As people get older, their belly fat tends to increase — and this increase is a bit more clearly linked to age when measured with ultrasound than when just measuring the waist.

Measuring belly fat with an ultrasound shows a stronger link to bad blood sugar, cholesterol, and fat levels than just measuring waist size, even when you account for a person’s age, sex, and overall weight.

As people get older, they tend to have more fat around their organs and less under the skin, making weight and waist measurements less reliable for detecting health risks in seniors.

Just measuring your waist size doesn’t tell you as much about your blood sugar and cholesterol levels as an ultrasound scan of your belly fat does — even when you already know someone’s weight and age.

In middle-aged adults, having more fat around the internal organs is linked to a faster rate of cardiovascular aging, with each additional liter of this fat corresponding to an extra 0.656 years of biological aging in the heart and blood vessels, even after accounting for overall body weight and chronological age.