Measurement · not graded
Bioelectrical Impedance Body Composition (BIA)
What the evidence looks at: agreement with DXA and four-compartment reference methods.
At a glance
A body fat scale or standing analyzer sends a tiny, harmless current through the body to estimate fat and muscle. This page asks how close its numbers come to lab methods. In studies, one common machine gave very steady readings but was off in one direction, counting more muscle and less fat than a DEXA scan. It measures, and it does not treat.
What the studies looked at: Agreement with DXA and four-compartment reference methods
Why this letter
Ungraded: a BIA analyzer is a measurement instrument, not an intervention. The A-D scale grades treatment efficacy; no trial randomizes people to being measured.
Standing multi-frequency BIA (InBody 770) agreed well with a four-compartment model for fat mass and fat-free mass in normal-weight young adults, with larger error for percent body fat, especially in women (Brewer 2021, PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 33752260). Against DXA in 795 active-duty Marines, the InBody 770 was highly precise but systematically overestimated fat-free mass by about 2.7 kg and underestimated percent body fat by about 3.4 points (Potter 2022, PMID 36619314). Useful for tracking change in the same person on the same device; not interchangeable with DXA values. The validation evidence is for the professional analyzer, not for home scales.
Evidence notes: not independently replicated The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away.
Last reviewed: September 2026
Dose, form and timing
Same device, same time of day, fasted and before exercise, for every reading. Readings are comparable with each other, not with a DXA report.
Products carry no letter. The letter belongs to the therapy as the trials studied it, and no trial tested these products unless the entry says so. Listed alphabetically; payment does not affect order.
Standing multi-frequency bioelectrical impedance analyzer reporting fat mass, fat-free mass, segmental lean mass and body water. Validated against DXA and a four-compartment model, with a known systematic offset.
Professional standing multi-frequency analyzer, the model used in the validation studies. InBody’s home scales use a different design and are not covered by those studies.
Grade history
How this letter has changedLatest: No. 38 · September 2026 · Added.
New measurement entry, ungraded by design because an analyzer is an instrument, not an intervention. The InBody 770 agreed well with a four-compartment model and with DXA for tracking, with a known systematic offset against DXA: Brewer et al. (Clin Physiol Funct Imaging 2021; PMID 33752260) and Potter et al. (BMJ Nutr Prev Health 2022; PMID 36619314).PMID 33752260 PMID 36619314
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Sources
Primary evidenceTwo papers, each linked to its PubMed record.
Brewer et al. (Clin Physiol Funct Imaging, 2021; PMID 33752260): 82 normal-weight young adults, InBody 770 against a four-compartment criterion, total error 2.4 kg for fat mass and fat-free mass and 4.2 points for percent fat. Potter et al. (BMJ Nutr Prev Health, 2022; PMID 36619314): 795 US Marines, InBody 770 against DXA, r squared 0.96 for percent fat, with a systematic offset. Ungraded: measurement validity, not a treatment claim.
Disclosure
Educational use only · Not medical advice · EBL grades published human evidence and does not recommend treatment.
Evidence Based Longevity, Inc. is owner-operated and edited by Arnold Sandlow, D.C., a California-licensed chiropractor. Evidence Based Longevity publishes in English only · Machine translations are not produced or reviewed by EBL for accuracy
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