances of developing kidney disease and/or painful kidney stones.
Here’s the gist: Scientists at the University of Grenada in Spain fed rats a diet composed of 45 percent protein for 12 weeks. The rats did lose weight—10 percent of their total body weight, in fact. However, they had significantly lower levels of a chemical found in urine that prevents the crystallization of calcium—and having this sort of deficiency can lead to kidney stones.
This isn’t the first time researchers have found fault with high-protein plans, especially when it comes to kidney problems. There’s been a rise in the incidence of kidney stones—and the American Academy of Family Medicine released a statement linking this to the popularity of diets high in animal protein, says Janet Brill, Ph.D., R.D., a Philadelphia-based nutritionist. Animal protein produces an acidic environment in the body, increasing the formation of kidney stones and leeching calcium from bones, says Brill. “Plant proteins don’t have the same effect."
Unsurprisingly, the study authors came down hard on high-protein diets in general—but they singled out the Dukan Diet by name. (While the study authors didn’t go into why they called out this diet in particular, it may be because the weight-loss plan is trendy in Europe—and the researchers are from Spain). It’s also worth noting that animals’ bodies aren’t identical to humans’—so this animal study alone doesn’t prove that high-protein diets will have a similar effect on people.
While it’s best to avoid diets that cut out entire food groups and instead opt for more sustainable healthy-eating plans, the study authors did say that there may be a way to offset the possibility of kidney problems if you’re consuming tons of protein: Make sure to eat lots of fruits and vegetables since they’re high in potassium (and the nutrient can help protect against kidney stones).