A widely used tool for assessing health risk may be missing something important. New research suggests that where fat is carried on the body, not just how much someone weighs, may play a bigger role in predicting high blood pressure.
In a study of more than 19,000 people in the United States, researchers found that a person’s waist-to-height ratio was more strongly linked to both elevated blood pressure and hypertension than body mass index, or BMI. The findings, published in the Journal of Nutrition, point to a growing shift in how experts think about body composition and health risk.
BMI has long been the standard for defining overweight and obesity, but it does not distinguish between fat and muscle. That limitation has raised concerns about how well it reflects actual health risk. The waist-to-height ratio, by contrast, focuses on abdominal fat, which is more closely tied to cardiometabolic conditions.
Using data from the National Health and Nutrition Examination Survey between 2015 and 2023, the researchers compared how well different measures of body fat predicted blood pressure outcomes. They found that people classified as having high fat levels based on their waist-to-height ratio were 50% more likely to have elevated blood pressure and 82% more likely to have hypertension. Those with the highest levels of fat had even greater risk.
The pattern held across age groups, though the relationship was strongest among adults ages 25 to 65. Among younger people, higher waist-to-height ratios were linked to elevated blood pressure, but not to diagnosed hypertension, which was still relatively uncommon in that group.
BMI told a slightly different story. While higher BMI was associated with elevated blood pressure, it was not consistently linked to hypertension once other factors were taken into account. The researchers suggest that BMI may blur the picture by combining fat and muscle into a single measure, potentially overstating risk in some cases and missing it in others.
The idea behind waist-to-height ratio is simple: a person’s waist circumference should generally be less than half their height. While that rule of thumb has been discussed for years, this study adds new evidence that it may better reflect risk tied to excess body fat, particularly fat stored around the abdomen.
Still, the findings come with important caveats. This was an observational study, meaning it cannot prove that body fat distribution causes high blood pressure. It also relies on statistical associations rather than clinical diagnoses based on a single measurement. And while waist-to-height ratio may offer a useful screening tool, it does not replace medical evaluation or other health markers.
For now, the takeaway is less about choosing one number over another and more about understanding what those numbers represent. Weight alone does not tell the full story. Where fat is stored, and how it interacts with overall health, may matter just as much.
The research group was supported by multiple Finnish foundations and research organizations, including the Jenny and Antti Wihuri Foundation, the Finnish Cultural Foundation, the Finnish Foundation for Cardiovascular Research and the Novo Nordisk Foundation, among others.