Understanding Bone Density Risks on Mounjaro

Weight loss medications like Mounjaro (tirzepatide) have revolutionised weight management in the UK, but rapid fat loss can have unintended consequences for bone health. Recently, some headlines have warned of "weakened bones", but few resources explain the underlying mechanisms, monitoring strategies and effective ways to protect the skeleton. Here is what you need to know.

How Weight Loss Affects Bone Health

During weight loss, the body breaks down muscle and bone proteins faster than they can be rebuilt. Reduced mechanical stress on bones, due to lower body weight, can decrease bone formation and increase bone resorption, leading to a net loss in bone mineral density (BMD).
Although Mounjaro and other GLP 1 medications are highly effective for fat loss, rapid reductions in body mass may accelerate bone loss, especially if diet and exercise are not carefully managed.

What Do We Know About Mounjaro and Bone Density?

  • Clinical data: Current clinical trials and post marketing surveillance have not found a clinically significant increase in bone fracture risk with Mounjaro, and the prescribing information from the manufacturer does not list bone loss as a known side effect.However, long term data are still limited due to the medication being relatively new to the market, and the potential for bone loss remains a concern due to the way the body responds to rapid weight loss.
  • Osteoporosis considerations: People with osteoporosis or at risk of low bone density can still use Mounjaro, but they should aim for gradual weight loss, maintain a protein rich diet and engage in regular weight bearing exercise.

Monitoring Bone Health on Mounjaro

  • Who should monitor: Anyone with a history of osteoporosis, previous fractures or other risk factors for bone loss should discuss bone density monitoring with their healthcare provider before starting Mounjaro treatment.
  • How to monitor: Bone mineral density can be tracked using DEXA scans, especially for those on long term therapy or experiencing rapid weight loss. Regular blood tests for calcium and vitamin D may also be recommended. This should be discussed with a GP or healthcare provider.

Mitigating Bone Loss: Evidence Based Strategies

  • Resistance and weight bearing exercise: Exercise is one of the most effective ways to preserve bone health during weight loss. Resistance training and weight bearing activities such as walking, jogging and strength training stimulate bone formation and help maintain muscle mass.
  • Protein intake: A higher protein diet supports both muscle and bone health. Aim to include adequate protein with each meal, focusing on whole food sources.
  • Targeted supplementation: Ensure sufficient intake of calcium and vitamin D, either through diet or supplements, particularly if dietary sources are limited. Speak to your healthcare provider if you are concerned about not getting enough calcium or vitamin D.
  • Gradual weight loss: Rapid weight loss increases the risk of bone loss. A slower, steadier approach of around 0.5 to 1 pound per week is safer for bone health.

Key Takeaways

  • Mounjaro is generally safe and effective for weight loss when prescribed and monitored by a healthcare professional.
  • Rapid weight loss, regardless of method, can compromise bone density, particularly if not paired with proper nutrition and exercise.
  • Bone health can be protected by combining gradual weight loss, resistance training and a diet rich in protein, calcium and vitamin D.
  • Speak to your healthcare provider about your individual risk factors and monitoring plan before and during Mounjaro treatment.

Always consult your doctor before making changes to your medication, diet or exercise routine.

You can find more information about Mounjaro and other weight loss treatments on medino’s clinic pages.

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Written by Henrik Blomkvist
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