The study, published in JAMA Network Open, found that measuring waist circumference, either by itself or together with body mass index (BMI), was about as effective as a more complicated new approach that relies on several different body measurements.

The results suggest that something as basic as checking waist size could give doctors and patients a practical way to identify potentially unhealthy levels of body fat and recognize related health concerns earlier.

Waist Size Could Offer an Early Warning

“Pay attention to the need to loosen your belt or get bigger pants,” said Aayush Visaria, a faculty member of the Rutgers Health-RWJBarnabas Health Center for Climate, Health, and Healthcare and lead author of the study. “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. Measuring your waist, along with your weight, can help identify health risks earlier and provide an opportunity to reduce your risk of diabetes, heart disease, stroke and some cancers.”

To investigate how well different obesity screening methods work, Rutgers Health researchers analyzed information from 1,900 U.S. adults between the ages of 20 and 59 who took part in the National Health and Nutrition Examination Survey.

The researchers compared several ways of identifying obesity with a highly accurate method for determining body fat.

Testing Simpler Ways To Detect Obesity

One of the methods evaluated was a recently proposed obesity framework developed by a multidisciplinary group of independent experts. That approach combines BMI, waist circumference, waist-to-height ratio and waist-to-hip ratio.

Although the newer framework identified a larger number of people with excess body fat, the Rutgers team found that much simpler methods produced similar levels of accuracy.

Using either BMI or waist circumference provided a better balance between correctly identifying people with obesity and avoiding false-positive diagnoses. Even when used on its own, waist circumference performed nearly as well.

That simplicity could matter in everyday medicine. Hip circumference, which is needed for one of the measurements in the proposed framework, is rarely recorded during routine clinical visits. Waist circumference is much easier to measure and is increasingly included in clinical guidelines, according to the researchers.

A Tape Measure May Provide Much of the Answer

“Our findings show that you don’t necessarily need multiple complex measurements to identify obesity-related health risks,” said Visaria, who also is an instructor in the Department of Medicine at Rutgers Robert Wood Johnson Medical School. “A waist measurement provides much of the information needed and is feasible for clinicians and patients alike.”

The results also highlighted an important limitation of BMI. When BMI was used by itself, it failed to identify a substantial number of people who met body-fat criteria for obesity.

That finding adds to longstanding concerns about relying only on BMI, which does not fully reflect differences in body composition or show where fat is stored in the body.

Why Waist Measurement Could Matter

Where body fat accumulates can be important for health, which is one reason waist circumference can provide information that BMI alone does not capture. The researchers say wider use of waist measurements could make obesity screening more practical while still identifying many people who may face elevated health risks.

The findings could ultimately help shape future recommendations for obesity screening and encourage routine waist measurements to become more common in health care.

The study is coauthored by Soko Setoguchi of the Rutgers Center for Climate, Health, and Healthcare; Ethan Halm of Rutgers Health; and Douglas Corsi, Dylon Patel, Keerthana Kesavarapu, and Jeffrey Carson of Rutgers Robert Wood Johnson Medical School.