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What Is a DEXA Body Composition Scan? Everything You Need to Know

  • Mar 20
  • 3 min read

Updated: Apr 9

If you have ever wondered exactly how much of your body is fat, muscle, and bone, a DEXA body composition scan gives you the most accurate answer available. Unlike bathroom scales, skin-fold calipers, or bioelectrical impedance devices, DEXA provides a clinical-grade, region-by-region breakdown of your body in a single 10-minute appointment.



How DEXA Works


DEXA stands for Dual-Energy X-ray Absorptiometry. The scanner passes two low-dose X-ray beams through your body at different energy levels. Because fat, lean tissue, and bone each absorb X-rays differently, the machine calculates the exact mass of each tissue type across every region of your body - arms, legs, trunk, and android (belly) area.

The radiation dose is extremely low. Roughly one-tenth of a standard chest X-ray. The scan is painless, non-invasive, and takes about 10 minutes while you lie still on an open table.


What Your DEXA Report Tells You


A DEXA report from Precision Body Lab includes:

  • Total body fat percentage — your overall fat mass relative to total body weight.

  • Regional fat distribution — exactly how fat is distributed across your arms, legs, trunk, and android region.

  • Visceral adipose tissue (VAT) — the dangerous fat stored around your internal organs, linked to cardiovascular disease and metabolic syndrome.

  • Lean muscle mass — total and regional muscle, including left-vs-right comparisons to detect imbalances.

  • Bone mineral density — a whole-body bone density reading that can flag early signs of osteopenia or osteoporosis.

  • Appendicular lean mass index (ALMI) — your limb muscle mass relative to height, used clinically to screen for sarcopenia (age-related muscle loss).


DEXA vs Other Methods: Why Accuracy Matters


Bathroom scales tell you total weight. Bioelectrical impedance (BIA) devices (including smart scales and handheld analysers) estimate body fat by sending an electrical current through your body. The problem is BIA results shift significantly based on hydration, recent meals, exercise, and even time of day. Studies consistently show BIA can be off by 3-15% on body fat readings compared to DEXA.


Skin-fold calipers are operator-dependent and only measure subcutaneous fat at a few sites. They miss visceral fat entirely and cannot measure bone density or regional muscle distribution.


DEXA is widely regarded as the gold standard for body composition measurement in both clinical and research settings. It is the only widely accessible method that simultaneously measures fat, lean tissue, and bone with regional precision.


Who Should Get a DEXA Scan?


A DEXA body composition scan is valuable for anyone who wants objective data about their body. Common reasons our clients in Miranda book a scan include:

  • Starting a weight loss or fitness program and wanting a precise baseline.

  • Tracking fat loss vs muscle loss during dieting - the scale alone cannot distinguish between the two.

  • Monitoring body recomposition (losing fat while building muscle), where total weight may not change at all.

  • Assessing visceral fat levels for metabolic health screening.

  • Checking bone density, particularly for women over 50 or anyone with osteoporosis risk factors.

  • Athletes and coaches wanting regional muscle data to identify imbalances or track training progress.


How to Prepare for Your Scan


To get the most consistent results:

  • Fast for at least 2 hours before the scan. Morning appointments after an overnight fast produce the most reliable readings.

  • Stay normally hydrated (do not over-hydrate or dehydrate).

  • Avoid heavy exercise in the 24 hours before your scan, as muscle inflammation and glycogen shifts can affect readings.

  • Wear lightweight clothing without metal (zippers, underwires, buckles). We have gowns available if needed.

  • Skip calcium supplements for 24 hours prior.

  • Empty your bladder before the scan.


How Often Should You Scan?


For clients actively working on changing their body composition, we recommend scanning every 8 to 12 weeks. This gives your body enough time to make measurable changes while keeping you accountable. Your follow-up scan is compared directly to your baseline, so you can see exactly where fat has decreased, where muscle has increased, and whether your visceral fat has improved.


Precision Body Lab is located at Suite 4, 31-41 Kiora Rd, Miranda NSW 2228. Book your DEXA body composition scan today and replace guesswork with precision.


Ready to see your own results?


Book a DEXA body composition scan at Precision Body Lab - Sydney's dedicated DEXA clinic in Miranda. Trusted by 1,000+ clients, rated 5 stars on Google.



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