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Body measures and lab tests

DEXA scan

A DEXA (or DXA) scan uses very low-dose x-rays to measure bone density and, on many machines, fat mass and lean mass in different parts of the body.

Clinician review pending Updated Body measures and lab tests
DefinitionA DEXA (or DXA) scan uses very low-dose x-rays to measure bone density and, on many machines, fat mass and lean mass in different parts of the body.

What it means

DEXA stands for dual-energy x-ray absorptiometry. It is best known as the standard test for osteoporosis, where it measures bone mineral density at the hip and spine. Many scanners can also run a whole-body scan that splits weight into fat, lean tissue and bone.

The CDC describes DEXA as a precise way to measure body composition, but notes it is expensive and not widely available. Most major GLP-1 trials that reported fat and lean mass changes used DEXA in a subset of participants.

The scan takes several minutes while you lie still on a table. Radiation exposure is very low, but the test is not recommended during pregnancy.

Results vary somewhat between machines and with hydration, so repeat scans are most useful on the same device under similar conditions. Insurance usually covers DEXA for bone health, not for body composition alone.

Why it matters

DEXA is how researchers measured muscle and fat loss on GLP-1 medicines, so it anchors the lean-mass discussion.

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Related terms

Body compositionBody fat percentageLean body massHow to measure body fatKeeping muscle while you lose weight

Sources

  1. MedlinePlus: Bone density scan
  2. CDC: About body mass index (BMI)

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