Could weight loss medication lead to a rise in osteoporosis?

A top doctor has warned against the use of popular weight loss drugs such as Wegovy and Mounjaro for people who suffer from weakened bones.
An estimated 12% of adults in Britain have taken the class of drugs known as GLP-1 agonists such as semaglutide, which are used for weight loss and to treat diabetes or lower the risk of cardiovascular diseases.
And according to new reports, unemployed people will be given weight-loss jabs under Government plans to get them back to work.
But Dr Taher Mahmud, Founder of the London Osteoporosis Clinic said we must be “cautious of the long-term impact on muscle and bone health.”
He said: ““The weight loss benefits of GLP-1 agonists are undeniable, but the evidence also shows loss of lean mass and bone density which is concerning, particularly for patients with conditions like osteoporosis, who are already vulnerable to fractures.
“Tackling obesity is something we as a nation must address and being overweight puts pressure on our bones and joints. But it is essential that we combine medicine with education and support to ensure that those taking GLP-1 agonists know about the importance of good nutrition and weight-bearing exercise.
“Incorporating these strategies into daily life will help to mitigate these effects whilst enjoying the benefits of weight loss.”
Emerging studies presented at the 2024 Annual Meeting of the American Society for Bone and Mineral Research (ASBMR) raised significant concerns about the potential side effects of these treatments, specifically regarding lean mass and bone density loss.
Clinical trials demonstrate that nearly 70% of participants using these medications achieved a reduction of 10% or more of their body weight over a 68-week treatment period. These outcomes have made these drugs invaluable for individuals battling obesity, with promising improvements in cardiovascular and metabolic health.
However, alongside these successes, new data indicates that up to 30% of the weight loss achieved through GLP-1 agonists may come from lean mass, posing a risk to long-term physical functionality.
Furthermore, studies have highlighted a potential reduction in bone mineral density in the hip and spine of patients undergoing treatment, particularly when the medication is not coupled with exercise.
“This data raises a key concern for those people who already have an elevated risk of osteoporosis or fractures, such as those with obesity or type 2 diabetes,” says Dr Mahmud.
“These patients are most likely to be prescribed these medications, so it is essential they are aware of the risks and how to mitigate them.”
Dr Mahmud has devised four essential guidelines he believes clinicians must advise patients on GLP-1 agonists to follow.
Targeted Prescriptions: Before prescribing GLP-1 medication, a patient’s overall health profile must be considered – not just their BMI and diabetes profile but bone density and fracture risk.
Exercise and Resistance Training: All patients embarking on a weight-loss journey will be encouraged to take part regular physical activity as part of a long-term approach to weight loss and weight management. But the importance of strength training as well as cardiovascular exercise should be promoted to help protect against muscle and bone loss.
Nutritional Strategies: Patients experience a significant drop in appetite when taking these medicines so it is important that we educate patients on the importance of eating enough protein to preserve lean mass during weight loss. Free trackers can help patients calculate their ‘macros’ – or the percentage of their diet which can be broken down into the major food groups such as carbohydrates, protein and fats.
Close Monitoring: Regular assessments of body composition and bone health, particularly in elderly or high-risk patients, is essential to monitor the progress of patients and ensure that weight loss is not coming at the cost of lean muscle and weakened bones.

The research into the effects of these medications must still be continued, argues Dr Mahmud.
“We must better understand the risks associated with these treatments and develop strategies to protect our patients’ musculoskeletal health. Future studies should explore therapies that could be used alongside GLP-1 agonists to safeguard against bone loss.”