What You Need to Know about a Dexa Scan

 

A Dual-Energy X-ray Absorptiometry (DEXA) scan uses low-dose X-ray beams at two different energy levels to differentiate between bone tissue and soft tissue, giving a detailed picture of bone density, lean body mass, and fat mass.

It is a painless, non-invasive procedure lasting only a few minutes.

Although other methods for measuring body composition can be useful in certain settings, DEXA is recognised as the ‘gold standard’ due to its ability to measure more compartments and do so to a more accurate degree.

The comprehensive data it provides then enables clinicians to develop a far more personalised health plan for individuals.

 

What It Measures

• The DEXA scan provides a detailed report that includes:
  • Total body fat percentage
  • Total lean mass
  • Bone mineral density
  • Regional analysis – fat mass, lean mass, and bone density of the following areas:

• • • Left Arm
    • Right Arm
    • Torso
    • Abdomen (Android)
    • Hips (Gynoid)
    • Left Leg
    • Leg(e.g., arms, legs, trunk), which can show how

This information is also compared against normative data – showing where you are in relation to the average of a certain population dataset.

 

Fat Mass 

The scan will provide your total fat mass and body fat percentage.

One of the most significant advantages of DEXA scans is their ability to differentiate between visceral (around organs) and subcutaneous (under the skin) fat.

This distinction is crucial because visceral fat is closely linked to various health risks, including heart disease, diabetes, and metabolic syndrome.

By identifying the levels of visceral fat, clinicians can prioritise interventions to reduce the risk of certain chronic diseases through lifestyle changes.

 

Lean Mass

Similarly, the scan will show you your total lean muscle mass and compartmentalise the results into each body part.

These metrics can provide information about potential asymmetries or muscle loss in specific regions post-injury.

The data can be a useful way to inform further strategies or collect feedback on how specific training and dietary interventions are impacting muscle mass.

Bone Mineral Density (BMD)

BMD refers to the amount of bone mineral (calcium and other minerals) present in a specific volume of bone.

It is a key indicator of bone strength and health and is therefore essential for assessing the risk of osteoporosis and fractures.

The scan typically focuses on high-risk areas for osteoporosis, such as the lumbar spine, femoral neck, and hip.

This data can prompt dietary changes, such as increasing intake of calcium-rich foods and vitamin D, to support bone health.

Additionally, the scan results can inform the recommendation of resistance training, and potential signs of REDs, a condition often seen in athletes that can lead to decreased athletic performance and increased injury risk.

Readings and Interpretation:

T-score: The primary outcome for assessing BMD from a DEXA scan is the T-score, which compares an individual’s bone density to that of a healthy young adult of the same sex.

A T-score of -1.0 or above is considered normal, between -1.0 and -2.5 indicates low bone mass (osteopenia), and -2.5 or below is diagnosed as osteoporosis.

Z-score: This score compares an individual’s BMD to what’s expected for someone of the same age, sex, weight, and ethnic or racial background.

Z-scores are particularly useful for assessing bone density in children, adolescents, premenopausal women, and men under 50.

 

Frequency

The frequency of scans should be tailored to the individual needs, goals, and specific circumstances.

For body composition changes, getting a scan every 3-4 months may be helpful to gain insight into whether certain training and nutrition strategies are effectively supporting their goals.

For bone mineral density, scans may be performed less frequently, with the general guidelines being 1-2 years after the initial unless you have a specific focus on this.

It is also important that follow-up scans are performed on the same machine as different DEXA machines can have slight variations in calibration.

How to Prepare for the Scan

Choose loose, comfortable clothing without metal zippers, buttons, or belts, as metal can interfere with the scan results. This includes other metal-containing items such as jewellery and watches.

Leave >12 hours between strenuous exercise and scanning.

No eating or drinking the morning of the scan.

No alcohol consumption <12 hours before testing.

It is also advised to go to the bathroom and empty your bladder beforehand.

Conclusion

DEXA is considered the “gold standard” for body composition analysis and bone mineral density assessment. Hopefully, this post covered a lot of things you might be wondering, but if you have any specific questions, please don’t hesitate to reach out and touch base with us via the contact section of this website.