An Alternative to BMI

Body Mass Index (BMI) is a well-recognized part of everyone’s vocabulary when we talk about weight. It is the most commonly used measurement of body size, yet it is not a perfect indicator of obesity or risk. BMI is a measurement based solely on weight and height, and doesn’t take into account other factors such as body composition — for example, how much muscle versus fat a person has.

BMI also doesn’t account for body shape. Research has shown that people who have abdominal obesity, often referred to as being “apple-shaped” are at higher risk for many health conditions, compared to those who carry their weight in their hips and thighs (or ‘pear-shaped’).

There is an alternative measure of body size, called Body Shape Index (ABSI), which takes into account the risks of abdominal obesity. New evidence highlights the importance of ABSI as a predictor of mortality. A study of more than 7000 adults found that death rates increased by a factor of 1.13 for each standard deviation increase in ABSI. Those with ABSI in the top 20 percent were found to have death rates 61 percent higher than those with ABSI in the bottom 20 percent.

The study found that ABSI outperformed BMI as an indicator of risk of premature death, and outperformed commonly used measures of abdominal obesity: waist circumference, waist – hip ratio and waist – height ratio.  ABSI can be used in practice to calculate a person’s risk from abdominal obesity in a convenient form that is complementary to BMI and to other known risk factors. Finding ways to best quantify obesity and related health risk is a work in progress, and important in terms of more clearly identifying patients who could most benefit from treatment.

“It is refreshing to see an attempt to better identify patients at risk for medical problems related to obesity, said Dr. Kim Marley, weight loss surgeon at Alleghenies Surgical.  “The BMI has always been a relatively crude approximation of obesity. Using a standard BMI calculation, both an athlete that is 5′ 11” and 220 pounds with 2 percent body fat and a “couch potato” with the same height and weight but 25 percent body fat are considered obese (BMI 30.7).”

“Using waist circumference is an excellent step forward in determining those patients at risk for obesity related comorbidities. Abdominal fat content is closely associated with the metabolic syndrome and, if measurable, would be a better predictor of risk. The strong correlation between ABSI and mortality shows we may be on the right track in predicting risk, as well as identifying patients who may most likely benefit from weight loss surgery,” Dr. Marley concluded.

You can calculate your ABSI here.

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