Body Mass Index (BMI) has been long believed by health experts to be the best way to measure the amount of fat in the body, and widely accepted by the public to be so. However, a new study has shown that BMI might not be the best tool to measure body fat, after all.
BMI takes into account only the person's height and weight in calculating the fat content in his body. The study says that a new way of measuring body fat, called the A Body Shape Index (ABSI) is a more reliable way of measuring body fat because takes into account where the weight is concentrated. Because of this, ABSI is therefore a more reliable too in predicting mortality, as proven in an earlier study conducted in 2012 and published in PLOS ONE.
Professor Nir Krakauer, an assistant professor of civil engineering in City College of New York's Grove School of Engineering and his father, Jesse Krakauer, MD, led the two studies. Together they developed the ABSI.
The 2012 study stated that since obesity that exceeds threshold values is a leading cause of death all over the world, abdominal fat deposits do need to be measured, and BMI does not have the capacity to do this. It concluded by saying that, "Body shape, as measured by ABSI, appears to be a substantial risk factor for premature mortality in the general population derivable from basic clinical measurements. ABSI expresses the excess risk from high WC in a convenient form that is complementary to BMI and to other known risk factors."
This new study, also published in PLOS ONE, is a follow up to the one done in 2012. The new study analyzed data collected from the 7,011 adults aged 18 years old who participated in Great Britain's first Health and Lifestyle Survey (HALS1) during the 1980s. The study also took into account the results from the follow-up survey, HALS2, carried out between 1992 and 1992. The participants broadly represented British demographics as to region, employment status, national origin, and age.
The researchers then looked for death and cancer rates from data that was gathered through the National Health Service in 2009, in which they found that 2,203 people from the sample population had died. Then they did a comparison between the deaths and the BMI and ABSI data taken from the surveys, which included waist circumference, waist-to-hip ratio, and waist-to-height ratio.
The analysis has revealed that the risk factors for death increase by 1.13 for each standard deviation increase in ABSI. The researchers have also found that persons with ABSI in the top 20 percent of the group studied had death rates that are 61 percent higher than those with ABSI in the bottom 20 percent of the group studied. These findings further supported the results from and conclusions made in the 2012 study.
"Since determining ABSI only requires a waist circumference measurement in addition to the standard height and weight measurements used to determine BMI while WHR additionally requires a hip circumference measurement, ABSI may also be the more clinically convenient of the two metrics," the researchers said.
The ABSI is calculated by factoring in an individual's gender, age, height, weight, and waist circumference. An online ABSI calculator, made available by Professor Nir Krakauer, can yield results in mere seconds, which shows, among others, the person's BMI, ABSI, relative risk from BMI, relative risk from ABSI, and relative risk from BMI and ABSI combined.
ABSI's significance lies in its ability to provide a more accurate and reliable base data on body fat that can help individuals and their doctors decide what lifestyle changes are required to be implemented to control body fat.
"Mortality risk appears to track changes in ABSI over time, motivating further research into whether lifestyle or other interventions could trigger reduction in ABSI and incur the longevity benefits seen in this study for those with lower ABSI," the latest research concluded.
