DEXA Scan
A low-radiation imaging test that precisely measures bone density, body fat percentage, and lean muscle mass to guide weight management.
Plain English
Patient-Friendly Explanation
A DEXA scan (dual-energy X-ray absorptiometry) is a low-dose X-ray that measures body composition precisely — how much of you is fat, lean tissue and bone, including in specific regions like arms, legs and trunk. It is the reference standard used in medical research, which is why it is trusted for tracking. The scan is quick (about 10–15 minutes), painless, requires no injections or dye, and involves a very small radiation dose — less than a chest X-ray, though still not used in pregnancy. It reports fat mass and percentage, lean mass (with a skeletal muscle index), bone mineral density, and visceral fat estimates — the last being important because visceral fat drives metabolic risk. DEXA is most useful when precision matters: diagnosing sarcopenic obesity, distinguishing muscle from fat loss during treatment, assessing bone health (it is also the standard test for osteoporosis), or when clinic BIA readings need confirmation. For everyday progress tracking, an InBody analysis is usually enough; DEXA is the precision tool when the clinical question demands it.
Medical
Clinical Definition
Dual-energy X-ray absorptiometry (DEXA, also DXA) uses two X-ray energies to separate tissue into fat, lean and bone mineral compartments by differential attenuation, providing criterion-standard body composition with regional analysis (trunk, limbs, android/gynoid distribution) and visceral adipose tissue estimation. Effective radiation dose is low (~1–10 μSv, comparable to a few days' background exposure). Applications include body-composition assessment where BIA is confounded (extreme adiposity, fluid shifts, athletes), diagnosis of sarcopenia via appendicular lean mass indices, longitudinal monitoring of lean-mass preservation during pharmacotherapy-assisted weight loss, android-gynoid ratio and visceral fat evaluation for cardiometabolic risk stratification, and bone mineral density assessment for osteoporosis. Limitations include cost, limited availability, dependence on operator and software version for comparability across centres, and avoidance in pregnancy. When serial tracking is the goal, consistency at the same centre matters more than the absolute values.
Key Insight
Why It Matters
DEXA answers the question that vague measurements cannot: exactly what did I lose — fat, muscle or bone? In weight-management practice, its value peaks in three scenarios: distinguishing true fat loss from lean-mass loss during rapid weight reduction, detecting sarcopenic obesity (the highest-risk pattern, especially relevant as populations age), and assessing bone density in patients whose weight loss or medical history raises fracture concerns. For most patients, the practical approach is InBody at clinic reviews for progress, DEXA when the clinical picture is ambiguous or the stakes are high.
Sources
Reviewed against standard medical references.
Medically reviewed by
Family Physician & Registered Acupuncturist, Accord Medical Clinic. MBBS (NUS), Graduate Diploma in Family Medicine (NUS), Graduate Diploma in Acupuncture (Singapore College of TCM).
Last reviewed: August 2026
This page is general health education, not medical advice. Whether any treatment is appropriate for you is a decision made in consultation after assessment.
