The DEXA Scan: The Gold Standard of Longevity Testing
- Aug 17
- 7 min read
Preventive healthcare begins with understanding your health before symptoms develop. While measurements such as body weight and Body Mass Index (BMI) can provide a useful starting point, they cannot distinguish between fat, muscle and bone, or reveal how these tissues change over time.
A DEXA scan offers a far more detailed assessment. The International Society for Clinical Densitometry (ISCD) recognises DEXA as the clinical reference standard for measuring bone mineral density, and it is also widely regarded as one of the most accurate methods of assessing body composition.
These objective measurements can establish a baseline, monitor changes over time and support more personalised conversations around nutrition, exercise, healthy ageing and preventive medicine.
At Reborne Longevity, DEXA scanning forms part of our evidence-led approach to longevity medicine, combining advanced diagnostics with expert clinical interpretation to help you make informed decisions about your long-term health.
WHAT IS A DEXA SCAN?
A DEXA scan, also known as Dual-Energy X-ray Absorptiometry (DXA), is a quick, non-invasive imaging test that measures both bone mineral density and body composition.
Originally developed to assess bone health, DEXA now measures:
Bone mineral density
Total body fat percentage
Lean muscle mass
Visceral fat
Regional body composition
Unlike bathroom scales or BMI, which provide only a single measurement, DEXA shows what your body is made up of.
THE HISTORY OF DEXA TECHNOLOGY
DEXA was introduced during the late 1980s as a more accurate, lower-radiation alternative to earlier bone density imaging techniques. Over time, advances in imaging software expanded its role beyond bone health, allowing clinicians to assess body composition with a high degree of precision.
Today, DEXA is widely used in hospitals, research institutions and preventive healthcare, with its role in body composition assessment well established in the clinical literature.
HOW DOES A DEXA SCAN WORK?
DEXA uses two very low-dose X-ray beams to distinguish between bone, lean tissue and fat. By analysing how each tissue interacts with the X-ray beams, the scanner produces a detailed picture of your body composition and bone mineral density.
During the examination, you lie on a padded scanning table while the scanner moves slowly above your body. The scanner remains open throughout the procedure.
The scan is painless, non-invasive and requires no recovery afterwards.
WHAT DOES A DEXA SCAN MEASURE?
Bone Mineral Density
Bone is constantly being broken down and rebuilt throughout life. As we age, this balance can change, leading to a gradual decline in bone mineral density.
DEXA is the internationally recognised method for measuring bone mineral density. The Royal Osteoporosis Society and NHS both recommend DEXA as the standard investigation for assessing bone health where clinically appropriate. Results are interpreted alongside your medical history and other clinical risk factors.
Body Composition
A DEXA scan measures total body fat, lean muscle mass and regional body composition, providing a much clearer picture of your health than body weight or BMI alone. It can also estimate visceral fat – the fat stored around the abdominal organs – which is considered an important marker of metabolic health.
These measurements allow clinicians to distinguish between changes in fat and muscle over time, making DEXA particularly valuable for monitoring healthy ageing, supporting medically supervised weight management and assessing the impact of nutrition and exercise programmes.
WHY IS A DEXA SCAN CONSIDERED THE REFERENCE STANDARD?
The International Society for Clinical Densitometry (ISCD) identifies DEXA as the clinical reference standard for measuring bone mineral density. It is also recognised as one of the most accurate and reproducible methods available for assessing body composition.
Unlike BMI, which estimates health using only height and weight, DEXA directly measures bone, muscle and fat tissue. It also provides more consistent results than many consumer body composition devices, which can be influenced by factors such as hydration or recent exercise.
Repeat scans performed using the same scanner allow clinicians to monitor changes over time with greater precision.
WHO SHOULD CONSIDER HAVING A DEXA SCAN?
A DEXA scan may be beneficial for a wide range of people, including:
Healthy adults wishing to establish a baseline assessment of their body composition and bone health as part of a proactive approach to healthy ageing.
Individuals undertaking medical weight management, where monitoring changes in fat and lean muscle provides a more meaningful measure of progress than body weight alone.
Athletes and physically active individuals who want to understand changes in muscle mass and body composition throughout training.
Adults with concerns about bone health or recognised risk factors for reduced bone density, where a clinician recommends assessment.
People interested in monitoring their health as they age.
Women, Perimenopause and Menopause
Women experience significant changes in body composition and bone health during perimenopause and menopause. As oestrogen levels decline, bone mineral density may reduce more rapidly, while body fat distribution often changes and lean muscle mass can gradually decrease.
A DEXA scan provides an objective way to monitor these changes. By measuring both bone density and body composition, clinicians can establish a baseline and track changes over time, supporting personalised discussions around nutrition, resistance exercise, healthy ageing and, where appropriate, medical management.
For women taking a proactive approach to long-term health, DEXA can form an important part of preventive healthcare by identifying measurable changes before they become clinically significant.
DEXA and Osteoporosis
Osteoporosis develops when bones gradually lose mineral density, becoming weaker and more susceptible to fracture. Because bone loss often occurs without noticeable symptoms, many people remain unaware until a fracture occurs.
DEXA is recognised internationally as the reference standard for measuring bone mineral density and plays an important role in assessing osteoporosis risk when clinically indicated. When interpreted alongside an individual's medical history and recognised risk factors, DEXA results help clinicians make informed decisions about ongoing monitoring and appropriate management.
Why Men Can Benefit from a DEXA Scan
DEXA is equally valuable for men, particularly those focused on maintaining performance, strength and long-term health.
Unlike body weight alone, DEXA distinguishes between lean muscle mass, body fat and visceral fat, allowing a much more detailed assessment of physical condition. For active individuals and athletes, repeat scans can help monitor how training, nutrition and recovery influence body composition over time.
For men approaching midlife, DEXA can also establish an objective baseline for monitoring age-related changes in muscle mass and bone health, supporting a more informed approach to healthy ageing.
WHAT HAPPENS DURING A DEXA SCAN?
After removing any large metal objects, you will lie on a padded scanning table while the scanner passes slowly above your body. The scanning arm remains open throughout the procedure and does not enclose you.
HOW LONG DOES A DEXA SCAN TAKE?
The scan itself usually takes between 10 and 20 minutes, although your appointment may be slightly longer to allow time for preparation and discussion of your results.
IS A DEXA SCAN SAFE?
Yes. DEXA scanning uses a very low dose of ionising radiation and is considered safe when clinically appropriate. The International Atomic Energy Agency (IAEA) states that the radiation dose is only a small fraction of normal background radiation.
As with any X-ray examination, you should inform your clinician if you are pregnant or think you may be pregnant before undergoing the scan.
UNDERSTANDING YOUR DEXA SCAN RESULTS
Following your appointment, you'll receive a report explaining your results. A body composition assessment typically includes:
Total body fat percentage
Lean muscle mass
Regional distribution of fat and muscle
An estimate of visceral fat
If your scan includes a bone density assessment, your report may also include T-scores and Z-scores. A T-score compares your bone mineral density with that of a healthy young adult of the same sex, while a Z-score compares your results with others of a similar age and sex. These measurements are interpreted according to internationally recognised guidance published by the International Society for Clinical Densitometry (ISCD), alongside your age, medical history and individual risk factors.
HOW OFTEN SHOULD YOU HAVE A DEXA SCAN?
How frequently you should have a DEXA scan depends on your health goals and clinical circumstances. The Royal Osteoporosis Society and International Society for Clinical Densitometry both advise that repeat scanning intervals should be based on individual clinical need rather than fixed timelines.
Where repeat scans are appropriate, using the same scanner provides the most reliable comparison over time.
DEXA SCANNING AT REBORNE LONGEVITY
At Reborne Longevity, DEXA scanning is integrated into our wider approach to preventive healthcare and longevity medicine. Rather than viewing the scan as a standalone investigation, we use it alongside your medical history, lifestyle and other advanced diagnostics to build a more complete understanding of your health.
DEXA forms part of our Human MOT philosophy, providing objective measurements that establish a baseline and help monitor changes over time. Whether assessing bone health, tracking body composition or supporting healthy ageing, these insights enable more personalised discussions around nutrition, exercise, metabolic health and preventive care.
Having an in-house DEXA scanner also allows our clinicians to incorporate body composition and bone density assessments seamlessly into our longevity programmes, creating a more convenient and integrated experience for patients.
As part of a comprehensive preventive health assessment, repeat scans performed using the same scanner can provide reliable comparisons over time, helping monitor measurable changes as your health journey evolves.
FREQUENTLY ASKED QUESTIONS
What is a DEXA scan?
A DEXA scan is a low-dose X-ray examination that measures bone mineral density and body composition, including body fat, lean muscle mass and visceral fat.
What does a DEXA scan measure?
It measures bone mineral density and body composition, including body fat, lean muscle mass and visceral fat.
How accurate is a DEXA scan?
DEXA is one of the most accurate clinical methods for assessing body composition and bone mineral density.
How long does a DEXA scan take?
Most DEXA scans take 10–20 minutes.
How is a DEXA scan performed?
You lie on a scanning table while the scanner passes above your body. The procedure is painless and non-invasive.
Do I need to prepare for a DEXA scan?
Very little preparation is required. Your clinician may advise avoiding calcium supplements for 24 hours beforehand and will ask if you may be pregnant.
Is a DEXA scan safe?
Yes. DEXA uses a very low dose of ionising radiation.
Does a DEXA scan involve radiation?
Yes, but the radiation dose is very low.
What do DEXA scan results mean?
Your clinician will explain what your results mean for your health and any appropriate next steps.
Who should get a DEXA scan?
DEXA may be suitable for adults interested in preventive healthcare, body composition or bone health.
Where can I book a private DEXA scan in London?
You can learn more about Reborne Longevity's DEXA Scan service and book an appointment through our website.
REFERENCES
International Society for Clinical Densitometry (ISCD). Official Positions. Available at: https://iscd.org
Royal Osteoporosis Society. Bone Density Scans (DXA). Available at: https://theros.org.uk
NHS. Bone Density Scan (DEXA Scan). Available at: https://www.nhs.uk/conditions/dexa-scan/
Shepherd JA, Ng BK, Sommer MJ, Heymsfield SB. Body Composition by DXA. Bone. 2017;104:101–105.
Blake GM, Fogelman I. The role of DXA bone density scans in the diagnosis and treatment of osteoporosis. Postgraduate Medical Journal. 2007;83(982):509–517.
International Atomic Energy Agency (IAEA). Radiation Protection of Patients: Dual-energy X-ray Absorptiometry (DXA). Available at: https://www.iaea.org/resources/rpop
