ABSI (A Body Shape Index) is a measure devised in 2012 by Nir and Jesse Krakauer to assess the risk linked specifically to body shape rather than weight alone. It takes waist circumference and "cleans" it of the influence of BMI and height.
The value of ABSI is that it predicts mortality independently of BMI: two people with the same BMI but different waists get a different ABSI and a different risk. A high index reflects an excess of visceral fat.
Reference ranges
ABSI is rarely interpreted by its absolute number — it is converted to a z-score relative to the mean values for one's sex and age. Approximate absolute thresholds:
| Units | m / kg^(2/3) (usually ≈ 0.07–0.09) |
| Increased risk | ABSI > 0.083 |
| Doubling of relative risk | ABSI ≈ 0.091 |
| z-score around 0 | average risk for sex and age |
| z-score > +1 | body shape "riskier" than average |
What an elevated level means
A high ABSI (a positive z-score, a value above average for one's sex and age) means a relatively wide waist for a given weight and height — a marker of central obesity. In studies mortality rose almost exponentially with increasing ABSI, and independently of BMI, smoking, blood pressure and diabetes.
What a low level means
An ABSI around or below average (z-score ≤ 0) is a body shape with a relatively narrow waist and a more favorable risk profile. Importantly, a low ABSI does not cancel out other factors and does not mean that weight and metabolism are normal.
How the test is done
Formula: ABSI = WC / (BMI2/3 × Height1/2), where waist circumference (WC) and height are taken in meters and BMI in kg/m². The resulting number is compared with the mean for one's sex and age and expressed as a z-score: ABSI-z = (ABSI − mean) / standard deviation.
What affects the value
- Accuracy of the waist measurement directly affects the index.
- Age and sex — required to calculate the z-score and interpret it correctly.
- Ethnicity: population means differ.
Calculate using this marker
Calculators where ABSI (A Body Shape Index) is used directly:
Frequently asked questions
How is ABSI better than BMI?
ABSI is almost independent of height, weight and BMI and reflects body shape itself — fat distribution. So it adds a mortality prediction over and above BMI, but it is used as a complement, not a replacement.
What ABSI is normal?
There is no single "norm": the measure is assessed via a z-score relative to one's sex and age. A value near the mean (z ≈ 0) is average risk; noticeably above the mean is increased.
Related terms
Sources
- Wikipedia — A Body Shape Index
- Krakauer & Krakauer, 2012 (PLOS ONE) — A New Body Shape Index Predicts Mortality Hazard Independently of BMI