A simple waist measurement may identify obesity nearly as well as more complicated methods — and catch cases that body mass index alone can miss, according to a new Rutgers Health study.

The study, published in JAMA Network Open, found that waist circumference alone performed nearly as well as approaches incorporating multiple body measurements when researchers compared them with scans measuring body fat.

Researchers analyzed data from 1,900 U.S. adults ages 20 to 59 who participated in the National Health and Nutrition Examination Survey. The study compared several ways of identifying obesity against body-fat measurements obtained using dual-energy X-ray absorptiometry, or DEXA.

Among the methods was a recently proposed obesity definition incorporating BMI, waist circumference, waist-to-height ratio and waist-to-hip ratio.

Researchers found that a simpler approach using either BMI or waist circumference provided a better balance between identifying people with obesity and avoiding false-positive diagnoses. Waist circumference alone performed nearly as well.

BMI alone, meanwhile, had the lowest overall diagnostic accuracy of the methods studied and identified only about half of adults who met the study's body-fat criteria for obesity.

“Pay attention to the need to loosen your belt or get bigger pants,” lead author Aayush Visaria of Rutgers Health said in a statement. “Although clothing size isn’t the same as a proper waist circumference measurement, it can be an early sign of unhealthy amounts of body fat.”

Researchers said waist circumference has a practical advantage because it is relatively easy to measure.

The researchers said the findings support using BMI or waist circumference, or waist circumference alone, when identifying obesity in clinical practice.

The study was limited to adults aged 20 to 59, meaning its findings may not apply to children or older adults.