Understanding ABSI: Beyond BMI for Health Risk Assessment
Why waist circumference matters and what A Body Shape Index actually tells you about health risk.
Key Takeaways
- ABSI (A Body Shape Index) combines waist circumference with BMI and height to better assess health risks.
- Research shows ABSI is a stronger predictor of mortality risk than BMI or waist circumference alone.
- ABSI specifically targets the health risks associated with central obesity (excess abdominal fat).
- People with normal BMI but high ABSI may still have significant health risks that BMI alone doesn't capture.
- Using multiple metrics (BMI, ABSI, body fat percentage) together gives a fuller picture than any single number.
What is ABSI?
A Body Shape Index (ABSI) is a metric developed in 2012 by researchers Nir Y. Krakauer and Jesse C. Krakauer. It incorporates waist circumference as a measure of central obesity, addressing a gap that BMI leaves open.
The formula for ABSI is:
ABSI = WC / (BMI2/3 × Height1/2)
Where WC is waist circumference in meters, BMI is in kg/m², and height is in meters
The formula measures how much your waist circumference deviates from what would be expected given your height and weight. A higher ABSI means you carry more weight around your waist than expected for someone with your BMI.
Why ABSI Matters: The Limitations of BMI
BMI has been the standard weight-health metric for decades, but its limitations are well documented:
- It doesn't distinguish between fat and muscle mass
- It doesn't account for fat distribution
- It doesn't consider age, sex, or ethnicity
The second limitation matters most here. Where you carry your fat may matter as much as how much fat you have. Abdominal fat, especially the visceral fat surrounding your organs, is more strongly linked to health risks than fat stored elsewhere.
ABSI addresses this by incorporating waist circumference relative to BMI and height, targeting the health risks tied to central obesity specifically.
Case Study: Normal BMI but High ABSI
Consider two individuals with the same BMI of 24 (within the "normal" range):
- Person A: Has a relatively small waist and carries more weight in their hips and thighs (pear-shaped)
- Person B: Has a larger waist and carries more weight around their abdomen (apple-shaped)
According to BMI alone, both individuals would be classified as having the same health risk. However, Person B would have a higher ABSI, reflecting their increased abdominal fat and potentially higher health risk despite having a "normal" BMI.
BMI would flag both as equal risk. ABSI would not.
The Science Behind ABSI
The original ABSI study, published in PLOS ONE in 2012, analyzed data from over 14,000 adults in the National Health and Nutrition Examination Survey (NHANES) 1999-2004. The researchers found that:
- ABSI was strongly associated with mortality risk, independent of other predictors
- The association between ABSI and mortality was consistent across age, sex, ethnicity, and weight categories
- People with high ABSI had an increased risk of death even if they had a normal BMI
Follow-up studies have confirmed these findings. ABSI appears most useful for identifying health risks in people whose BMI falls in the normal or overweight range.
A 2020 meta-analysis published in the journal Obesity Reviews found that ABSI was a better predictor of all-cause mortality than BMI, waist circumference, and waist-to-height ratio.
Understanding Your ABSI Z-Score
When you calculate your ABSI using our ABSI Calculator, the result is typically expressed as a z-score, which compares your value to the average for your age and sex:
- A z-score of 0 means your ABSI is exactly average
- A positive z-score means your ABSI is above average (higher risk)
- A negative z-score means your ABSI is below average (lower risk)
The further your z-score is from zero, the more your ABSI deviates from the average. Research suggests that each standard deviation increase in ABSI (approximately a z-score increase of 1) is associated with a 33% higher risk of premature death.
ABSI Risk Categories
| Z-Score Range | Risk Category | Interpretation |
|---|---|---|
| Below -0.868 | Very Low Risk | Significantly below average ABSI |
| -0.868 to -0.272 | Low Risk | Below average ABSI |
| -0.272 to 0.229 | Average Risk | Average ABSI |
| 0.229 to 0.798 | High Risk | Above average ABSI |
| Above 0.798 | Very High Risk | Significantly above average ABSI |
Improving Your ABSI
If your ABSI is high, the main lever is reducing waist circumference. A few approaches that work:
- Core training: Spot reduction is not possible, but exercises like planks and Russian twists strengthen abdominal muscles and improve posture.
- Cardiovascular exercise: Walking, running, swimming, or cycling all reduce overall body fat, including abdominal fat.
- Strength training: Building muscle mass improves body composition and metabolic health.
- Healthy diet: Focus on whole foods, lean proteins, fruits, vegetables, and whole grains while limiting processed foods, added sugars, and excessive alcohol.
- Stress management: Chronic stress contributes to abdominal fat accumulation. Meditation, yoga, or even regular deep breathing can help.
- Adequate sleep: Poor sleep is linked to increased abdominal fat. Aim for 7-9 hours per night.
ABSI vs. Other Body Composition Metrics
ABSI is one of several body composition metrics. Here is how they compare:
- BMI (Body Mass Index): Measures overall weight relative to height, but doesn't distinguish between fat and muscle or consider fat distribution.
- Waist Circumference: Measures abdominal fat directly, but doesn't account for overall body size.
- Waist-to-Hip Ratio (WHR): Compares waist and hip circumferences to assess fat distribution pattern.
- ABSI (A Body Shape Index): Combines waist circumference with height and weight to specifically assess the health risk of central obesity.
- Body Fat Percentage: Measures the actual proportion of fat in your body, regardless of where it's distributed.
No single metric covers everything. If you want a fuller picture of your body composition and health risks, check your BMI, ABSI, and body fat percentage together rather than relying on any one number.
Conclusion
ABSI accounts for waist circumference relative to BMI and height, catching health risks that BMI misses, particularly in people who carry excess fat around their midsection.
No single metric captures every aspect of health. ABSI works best alongside BMI and body fat percentage, and in conversation with a doctor who can interpret your numbers in context.
Use our ABSI Calculator to find your ABSI and z-score.
References
- Krakauer NY, Krakauer JC. A new body shape index predicts mortality hazard independently of body mass index. PLoS ONE. 2012;7(7):e39504.
- Ji M, Zhang S, An R. Effectiveness of A Body Shape Index (ABSI) in predicting chronic diseases and mortality: a systematic review and meta-analysis. Obes Rev. 2018;19(5):737-759.
- Christakoudi S, Tsilidis KK, Muller DC, et al. A Body Shape Index (ABSI) achieves better mortality risk stratification than alternative indices of abdominal obesity: results from a large European cohort. Sci Rep. 2020;10(1):14541.
- Krakauer NY, Krakauer JC. Untangling Waist Circumference and Hip Circumference from Body Mass Index with a Body Shape Index, Hip Index, and Anthropometric Risk Indicator. Metab Syndr Relat Disord. 2018;16(4):160-165.