The Keto Diet Could Be Bad for Bone Health, Study Says

The keto diet has recently taken the world by storm, as many people have seen drastic weight loss from following the low-carb, high-fat diet plan. While you may see a lot of celebrities and "influencers" praising keto on social media, most health experts aren't so enthusiastic about the super-restrictive diet.

Doctors and dietitians have spoken out against the keto diet, as there are concerns that it can lead to negative health consequences over time. Some of these consequences include impaired heart health, digestive issues and nutritional deficiencies. New findings tell us we may be able to add "impaired bone health" to the list.

Previous studies have associated low-carb, high-fat diets with impaired bone growth, reduced bone mineral content, slower fracture healing and increased bone loss in children. However, most of these studies have occurred over a period of 24 hours to several days, and this study is the first to test the potential long-term effects of the keto diet on bone health.

Researchers from the Australian Institute of Sport and Harvard Medical School put 30 elite race walkers on either a ketogenic or high-carb diet for three and a half weeks, taking blood samples before and after to check for specific markers of bone health. All of the participants' meals were matched in terms of how many calories they consumed for their body weight. About half of the participants went on for further study by restoring carbohydrate availability to see if any impairments on bone health could be restored.

The results showed that following a ketogenic diet for just a few weeks led to a decrease in markers for bone metabolism and formation and an increase in markers of bone breakdown. The high-carb dieters didn't experience any change in these markers, on average.

Those in the keto diet group who went through further tests to see if bone health would improve after restoring carbohydrate availability generally only saw partial recovery. While the marker for bone breakdown returned back to normal, markers of bone formation and metabolism did not. The authors of this study say their research identified "clear and consistent effects on bone metabolism at rest and in response to exercise" which warrant for further study.

"Given the injury risks and long-term outcomes underpinned by poor bone health in later life, in athletes as well as individuals who undertake exercise for health benefits, additional investigations of the ketogenic diet and its role in perturbing bone metabolism are warranted," the authors said.

The Bottom Line

This study gives us yet another reason to be cautious of adopting the keto diet—even for a "quick fix." We should be hesitant to engage in any type of restrictive diet, even for short periods of time, as it can lead to yo-yo dieting and impaired health.

Additionally, any diet that asks you to eliminate or severely restrict healthy foods like fruit, whole grains, beans and starchy vegetables should be a red flag. It could be worth reaching out to a registered dietitian to find a healthy eating plan that allows for more wiggle room and balance of macronutrients.