A simple ratio that may predict risk better than BMI
Waist-to-height ratio (WHtR) divides waist circumference by height, producing a single number that's increasingly cited in research as a stronger predictor of cardiovascular and metabolic risk than BMI alone — particularly because it directly captures central (abdominal) fat, the type most strongly linked to heart disease and type 2 diabetes risk.
WHtR = waist circumference ÷ height
The appeal is its simplicity: unlike BMI, which needs separate reference charts for children, adults, and different ethnicities, a single threshold — roughly 0.5 — works reasonably well across a broad range of ages, heights, and both sexes, which has made "keep your waist circumference under half your height" a popular, easy-to-remember public health message.
How to measure correctly
Measure waist circumference standing upright, at the end of a normal exhale, at the narrowest point of your torso — usually just above the belly button for most people. Avoid pulling the tape tight enough to compress the skin, and try to measure at a consistent time of day for comparable readings over time.
What the categories mean
A ratio below 0.5 is generally considered healthy. Between 0.5 and 0.6 suggests increased risk and is often a useful prompt to look more closely at lifestyle factors — diet, activity, sleep. Above 0.6 is associated with meaningfully higher risk and is worth discussing with a healthcare provider, particularly alongside other risk factors like family history or blood pressure.