What it means
Most body fat is subcutaneous, the kind you can pinch. Visceral fat sits inside the abdominal cavity. It is more metabolically active and is closely linked with insulin resistance, type 2 diabetes, high blood pressure, fatty liver disease and heart disease.
People with a normal BMI can still carry excess visceral fat, which is one reason BMI alone can miss risk. CT and MRI scans measure visceral fat most accurately, and some DEXA machines estimate it, but these are rarely used for routine care.
In practice, waist circumference and waist-to-height ratio serve as simple stand-ins. Large studies link a bigger waist with higher risk even after accounting for BMI.
Visceral fat often responds well to overall weight loss and regular physical activity. Spot exercises like sit-ups do not specifically target it.
Why it matters
Losing visceral fat is linked to many of the metabolic gains people hope for from GLP-1 treatment.