Published on 02 April 2026
The Body Mass Index (BMI) is often used for assessing and categorising weight, but does it reveal the full story if you are at risk of developing osteoporosis or gaining too much weight?
Interest is increasing in an alternative to the BMI approach which uses low dose X-rays to calculate the density of your bones and to measure your muscle and fat tissue.
Who may need a DEXA scan?
The scan is ideal for quickly and accurately diagnosing or assessing your risk of osteoporosis and helping to assess the risk of bone fracture in the long term.
It can help you make decisions about changing your diet and the level of exercise you do, and it can indicate what treatments might be appropriate for you.
A DEXA scan may be useful for patients who have, or are at risk of developing, obesity, anorexia nervosa, cystic fibrosis, wasting syndrome, and chronic renal failure.
Furthermore, a DEXA scan can be recommended for athletes who would benefit from a greater understanding of how they shape up in terms of body fat, lean mass and muscle density.
How does the DEXA scan work?
During the scan a type of X-ray called dual energy X-ray absorptiometry is passed through your body. Detectors in the scanner measure how much radiation passes through the bone and computerised data is generated.
Your bone density measurements will be compared to those judged to be ideal.
Does your bone density change?
Yes, it does alter. Up to your mid-30s it is likely your bones will be at their most robust. After this age it is inevitable that bone strength declines. If you develop osteoporosis your bones will become more fragile than normal.
How is the scan conducted?
You will lie on your back on a special X-ray table, and a scanning arm will move over your body. The scan usually takes 10 to 20 minutes. While no special preparations are needed, you will have to remove any items of clothing which has metal components such as zips. Also, you will have to mention any metalwork implanted anywhere in your body.
How safe is the new approach?
The DEXA scan is very safe as the X-ray dose is a much lower level of radiation than is used compared to the amount employed in a standard X-ray.
Despite being very safe, the scan is not recommended for women who are pregnant. Also, the scan is not suitable for women who have had a baby in the past 12 months and for anyone under the age of 20.
How to access a DEXA scan at Benenden Hospital
Worried about fragile, weak bones or wanting to gain a better picture of your fat to muscle tissue ratio?
To arrange a DEXA scan, you’ll need a referral from a healthcare professional. This could be your own GP, through our Private GP service or from a consultant or osteopath. Visit our DEXA scan page to learn more.