GLP-1 Drugs and Bone Density: What the Latest Research Says About Semaglutide, Tirzepatide, and Your DEXA Scan

GLP-1 drugs like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro) have transformed weight management, but emerging research raises an important question about bone density. A growing body of evidence from 2026 shows that rapid weight loss on GLP-1 receptor agonists may reduce bone mineral density in certain patient groups, making a bone density DEXA scan an essential part of treatment monitoring.

At DEXA London, our Harley Street clinic provides the precise bone density measurements needed to track these changes before they become clinically significant. Whether you are already taking a GLP-1 medication or considering one, understanding how these drugs interact with your skeletal health is a decision that starts with data.

Quick Answer

GLP-1 receptor agonists such as semaglutide and tirzepatide can reduce bone mineral density by 2 to 3 percent at the hip and lumbar spine over 12 months, particularly in postmenopausal women and adults over 75 without type 2 diabetes. However, in people with type 2 diabetes, semaglutide has been associated with a 15 percent reduction in fracture risk. A DEXA bone density scan before starting treatment and at 12-month intervals provides the clinical data needed to detect changes early and guide protective interventions.

Bone is living tissue that constantly remodels itself through a balance of formation and resorption. When you lose weight rapidly, regardless of the method, your skeleton adapts to the reduced mechanical load by slowing bone formation and, in some cases, accelerating bone breakdown.

GLP-1 receptor agonists produce substantial weight loss, often 15 to 25 percent of body weight over 12 to 18 months. That magnitude of change reduces the gravitational and muscular forces acting on bone. Research presented at ENDO 2026, the Endocrine Society’s annual meeting, confirmed that once-weekly semaglutide raised bone resorption markers and produced lower hip and spine bone density at 52 weeks in adults at increased fracture risk.

The mechanism is partly mechanical (less body weight pressing on the skeleton) and partly metabolic. GLP-1 receptors are expressed on osteoblasts, the cells responsible for building new bone. While some laboratory studies suggest GLP-1 signalling may support bone formation, the net clinical effect during rapid weight loss appears to tip the balance towards resorption in vulnerable populations.

Clinical Note: Bone resorption markers such as CTX (C-terminal telopeptide) and P1NP (procollagen type 1 N-terminal propeptide) can be measured via blood test alongside your DEXA scan to give a more complete picture of bone turnover during GLP-1 treatment.

The evidence on GLP-1 drugs and bone density is more nuanced than early headlines suggested. Three key findings from 2026 shape the current clinical picture.

In postmenopausal women and older adults without diabetes, once-weekly semaglutide was associated with a 2.1 percent decrease in lumbar spine bone mineral density and a 2.6 percent decrease at the hip over 52 weeks. These reductions are clinically meaningful because they occur on top of the age-related bone loss already happening in this population.

In people with type 2 diabetes, the picture is different. A study presented at ENDO 2026 by the Endocrine Society found that semaglutide was associated with a 15 percent reduction in bone fractures compared with other anti-obesity medications. The likely explanation is that improved glycaemic control and reduced systemic inflammation offset the mechanical effects of weight loss on bone.

Across broader GLP-1 user populations, approximately 4 percent of users developed osteoporosis compared with just over 3 percent of non-users, representing a roughly 30 percent increase in relative risk. Women and adults aged 75 and older without type 2 diabetes appear to carry the highest risk of hip fractures on these medications.

These findings underscore why a one-size-fits-all approach to GLP-1 prescribing is inadequate. Your individual bone density baseline, measured by a DEXA scan, determines whether you fall into a higher-risk or lower-risk category before treatment begins.

Not everyone taking a GLP-1 medication faces the same skeletal risk. The following groups should prioritise bone density monitoring with a DEXA scan before and during treatment:

• Postmenopausal women: Oestrogen decline already accelerates bone loss. Adding rapid weight loss compounds the effect, particularly at the hip and spine.
• Adults over 65: Age-related sarcopenia (muscle loss) reduces the mechanical loading that stimulates bone maintenance. GLP-1-induced weight loss can accelerate both muscle and bone decline simultaneously.
• People with pre-existing osteopenia or osteoporosis: A T-score already below -1.0 means less bone reserve to absorb further losses.
• Those with a history of fragility fractures: Prior fractures indicate compromised bone architecture that may worsen with rapid weight reduction.
• Individuals on long-term corticosteroids or other medications that cause bone loss: Combining these with GLP-1 treatment creates cumulative skeletal risk.
• People with low vitamin D or calcium intake: Nutritional deficiencies impair the body’s ability to maintain bone during periods of metabolic change.

If you fall into any of these categories, a baseline DEXA scan before starting GLP-1 treatment is strongly recommended by endocrinologists and rheumatologists.

A bone density DEXA scan is the gold standard method for measuring bone mineral density at the hip, lumbar spine, and forearm. It provides a T-score that compares your bone density to a healthy young adult reference, and a Z-score that adjusts for your age and sex.

Before starting GLP-1 treatment: A baseline DEXA scan establishes your starting bone density. This is the reference point against which all future changes are measured. Without it, there is no way to know whether any bone loss detected later is related to the medication, to ageing, or to other factors.

At 12 months: A follow-up scan measures whether bone density has remained stable or declined. A loss of more than 3 percent at any site in 12 months is considered clinically significant and may prompt your prescribing doctor to adjust your treatment plan.

Ongoing monitoring: For patients remaining on GLP-1 drugs long-term, annual or biennial DEXA scans provide the longitudinal data needed to detect trends before they reach the threshold for osteoporosis.

At DEXA London, bone density results are reported by UK consultant rheumatologists at Medica, ensuring clinical-grade interpretation. The scan itself takes approximately 10 minutes and involves minimal radiation, roughly equivalent to a day of natural background exposure.

Bone loss during GLP-1 treatment is not inevitable. Several evidence-based strategies can help preserve skeletal health while you benefit from the metabolic advantages of these medications.

Resistance training is the single most effective intervention. Weight-bearing and muscle-strengthening exercises create the mechanical loading signals that stimulate bone formation. The Royal Osteoporosis Society recommends at least two sessions per week targeting the major muscle groups. A body composition DEXA scan can track both your muscle mass and bone density simultaneously, helping you and your trainer optimise your programme.

Adequate protein intake supports both muscle preservation and bone matrix formation. We explored this in detail in our guide to muscle loss with GLP-1 and GIP agonists and how a DEXA body composition scan can help. Current evidence suggests 1.2 to 1.6 grams per kilogram of body weight daily during active weight loss, which is higher than the general population recommendation.

Calcium and vitamin D remain foundational. The NHS recommends 700mg of calcium daily for adults and 10 micrograms (400 IU) of vitamin D, though many endocrinologists recommend higher supplementation during GLP-1 treatment, particularly in winter months when UV exposure is limited in the UK.

Gradual weight loss rather than rapid reduction appears to be more protective for bone. Some clinicians advocate for slower dose escalation of GLP-1 drugs in patients with borderline bone density, allowing the skeleton more time to adapt to the changing mechanical environment.

If your DEXA scan reveals declining bone density while taking a GLP-1 medication, this does not necessarily mean you should stop treatment. It means your prescribing doctor needs the data to make an informed decision about dose adjustment, protective interventions, or additional monitoring.

At DEXA London, we see patients referred by their GLP-1 prescribers specifically for bone density monitoring. Your scan results are delivered as a detailed clinical report that your doctor can use to weigh the metabolic benefits of continued treatment against skeletal risk.

If you are considering starting a supervised weight-loss programme with Mounjaro (tirzepatide), CutKilo, the sister service to DEXA London, offers doctor-led treatment from Dr Emil Gadimali. Because CutKilo and DEXA London operate under the same clinical team, bone density monitoring is integrated into your weight management journey from day one. Start the CutKilo questionnaire to see if you are suitable.

Do GLP-1 drugs cause osteoporosis?

GLP-1 drugs do not directly cause osteoporosis, but the rapid weight loss they produce can reduce bone mineral density by 2 to 3 percent per year at the hip and spine in higher-risk groups. In people with type 2 diabetes, semaglutide has actually been associated with reduced fracture risk. A DEXA bone density scan before and during treatment is the most reliable way to assess your individual risk.

Should I get a DEXA scan before starting Mounjaro or Ozempic?

Yes, a baseline DEXA scan is recommended before starting any GLP-1 medication, particularly if you are postmenopausal, over 65, have a family history of osteoporosis, or take other medications that affect bone. The scan provides the reference point needed to detect any treatment-related changes at your 12-month follow-up.

How often should I have a bone density scan while on GLP-1 treatment?

Most endocrinologists recommend a follow-up DEXA scan at 12 months after starting GLP-1 treatment, then annually or biennially depending on results. If your baseline scan shows osteopenia (T-score between -1.0 and -2.5), more frequent monitoring may be appropriate.

Does tirzepatide affect bones differently from semaglutide?

Tirzepatide (Mounjaro) is a dual GIP/GLP-1 receptor agonist, and the GIP component may have bone-protective properties based on preclinical research. However, large-scale clinical data specifically comparing tirzepatide and semaglutide effects on bone density are still emerging. Until more evidence is available, bone density monitoring is recommended for both medications.

Can exercise prevent bone loss while taking GLP-1 medication?

Resistance training and weight-bearing exercise are the most effective interventions for preserving bone density during GLP-1-induced weight loss. The mechanical loading from these activities stimulates bone formation and counteracts the reduced gravitational stress from lower body weight. The Royal Osteoporosis Society recommends at least two strength-training sessions per week.

Do I need a GP referral for a bone density DEXA scan at DEXA London?

No GP referral is needed. You can book a bone density DEXA scan directly at our Harley Street clinic. The scan takes approximately 10 minutes and results are reported by UK consultant rheumatologists at Medica. You can share the report with your GP or prescribing doctor.

Whether you are about to start GLP-1 treatment or want to check how your bones are responding after months on medication, a DEXA bone density scan gives you the clinical data to make informed decisions with your doctor.

DEXA London at 3Beam Diagnostic Imaging Centre, 86 Harley Street, London W1G 7HP.
Call: 0207 637 8227 | Email: scan@dexa.london
Book your bone density DEXA scan online. No GP referral needed.