Measuring waist size may be one of the simplest and most effective ways to identify obesity-related health risks, according to a study by Rutgers Health researchers. The findings suggest that waist circumference can provide useful information about unhealthy levels of body fat and may help identify people at increased risk of chronic diseases.
The study, published in JAMA Network Open, found that combining body mass index (BMI) with waist circumference—or using waist circumference alone—performed about as well as a newly proposed definition of obesity that relies on several body measurements. This suggests that a relatively simple measurement may offer much of the information needed for obesity screening.
Researchers analysed data from 1,900 U.S. adults aged 20 to 59 who participated in the National Health and Nutrition Examination Survey. They compared several methods of diagnosing obesity against a highly accurate measure of body fat to determine how well each approach identified people with excess body fat.
The researchers also examined a recently proposed obesity framework developed by a multidisciplinary group of independent experts. The framework incorporates BMI, waist circumference, waist-to-height ratio and waist-to-hip ratio. Although this approach identified more people with excess body fat, the researchers found that simpler methods achieved similar accuracy.
In particular, using either BMI or waist circumference provided a good balance between correctly identifying people with obesity and avoiding false-positive diagnoses. Waist circumference alone performed nearly as well. This is important because waist measurement is relatively easy to perform and can be incorporated into routine health assessments without requiring specialised equipment.
“Pay attention to the need to loosen your belt or get bigger pants,” said lead author Aayush Visaria, a Rutgers Health faculty member. Although clothing size is not a substitute for properly measuring waist circumference, Visaria said changes in clothing fit may provide an early indication of unhealthy amounts of body fat. Monitoring both waist size and weight could therefore help identify health risks earlier.
The study also highlighted some limitations of relying on BMI alone. Researchers found that BMI missed a substantial number of people who met body-fat criteria for obesity. BMI is based on weight relative to height and does not fully account for differences in body composition or where fat is distributed. Waist circumference can provide additional information about abdominal fat, which is associated with risks such as diabetes, heart disease and stroke.
The findings could help shape future recommendations for obesity screening and encourage wider use of waist measurements in routine health care. The researchers noted that some measurements included in newer obesity frameworks, such as hip circumference, are rarely collected in everyday clinical practice. Waist circumference, by comparison, is increasingly recognised in clinical guidelines and is practical for both clinicians and patients. As Visaria explained, multiple complex measurements may not always be necessary: a simple waist measurement can provide valuable information for identifying obesity-related health risks.
More information: Aayush Visaria et al, Lancet Definition vs Other Criteria for Obesity Diagnosis in Adults, JAMA Network Open. DOI: 10.1001/jamanetworkopen.2026.27738
Journal information: JAMA Network Open Provided by Rutgers University
