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Is It Bad For Your Bones?

Can following a keto diet be bad for your bones? Every year, about 5% of Americans decide to eat a keto diet and those who follow it to the letter, often see drastic weight loss from eating low-carb, high-fat meals. But there are some severe long-term health risks to following a keto diet, like an increased risk of heart disease, cancer and Alzheimer’s. I wondered, “if a keto diet is dangerous for so many disease, would it be bad for bones, too?”

In case you aren’t aware, a ketogenic diet, or keto diet, is an eating plan low in carbs and protein and very high in fat. Many studies have proven that a keto diet can help you lose weight and positively impact certain health problems like metabolic syndrome, diabetes and epilepsy.

Nutrients, May 2021

While there are a few versions of a keto diet, the standard keto diet is the most restrictive, with participants eating meals consisting of 70% fat and only 10% carbs. Sometimes athletes will cycle keto days with higher carb days and often individuals will flex the rules a bit and consume more protein and reduce their fat intake slightly. Only the standard and higher protein ketogenic diets have been studied extensively so I’ll focus on those research findings.

So, is a keto diet hard to follow? According to 2020 statistics, almost half of keto diets cheat at least sometimes or often. (46%) citing the main reasons as cheating because a particular kind of dessert was offered, there was a special occasion, or the choices were challenging when they traveled or dined out.

The foods they enjoyed the most were bread, pasta, desserts, potatoes, wine, and beer, which made it impossible to meet the daily 50 grams of carbs limitation. Eating more than 50g of carbs sends you out of ketosis and you must begin again, going through the process of headaches, fatigue, and nausea usually experienced when first starting the keto diet. They call that the keto flu. So basically, you just can’t cheat during the keto diet.

Animal models show that in chronic keto states, calcium concentrations are lowered, the kidneys can’t convert bone-preserving vitamin D, and there is an increase in osteoclastic activity, so cells are breaking down bones more quickly than cells are building up bones.

We see similar results in humans. Researchers in Australia put elite athletes on a keto diet for 3 ½ weeks/ After just a few weeks, bone formation went down, and bone breakdown went up.  The athletes had a higher rate of minerals being released from bones, before, during, and after prolonged race-walking. Further testing to see if bone health would improve after giving them carbohydrates showed that while bone breakdown returned to normal, bone formation and metabolism did not. 

Front Endocrinol, Jan 2020

Earlier studies in children with seizures have associated low-carb, high-fat diets with impaired bone growth, reduced mineral content with slower fracture healing times, and increased bone loss. It is important to note these studies only lasted 1-3 days, and perhaps longer-term studies would show something else.  

Epilepsy Res, Oct 2017

On the flip side, other experts suggest that even if the bone mineral density in children and adults is low, that doesn’t necessarily correlate to fracture risk. Bone health and remodeling can be impacted by many factors. Researchers also suggest that epilepsy drugs or immobilization may contribute to negative bone health, for example. If nutrients are inadequate, that could be a factor too. This is supported by an older study at the University of South Florida also found that adults following a strict low-carbohydrate diet had no bone loss issues.

As a registered dietitian, I don’t believe that the keto diet is beneficial for long-term health. I do want to suggest that biomarkers of bone health can still give clues about potential bone breakdown and fracture risk. Osteoporosis International, May 2006 This is precisely why it’s important to get a personalized nutrition plan, so you can make sure that what you are doing is supporting your health goals, and not harming you in other ways.

So, for right now, the idea that a keto diet increases bone loss can’t be supported, and more studies on humans are needed. That said, since the keto diet can cause damage down the road, I recommend three things:

  1. If you choose to follow a keto diet, do so for a short period of time only.
  2. Consider trying intermittent fasting for weight loss first. This is kinder on the system, has proven effects in terms of bone health, and is easier to follow.
  3. Regardless of which diet you follow, add plant powders into your diet to fill in the gap of restricted dietary choices. The dietitians at CNIQ recommend the most science-based plant powders that make it easy to help your body function more optimally and get the bone-supporting nutrients you need every day. I’ll drop a link in the comments section.

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