Study: Waist Circumference More Accurate Than BMI in Detecting Health Risks
A simple waist circumference measurement turns out to be nearly as effective as other, more complicated methods in detecting unhealthy body fat levels. New research from Rutgers Health shows that body mass index (BMI) alone often fails to identify many people with obesity, so waist size could serve as a crucial early warning sign.
The study, published in JAMA Network Open, found that measuring waist circumference—whether done on its own or combined with BMI—has effectiveness equivalent to newer, more complex approaches that rely on various different body measurements.
These results indicate that waist circumference checks provide a practical way for doctors and patients to identify potentially unhealthy body fat levels and recognise related health problems earlier.
“Pay attention to the need to loosen your belt or buy larger trousers,” said Aayush Visaria, a faculty member at Rutgers Health-RWJBarnabas Health Center for Climate, Health, and Healthcare and the study’s lead author.
According to Visaria, although clothing size is not the same as a precise waist circumference measurement, it can be an early sign of an unhealthy amount of body fat. Measuring the waist together with body weight can help identify health risks earlier, providing an opportunity to reduce the risk of diabetes, heart disease, stroke, and even some types of cancer.
To investigate the effectiveness of various obesity screening methods, Rutgers Health researchers analysed information from 1,900 adults in the United States aged between 20 and 59 who participated in the National Health and Nutrition Examination Survey. They compared several ways of identifying obesity with a highly accurate method of determining body fat.
One of the methods evaluated was an obesity framework recently proposed by an independent multidisciplinary expert group. That approach combines BMI, waist circumference, waist-to-height ratio, and waist-to-hip ratio.
Although the new framework identified a greater number of people with excess body fat, the Rutgers team found that a far simpler method produced similar levels of accuracy. Using BMI or waist circumference alone provided a better balance between correctly identifying people with obesity and avoiding false positive diagnoses.
This simplicity is particularly important in everyday medical practice. Hip circumference, which is required for one of the measurements in the proposed framework, is rarely recorded during routine clinical visits. By contrast, waist circumference is far easier to measure and is increasingly being included in clinical guidelines.
“Our findings show that you do not always need multiple complex measurements to identify obesity-related health risks,” said Visaria. “Waist measurement provides much of the information needed and is feasible for both clinicians and patients.”
The study results also highlight the significant limitations of BMI. When BMI is used alone, the method fails to identify a large number of people who actually meet the body fat criteria for obesity. This reinforces long-standing concerns about relying solely on BMI, which does not fully reflect differences in body composition or indicate where fat is stored in the body.
The location of body fat accumulation is very important for health. This is the reason why waist circumference can provide information that BMI alone does not capture. The researchers hope that wider use of waist measurement can make obesity screening more practical while still being able to identify individuals facing high health risks.
The research was also compiled by Soko Setoguchi, Ethan Halm, Douglas Corsi, Dylon Patel, Keerthana Kesavarapu, and Jeffrey Carson from various departments at Rutgers University.