A Body Shape Index (ABSI) Calculator

Use this calculator to assess your risk factors related to obesity. It employs the scientifically validated "A Body Shape Index" (ABSI) formula that offers a more accurate evaluation of health risks compared to the traditional body mass index (BMI).

To begin, enter your sex, age, height, weight, and waist circumference into the calculator. It is very important to measure your waist circumference accurately to ensure accurate and reliable results. Follow the instructions below on how to measure your waist. Once you have entered all the information, click the "Calculate" button to generate your results.

Measuring Waist Circumference: Use a flexible measuring tape made of non-stretchable material. Remove clothing or measure over thin, form-fitting clothing to avoid adding extra bulk. Locate the midpoint between the lower edge of your last rib (bottom of the rib cage) and the top of your iliac crest (the top of your hip bone). This is typically near the navel but may vary slightly depending on your body shape. The tape should be wrapped snugly, parallel to the floor, without compressing the skin. Stand straight with feet shoulder-width apart, relax, and breathe normally. Avoid sucking in your stomach or flexing your muscles, as this can skew results. Measure at the end of a normal exhalation.

A Body Shape Index (ABSI)

The Body Mass Index (BMI) is a commonly used measure for assessing obesity, but it has well-known limitations that can impact its applicability.

To address these limitations, researchers developed a new formula known as the "A Body Shape Index" (ABSI). It was introduced in 2012 by Nir Y. Krakauer and Jesse C. Krakauer in a study published in PLoS ONE. It was developed as a way to quantify the risk associated with abdominal obesity, where obesity is indicated by a wide waist circumference (WC) relative to a person's height and body mass index (BMI).

Medical exam and mortality data were analyzed on a sample of more than 14,000 adults participating in the United States (USA) National Health and Nutrition Examination Survey (NHANES) 1999–2004. They found that an above-average ABSI was associated with a substantially higher risk of death. Additionally, the excess mortality hazard associated with high ABSI was greater than that associated with above-average BMI or waist circumference.

The study concludes that even though you may have a normal BMI, you may be at a greater risk of dying sooner if you carry excessive weight in your midsection relative to your height and weight.

Why is waist circumference more important than weight?

Waist circumference is more important than weight alone when assessing health risks, as it directly measures abdominal fat, particularly visceral fat surrounding internal organs. This type of fat is strongly associated with an increased risk of cardiovascular disease, type 2 diabetes, and premature death. While weight and BMI provide an overall assessment of body mass, they do not differentiate between muscle, bone, and fat, nor do they indicate where fat is stored in the body.

When waist circumference is combined with BMI, the ability to identify individuals at high risk for serious health problems improves significantly. Studies show that after adjusting for BMI, higher waist circumference is consistently associated with a greater risk of morbidity and mortality, even among people with normal BMI. This is because waist circumference better reflects the accumulation of harmful visceral fat, which is metabolically active and contributes to insulin resistance and inflammation.

How does ABSI improve understanding of abdominal obesity risks?

ABSI enhances understanding of abdominal obesity risks by focusing specifically on waist circumference in relation to body size and mass rather than relying solely on overall weight or BMI.

ABSI is more independent of height and weight than other indices because its formula is specifically constructed to minimize the influence of these factors. Unlike BMI, which is simply weight divided by height squared, ABSI normalizes waist circumference (WC) by a value predicted from the allometric relationship between weight and height. This means that ABSI adjusts WC for what would be expected based on a person's height and weight rather than just using raw measurements.

By doing this, ABSI provides a measure of abdominal obesity that is mainly independent of overall body size. A high ABSI indicates that a person's waist circumference is larger than expected for their height and weight, suggesting a more central concentration of body mass, potentially reflecting higher visceral fat. This independence enables ABSI to identify individuals at increased risk for health problems associated with abdominal obesity, even if their overall weight or BMI falls within normal ranges.

Other indices, such as BMI or simple waist circumference, are more directly influenced by height and/or weight, making it harder to distinguish between individuals with high muscle mass or generalized fat accumulation and those with dangerous abdominal fat accumulation. ABSI provides a more precise assessment of abdominal obesity risk that's independent of height and weight.

This ABSI calculator also provides a risk score, known as an ABSI z-score, which compares a person's score to the average scores for their age and gender. This process helps users and healthcare providers identify individuals at high risk for complications from abdominal fat, regardless of their overall body size.

Comparisons of Anthropometric Indices

A 2020 study [3] was conducted on a large group of people in Europe to determine the usefulness of various body shape indices and ratios in assessing the risk of mortality related to obesity. The study examined various waist circumference-based anthropometric indices for comparison, including the A Body Shape Index (ABSI), Body Roundness Index (BRI), Waist-to-Hip Ratio (WHR), Waist-to-Height Ratio (WHtR), Weight-adjusted Waist Index (WWI), and many others.

The study found that ABSI provides a more accurate assessment of mortality risk than other measures. ABSI, which is designed to be independent of BMI, works well in conjunction with BMI and helps to effectively categorize the risk for underweight, obese, and overweight individuals, as well as those with average weight.

Frequently Asked Questions about ABSI

Caution! This calculator is intended for illustrative and educational purposes only, and it is not for medical use. The body shape index and ratio formulas should be used in conjunction with BMI.