Body shape indices (BAI, ABSI, Conicity Index, SMM/VFA)
Body shape indices are supplementary research measures that relate body circumferences to height, weight or muscle mass in various ways.
Short answer
These four indices are supplementary research values. Deciding from them makes little sense — waist circumference, the waist-height ratio and Visceral Fat Area are clearer and better supported.
What the value represents
Four values on the result sheet share one thing: they try to describe body shape differently from BMI. They are the Body Adiposity Index (BAI), A Body Shape Index (ABSI), the Conicity Index, and the ratio of skeletal muscle mass to visceral fat area.
They share one page because none of them is a headline measure. The manual lists them among research parameters and they serve as a companion, not as a basis for decisions.
All four rest on estimated inputs: circumferences derived from body composition, and for the last one also an estimate of visceral fat area.
For ordinary use, waist circumference, the waist-height ratio and Visceral Fat Area are clearer and better supported.
- BAI (Body Adiposity Index) – an estimate of adiposity from hip circumference and height. Unlike BMI it does not use weight.
- ABSI (A Body Shape Index) – waist circumference assessed in the context of height and BMI, that is the waist related to body size.
- Conicity Index – waist circumference related to height and weight; it describes how concentrated volume is in the trunk.
- SMM to visceral fat area – skeletal muscle mass divided by the estimated visceral fat area; it compares metabolically active muscle with the riskier fat depot.
- None of them represents the amount of fat in kilograms or a direct measurement of it.
How the value is produced
- All four are calculated values.
- BAI builds, per the manual, on hip circumference and height, with a constant subtracted from the result. ABSI combines waist circumference, height and BMI. The Conicity Index builds on waist circumference, height and weight.
- On InBody 970 the input circumferences are estimates from body composition rather than tape measurements without the Yscope module.
- The SMM to visceral fat area ratio divides an estimated muscle mass by an estimated visceral fat area, so it combines the uncertainty of both estimates.
- For that ratio the manual gives the unit kg/m², even though dividing kilograms by cm² yields a different unit. The source is inconsistent here, so treat the unit with caution.
How to read the current value
- The thresholds given in the manual: BAI above 26.9, ABSI 0.076 or above, Conicity Index above 1.25. The manual labels these thresholds for abdominal obesity.
- Treat them as orientation points the manufacturer took from research literature, not as diagnostic criteria. The manual does not state which studies they come from.
- For the SMM to visceral fat area ratio we give no threshold. The manual claims that a higher ratio means sarcopenic obesity, which contradicts the meaning of the ratio — more muscle relative to visceral fat ought to be more favourable. Until another source confirms it, read this value only as a trend.
- The example values for these parameters in the manual are moreover visibly corrupted (a BAI of 2.81 next to a threshold of 26.9, for instance), so not even a typical range can be inferred from them.
How to read change over time
- All the indices move with circumferences, height and weight. Because height is stable, they change in practice with circumferences and weight.
- Follow the inputs instead: waist circumference, hip circumference, weight, muscle mass and visceral fat area. The indices are only a restatement of them.
- The SMM to visceral fat area ratio can shift from two sides — a rise in muscle mass or a fall in visceral fat. Without looking at both components you do not know what happened.
General principles: how to read change between measurements →
What to read it with
- Waist circumference and the waist-height ratio – more direct indicators of central fat.
- The waist-hip ratio – the most common indicator of body shape.
- Visceral Fat Area – an input to the last of the indices.
- Skeletal Muscle Mass – the other input to that same ratio.
- BMI and Percent Body Fat – the basic values these indices complement.
Common misunderstandings
- They are not a refinement of BMI. They are different views with their own limits, not more accurate measurements.
- BAI is not percent body fat, even though it tries to estimate adiposity.
- The thresholds are not diagnostic criteria. InBody does not diagnose obesity or metabolic disease.
- The indices rest on estimated circumferences, so they cannot be more accurate than those estimates.
- The SMM to visceral fat area ratio is not an indicator of sarcopenia. Expert criteria for low muscle mass work with muscle strength and a muscle mass index.
What can affect the result short term
- Everything that shifts the body composition estimate and the circumferences derived from it: hydration, food and drink, bloating, training, time of day.
- The accuracy of the entered height, because it enters most of these indices.
- The menstrual cycle.
- The presence of the Yscope module, which turns the waist circumference estimate into a measurement.
What to do next
- For ordinary decisions use waist circumference, the waist-height ratio and Visceral Fat Area. Keep these indices as supplementary information.
- If one of them catches your attention, look at its inputs first — they usually explain the whole change.
- Do not compare values between devices and online calculators; both the calculation method and the quality of the inputs differ.
What the value does not determine
- They do not diagnose obesity or metabolic disease.
- The input circumferences are an estimate rather than a measurement without the Yscope module.
- For the SMM to visceral fat area ratio the threshold is unusable, because the source contradicts itself.
- Both the example values and the stated unit of that ratio are inconsistent in the manual.
- The manual does not state which studies the thresholds come from.
On terminology
- Abbreviations: BAI = Body Adiposity Index, ABSI = A Body Shape Index, CI = Conicity Index. The last of the values appears in the data as the ratio of SMM to visceral fat area.
- Abdominal obesity in the manual is a description of fat distribution against a threshold value, not a medical diagnosis.
In more depth, with sourcesIn more depth: what shape indices add and where their limits lieExpand the detailed explanation
All three shape indices arose from the same motivation: BMI does not distinguish where mass is stored. BAI therefore drops weight and works with hip circumference and height, ABSI places waist circumference in the context of height and BMI, and the Conicity Index relates the waist to height and weight. These are different normalisations of similar information, so they correlate strongly with each other and with circumference-based measures. The independent information added is therefore smaller than four separate numbers would suggest.
The inputs on InBody 970 are estimated circumferences without the Yscope module, which the repository reference classes among estimated values. The manufacturer internal validation study against DEXA covers fat free mass, fat mass and segmental lean mass — not circumferences and not visceral fat area. These indices therefore sit two derivations away from measured data, and their absolute values carry a corresponding spread.
For the ratio of skeletal muscle mass to visceral fat area, a contradiction in the source is added to the two estimates. The manual gives threshold values with wording under which a higher ratio means sarcopenic obesity, which contradicts the meaning of the ratio: more muscle per unit of visceral fat is logically the more favourable state. The repository reference therefore recommends either verifying the claim against another source or not using the parameter. We present it as a concept, but without a threshold.
The practical consequence is the same for all four: on one device and in one person they behave as monotonic restatements of their inputs. Anyone who wants to know what changed should read waist circumference, hip circumference, weight, muscle mass and visceral fat area directly. The WHO expert report on waist circumference and waist-hip ratio sticks to simple anthropometric indicators for the same reason.
Sources
- InBody 970 Result Sheet Interpretation (ENG_A_211104) — InBody Co., Ltd.
- Validation of InBody 970 (BWA) against DEXA — InBody Co., Ltd.
- Waist circumference and waist–hip ratio: report of a WHO expert consultation — World Health Organization
On this page
Related values
Related articles
Where to find it
The Visceral Fat Analysis, circumferences and basal metabolic rate.
- Reviewed by
- MojeInBody content team
- Date
An InBody measurement is not a diagnostic tool. Results do not determine health status and do not replace a medical examination.
FAQ
Frequently asked questions
Answers to what people ask most often about this value.
Which of these indices should I follow?
None of them in preference. For following central fat, waist circumference and the waist-height ratio are more practical; the shape indices build on them anyway and merely restate them.
Why do you give no threshold for the SMM to visceral fat area ratio?
Because the source contradicts itself on this point. The manual gives thresholds with wording under which a higher ratio means sarcopenic obesity, although a higher proportion of muscle relative to visceral fat ought to be more favourable. Until another source confirms it, we give no specific number.
Is BAI more accurate than BMI?
It is not a more accurate measurement, only a different calculation from different inputs. BAI works with hip circumference and height, and on InBody the circumference is itself estimated — so its own uncertainty is if anything higher, not lower.
Explanations make the most sense alongside your own trend.
The public guide is open to everyone. The client portal adds your own value, history and the context of a specific measurement.