Waist size flags CV risk that BMI finds normal

Clinical takeaway: Consider central adiposity across the full BMI range when estimating cardiovascular risk. A patient in the normal or overweight range with an elevated waist size may warrant closer prevention attention.

Central adiposity has been tied to cardiovascular outcomes for years, but the metric on the vitals screen still reduces body composition to a single ratio of weight and height. The patient with a normal BMI but a thick waist passes through prevention visits without a flag.

Weight is measured at nearly every visit, and BMI is calculated automatically. Waist and hip circumference are not, which means the measurement most likely to separate out cardiovascular risk is the one most likely to be skipped. Whether that omission changes a patient's risk category, and for how many patients, is answerable only at scale: a pooled analysis of 259,388 adults across 15 cohorts, followed a median of 20 years, examined both measures against nine cardiovascular outcomes.

Among adults in the normal weight or overweight range, clinically elevated central adiposity was associated with 15% to 50% higher risk across most of the nine outcomes. And the disagreement was common: 18% of adults with a normal BMI had a high waist-to-hip ratio, 5% had a high waist circumference, and in the overweight range roughly four in 10 had one or the other.

It cut the other way too. Among adults with obesity, 45% had a low waist-to-hip ratio and 9% a low waist. Those with obesity and a low waist size showed no significantly different risk than adults with normal weight and a low waist, and their all-cause mortality risk was lower. That reassurance was sex-specific: women with obesity and a low waist-to-hip ratio still carried significantly higher risk across all nine outcomes than women at normal weight, though below women with obesity and a high ratio. Central adiposity accounted for a large share of the risk that obesity carries: among adults with obesity 13% to 49% of the nine outcomes traced to an elevated waist size or ratio, with the largest shares for heart failure and atrial fibrillation.

Investigators pooled 15 cohort studies with harmonized central adiposity data and at least one of nine endpoints: first myocardial infarction, stroke, heart failure, atrial fibrillation, total coronary heart disease, total cardiovascular disease, and coronary, cardiovascular, and all-cause mortality. Waist circumference was available for 259,351 adults, waist-to-hip ratio for 218,984, and risk was estimated within BMI strata. Body measurements were taken once at baseline, and the cohorts lacked data on physical activity, diet, and genetic obesity risk, all of which shape cardiovascular risk independently.

A waist measurement takes seconds but sits outside the automated vitals flow, so it happens only if someone asks for it. The patients it would catch are the ones least likely to trigger a second look: normal BMI, no obesity diagnosis, a prevention visit that ends in reassurance. Measuring changes what that visit concludes for a meaningful minority of them.

"Our findings emphasize the critical role of identifying elevated central adiposity, even in individuals with a normal BMI or with a BMI in the overweight range. Relying solely on BMI may result in misclassification of cardiovascular risk across a wide range of cardiovascular outcomes," said Zeina Dardari, PhD, MS, lead author and a researcher with the Johns Hopkins Ciccarone Center for Prevention of Cardiovascular Disease.

Source: Dardari Z, et al. (2026 Aug 11) J Am Coll Cardiol. Risk Reclassification Beyond BMI by Waist Circumference and Waist-to-Hip Ratio Across 9 Cardiovascular Outcomes: Results From the Cross-Cohort Collaboration