If you’ve used both an InBody scale at your gym and gotten a DEXA scan, you’ve probably seen them disagree by 3–8 percentage points on body fat. The question everyone asks: which one is right? The short answer is DEXA — but the longer answer is more nuanced. Here’s the honest DEXA vs InBody comparison.

How each technology works

InBody (BIA)

You stand on the scale, hold the hand grips, and a small electrical current passes through your body via 8 electrodes (feet + hands). The machine measures resistance at multiple frequencies. Lean tissue (water, muscle) conducts well; fat resists. Algorithms estimate body composition from the resistance pattern.

DEXA

You lie on a padded table while a scanning arm passes over you. Two low-energy X-ray beams measure tissue attenuation. Fat, lean tissue, and bone all attenuate differently — the scanner calculates each from the attenuation pattern. The measurement is direct, not inferred.

Where they differ

Dimension	InBody	DEXA
Accuracy (CV)	±3–5%	±1.0–1.5%
Time	~60 seconds	7 minutes
Cost	Free at most gyms	$29.99 (BodyStats) – $300+
Regional breakdown	Yes (8 electrodes)	Yes (5 regions, more granular)
Visceral fat (VAT)	Estimated	Measured
Bone density	No	Yes (T- and Z-scores)
Hydration sensitivity	High	Low
Repeatability day-to-day	Moderate	High

Why InBody readings drift

InBody’s biggest weakness is hydration sensitivity. A 2% body water shift can move the body fat reading by 2–3 percentage points. So:

• Drink a litre of water before stepping on → reading drops.
• Skip water for 8 hours → reading climbs.
• Test post-workout vs pre-workout → different readings.
• Test in the morning vs evening → different readings.

This means an InBody reading from a Monday morning often disagrees with a Wednesday evening reading on the same person, even if no actual body composition change has happened.

If you’re tracking a 12-week cut and your InBody readings vary 4% from hydration alone, you can’t tell if you actually lost fat. The signal disappears in the noise.

Where DEXA wins

Trackable change

Because DEXA’s day-to-day variability is under 1.5%, a real 1–2% body fat change across an 8–12 week training block is visible. With InBody, that change can be lost in measurement noise.

Visceral fat

InBody estimates VAT from segmental impedance. DEXA measures the deep abdominal fat directly. For metabolic-health-oriented clients, DEXA’s VAT number is meaningfully more reliable.

Bone density

InBody doesn’t measure bone density at all. DEXA gives you a full bone density assessment alongside body composition.

Regional precision

Both give regional breakdowns, but DEXA’s are more granular and more accurate. Particularly important if you’re tracking asymmetry.

Where InBody wins

Daily access

If your gym has an InBody and you can step on it any time, that’s hard to beat for trend tracking. Once-a-week InBody readings can show a directional trend even if absolute numbers are wrong.

Cost (often free)

Most major gyms include InBody scans free for members. If you’re testing 3+ times a month, the cost difference adds up.

Speed

60 seconds vs 7 minutes plus appointment booking. Convenient if you want a quick check.

The right combination

1. Daily: bathroom scale weight only.
2. Weekly: InBody at your gym (consistent time of day, consistent hydration).
3. Quarterly: DEXA scan to confirm what InBody and your scale were actually measuring.

That cadence gives you tight feedback without trusting any single tool too far. The Vancouver methods comparison covers BodPod and other alternatives if you want a fuller picture.

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