Understanding ABSI: Beyond BMI for Health Risk Assessment

What is ABSI?

A Body Shape Index (ABSI) is a relatively new metric developed in 2012 by researchers Nir Y. Krakauer and Jesse C. Krakauer. It was designed to address some of the limitations of Body Mass Index (BMI) by incorporating waist circumference as a measure of central obesity.

The formula for ABSI is:

While this formula might look complex, it essentially measures how much your waist circumference deviates from what would be expected based on your height and weight. A higher ABSI indicates that you carry more weight around your waist than would be expected for someone with your BMI.

Why ABSI Matters: The Limitations of BMI

BMI has been the standard metric for assessing weight-related health risks for decades, but it has several well-known limitations:

• 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 is particularly important. Research has consistently shown that where you carry your fat matters as much as, if not more than, how much fat you have. Specifically, abdominal fat (especially visceral fat that surrounds your organs) is more strongly linked to health risks than fat in other areas of the body.

This is where ABSI comes in. By incorporating waist circumference relative to BMI and height, ABSI specifically targets the health risks associated with central obesity.

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

Subsequent studies have confirmed these findings and shown that ABSI is particularly useful for identifying health risks in people with normal or overweight BMI.

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.

Improving Your ABSI

If your ABSI is high, you may want to focus on reducing your waist circumference. Here are some strategies that can help:

• Target abdominal fat: While spot reduction isn't possible, exercises that engage your core, like planks and Russian twists, can help strengthen abdominal muscles.
• Cardiovascular exercise: Activities like walking, running, swimming, or cycling can help reduce overall body fat, including abdominal fat.
• Strength training: Building muscle mass can improve your 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 can contribute to abdominal fat accumulation, so practices like meditation, yoga, or deep breathing may help.
• Adequate sleep: Poor sleep is associated with increased abdominal fat, so aim for 7-9 hours of quality sleep per night.

ABSI vs. Other Body Composition Metrics

ABSI is one of several metrics used to assess body composition and health risks:

• 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.

Each metric has strengths and limitations. For the most comprehensive assessment, consider using multiple metrics. For example, check your BMI, ABSI, and body fat percentage to get a more complete picture of your body composition and health risks.

Conclusion

ABSI represents an important advancement in our understanding of how body shape affects health. By accounting for waist circumference relative to BMI and height, it provides valuable information about health risks that BMI alone misses.

While ABSI is a useful tool, it's important to remember that no single metric can capture all aspects of health. ABSI should be used alongside other metrics like BMI and body fat percentage, and in consultation with healthcare professionals, to get a comprehensive picture of your health status.

Use our ABSI Calculator to determine your ABSI and z-score, and check out our other calculators for a more comprehensive health assessment.