DEXA vs InBody Singapore: Which Body Composition Test?

InBody is enough for 80% of people, 80% of the time. DEXA is the reference standard for body composition, but the SGD 250 to 500 premium is only worth it for a specific list of cases. The question is not which machine is more accurate. The question is which one answers what you are actually trying to learn.

TL;DR

What InBody actually measures

InBody is a multi-frequency bioelectrical impedance analyser. You stand on a scale, your bare feet on metal electrodes, and you grip a pair of hand electrodes. The machine sends a low-amperage alternating current through your body at several frequencies, measures how much each frequency is resisted, and uses that resistance to estimate fat mass, lean mass, total body water, and a Skeletal Muscle Index. Sixty seconds total. SGD 80 to 180 at any premium personal training studio in Singapore.

What it actually measures is impedance. What you read on the printout is an estimate derived from that impedance via a population-fitted equation. The headline numbers, body fat percent and lean mass, validate well against DEXA in controlled conditions. Antonio and colleagues (2019) compared the InBody 770 against DEXA across a 4-week diet protocol and reported a concordance correlation of 0.88 for fat mass and 0.96 for fat-free mass. McLester and colleagues (2020) tested three InBody models in healthy adults and reported intraclass correlation coefficients above 0.98 for body fat percent, fat mass, and fat-free mass on test-retest.

The catch is real-world conditions. InBody readings are sensitive to hydration, recent meals, and recent training. Stand on it dehydrated and you will read higher body fat. Stand on it 30 minutes after a meal and you will read lower lean mass. In studio conditions across hundreds of repeated measurements, the practical day-to-day variation we see at Catalyst is around 1.5 to 2.5 percentage points on body fat percent, which sets the floor for how small a change you can trust between scans.

What DEXA actually measures

DEXA is dual-energy X-ray absorptiometry. You lie flat on a table, an arm passes over your body at two different X-ray energies, and the difference in absorption between the two energies separates lean tissue from fat tissue from bone. The whole-body scan takes about 6 minutes. In Singapore, you book it at a radiology clinic and pay SGD 250 to 500 for a body composition scan that usually also reports bone mineral density.

DEXA is the reference standard, which means most bioimpedance validation studies report their numbers against a DEXA comparator. This is not the same as saying DEXA is perfect. It still depends on operator positioning, scanner calibration, and the device manufacturer's tissue-discrimination algorithms. Hologic, GE Lunar, and Norland DEXA scanners can disagree by 1 to 3 percent on lean mass in the same subject scanned on the same day. The reference standard has its own error band.

The radiation dose is small. A whole-body DEXA scan delivers roughly 0.001 to 0.003 millisievert, less than one day of natural background radiation in Singapore and roughly one-thirtieth of a transatlantic flight. It is among the lowest-dose imaging exams in clinical use.

Four numbers both tests give you, and the one only DEXA delivers

Both InBody and DEXA report total body fat percent, total lean mass, a Skeletal Muscle Index (lean mass per unit height squared), and an estimate of visceral adipose tissue. For ordinary tracking these four numbers are what you actually use. The InBody and DEXA versions of each correlate strongly enough that month-to-month change tracked on one machine matches month-to-month change tracked on the other, within their respective error bands.

The number only DEXA gives you reliably is regional lean mass. DEXA reports the lean mass in your left arm, right arm, left leg, right leg, and trunk as separate values. This matters in three specific scenarios: rehabilitation after a unilateral injury where you want to track left-versus-right symmetry over months, longitudinal monitoring of appendicular skeletal muscle for sarcopenia diagnostics in adults over 60, and athletes optimising power-to-weight for a sport where leg-specific lean mass distribution matters (cycling, sprinting, single-leg-dominant events). InBody reports segmental impedance, which is not the same thing. The segmental number is a derived estimate, not a direct measurement.

DEXA also gives you bone mineral density at the same scan. That is a separate clinical decision-making input, particularly for post-menopausal women in Singapore where osteoporosis screening is part of HPB-recommended preventive care for adults aged 65 and above.

When InBody is enough

For most adults in Singapore tracking body composition over months and years, InBody is the right tool. The reasons are practical, not technical.

Repeatability beats absolute precision when your goal is to monitor change. If you scan on the same InBody machine at the same time of day, in the same hydration state, every 8 to 12 weeks, the variance between scans is small enough to detect a 1 to 2 kilogram change in lean mass with confidence. A single DEXA scan does not give you change. It gives you a static reference point you might never repeat because of cost.

Most of what you need to know about your body composition is well-served by an InBody scan: are you carrying excess visceral fat, is your lean mass appropriate for your height, is your Skeletal Muscle Index above or below the Asian Working Group for Sarcopenia threshold for your sex, and is your hydration in a normal range. These are the questions InBody answers well. Skeletal Muscle Index together with Waist-to-Height Ratio explains most of the body-composition signal that maps to longevity.

When DEXA is worth the SGD premium

DEXA earns its cost in five situations. First, suspected sarcopenia in adults 60 and above where the AWGS 2019 diagnostic workflow benefits from a reliable Skeletal Muscle Index measurement and the regional lean mass distribution informs treatment priorities. Second, post-surgical rehabilitation where left-versus-right leg lean mass asymmetry tracks the rehabilitation timeline and InBody's segmental estimate is not sensitive enough. Third, athletes optimising power-to-weight where leg-specific lean mass distribution materially changes training prescription. Fourth, establishing a baseline before starting long-term medication that affects body composition: GLP-1 receptor agonists where you want to track lean-mass preservation against the documented muscle-loss risk, hormone replacement therapy, long-term glucocorticoid courses. Fifth, when you are also screening for osteoporosis and one scan can answer two questions.

For anyone outside those five cases, the SGD 250 to 500 premium does not return clinically meaningful information that an InBody scan plus a Jamar grip dynamometer plus a stability assessment would not already give you. The four numbers that actually predict how well you age are not all body-composition numbers.

How we use InBody at Catalyst

InBody is one of four measurements in the Catalyst 4-Pillar Healthspan Assessment we run in our Manulife Tower studio in Singapore's CBD. The other three are cardiorespiratory fitness via a 3-minute step test, grip strength via a Jamar hydraulic dynamometer, and stability via a Y-Balance lower-quarter protocol. The four pillar scores combine into a single Healthspan Score we retest every 16 weeks.

The reason InBody is in our protocol and not DEXA is that we want repeatability across hundreds of clients and dozens of retests per year. Sending every client to a radiology clinic for a DEXA scan every quarter is not realistic. Standing on an InBody for 60 seconds is. The scan is one of four signals we triangulate, not a single number we hand the client and call done. A standalone InBody reading without a strength measurement and a cardiorespiratory measurement is incomplete information about how well a body is ageing.

If a client's InBody scan flags a Skeletal Muscle Index in the AWGS sarcopenia range, or a left-right segmental asymmetry that does not resolve over 8 to 12 weeks of training, we refer out for DEXA. That is the right division of labour. InBody is the screening instrument. DEXA is the diagnostic instrument when the screening flags something. For the broader population context, 32 percent of Singaporeans over 60 already meet sarcopenia criteria, which is why the InBody-then-DEXA pathway exists at all.

Frequently asked questions

Q. How much does an InBody scan cost in Singapore?

At a premium personal training studio or wellness clinic in Singapore, an InBody scan typically costs SGD 80 to 180 as a one-off, often included free as part of a first-session assessment at a longevity-focused studio. The variation comes from whether the scan includes a coach interpreting the result or only a printed sheet. A standalone scan with no interpretation has limited value.

Q. How much does a DEXA scan cost in Singapore?

A whole-body DEXA scan at a Singapore radiology clinic costs SGD 250 to 500. Some clinics bundle DEXA with a bone mineral density read for osteoporosis screening, which is the most cost-efficient way to do both if you are 60 or above. Check whether the report includes regional lean mass distribution; not every radiology centre reports it by default.

Q. Is the DEXA radiation dose safe?

Yes. A whole-body DEXA delivers roughly 0.001 to 0.003 millisievert, less than one day of natural background radiation in Singapore and roughly one-thirtieth of a transatlantic flight. It is among the lowest-dose imaging exams in clinical use and well under the threshold for occupational radiation exposure.

Q. Can I track body composition at home without either machine?

You can buy a consumer-grade bioimpedance scale for SGD 60 to 200 that reports body fat percent. The output drifts more than InBody and absolute accuracy is poor, but change over time within the same device is informative if you weigh yourself under the same conditions each morning. For longevity-focused tracking the more useful at-home measurement is waist-to-height ratio: a tape measure at the navel divided by your standing height. A ratio above 0.5 carries independent metabolic risk regardless of what any body composition scan tells you.

Citations

Antonio, J., Kenyon, M., Ellerbroek, A., Carson, C., Burgess, V., Tyler-Palmer, D., Mike, J., Roberts, J., Angeli, G., & Peacock, C. (2019). Comparison of Dual-Energy X-ray Absorptiometry (DXA) Versus a Multi-Frequency Bioelectrical Impedance (InBody 770) Device for Body Composition Assessment after a 4-Week Hypoenergetic Diet. Journal of Functional Morphology and Kinesiology, 4(2), 23. pmc.ncbi.nlm.nih.gov/articles/PMC7739224

McLester, C. N., Nickerson, B. S., Kliszczewicz, B. M., & McLester, J. R. (2020). Reliability and Agreement of Various InBody Body Composition Analyzers as Compared to Dual-Energy X-Ray Absorptiometry in Healthy Men and Women. Journal of Clinical Densitometry, 23(3), 443-450. sciencedirect.com

Chen, L. K., Woo, J., Assantachai, P., Auyeung, T. W., Chou, M. Y., Iijima, K., Jang, H. C., Kang, L., Kim, M., Kim, S., Kojima, T., Kuzuya, M., Lee, J. S. W., Lee, S. Y., Lee, W. J., Lee, Y., Liang, C. K., Lim, J. Y., Lim, W. S., Peng, L. N., Sugimoto, K., Tanaka, T., Won, C. W., Yamada, M., Zhang, T., Akishita, M., & Arai, H. (2020). Asian Working Group for Sarcopenia: 2019 Consensus Update on Sarcopenia Diagnosis and Treatment. Journal of the American Medical Directors Association, 21(3), 300-307. jamda.com

Pang, B. W. J., Wee, S. L., Lau, L. K., Jabbar, K. A., Seah, W. T., Ng, D. H. M., Tan, Q. L. L., Chen, K. K., Mallya, J. U., & Ng, T. P. (2021). Prevalence and Associated Factors of Sarcopenia in Singaporean Adults: The Yishun Study. Journal of the American Medical Directors Association, 22(4), 885.e1-885.e10. jamda.com