Bone mineral density (BMD) is a measure of how much mineral content – mainly calcium and phosphorus – is packed into your bones. It can help to think of it as an indicator of your bone strength and resilience. Bones are living tissue, constantly being broken down and rebuilt and BMD reflects the balance between these two processes.
Higher density usually means stronger bones that are better able to withstand everyday stresses. Lower density suggests bones may be more fragile which can increase the risk of fractures, especially in later life. BMD naturally declines with age, but the rate of decline varies widely depending on genetics, hormones, lifestyle and your overall health.
How Bone Mineral Density Is Measured
The most common way to measure BMD is with a DEXA scan. This is done with you lying down while a low‑dose X‑ray passes over the body, focusing on the hip and spine areas where fractures can have the biggest impact on independence and mobility. The scan produces a T‑score which compares your bone density to that of a healthy young adult of the same sex and ethnicity.
- A score above -1 is considered normal
- Between -1 and -2.5 indicates low bone density (osteopenia)
- Below -2.5 suggests osteoporosis
What Your BMD Tells You
A BMD result isn’t just a number – it’s a snapshot of your bone health at that moment in time. It can highlight whether your bones are losing density faster than expected, leaving you at a higher risk of fractures. Low bone mineral density should be heeded as a warning that you need to take action to build it back up through improved nutrition, taking the right form of exercise and making some lifestyle changes.
If you have a DEXA scan that shows low BMD, you should tell your family members – in particular your parents, siblings or adult children – as osteoporosis often runs in families.
T-scores are not the same as BMD
T-scores and BMD found on a DEXA scan are related but not interchangeable when tracking changes – such as in response to treatment, disease progression, or stability in osteoporosis follow-up scans. Here’s why:
- BMD is the raw measurement from a DEXA scan, reported in grams per square centimetre (g/cm²) at sites like the spine, hip or forearm. This is the actual physical density of the bone.
- The T-score is a calculated value that compares your BMD to the peak bone mass of a healthy young adult of the same sex and ethnicity. The World Health Organisation uses T-scores as the standard measurement and this is the one most familiar to people who have a DEXA scan. It’s useful for initial diagnosis – with osteoporosis being less than -2.5 – but not ideal for serial monitoring, when BMD is a better gauge of bone strength and resilience.
Supporting Bone Density Through Diet
Food plays a central role in maintaining healthy bones. Calcium is the best‑known nutrient for bone strength, found in dairy products, fortified plant milks, leafy greens, almonds and tinned fish with soft bones. Vitamin D helps the body absorb calcium effectively: you can find it in eggs, oily fish and fortified foods. Protein supports the muscles that protect and stabilise bones. Magnesium, vitamin K and phosphorus also contribute to bone structure. A balanced, varied diet that includes these nutrients helps keep the bone‑building process running smoothly. Even small, consistent changes – like swapping sugary snacks for nuts or adding a portion of greens to your dinner – can support bone health over time.
Lifestyle Habits That Make a Difference
Everyday choices have a surprisingly strong influence on BMD. Smoking and excessive alcohol can accelerate bone loss, while maintaining a healthy body weight supports hormonal balance and bone strength. Good sleep, stress management and staying socially connected all play a part in supporting overall wellbeing, which in turn can help you maintain healthier habits.
Exercise and Movement for Stronger Bones
Bones respond to movement. Weight‑bearing activities such as walking, dancing, gardening and stair climbing encourage bones to renew themselves and become stronger. Resistance exercises – using bands, weights or your bodyweight – help build muscle which supports balance and reduces the risk of falls. Activities that improve coordination, such as yoga, tai chi or Pilates, can be especially helpful as we get older. The key is regularity: little and often is far more effective than occasional bursts of activity.
There is a lot you can do to improve your bone mineral density. Rather than being worried about a low bone mineral density measurement, consider it as your start point for taking positive steps to protect your bones. Starting today.