Body fat isn’t a single, uniform tissue. Two types sit at opposite ends in terms of health impact: subcutaneous fat, which sits just under the skin, and visceral fat, which wraps around internal organs deep in the abdomen.
Subcutaneous fat is the pinchable layer most people associate with body fat. While excess amounts aren’t ideal, it’s metabolically far less active and less strongly linked to disease risk.
Visceral fat is different. It releases inflammatory compounds directly into the bloodstream and is closely tied to insulin resistance, type 2 diabetes, and cardiovascular disease — even in people who aren’t overweight by BMI standards.
Waist circumference is a simple, practical proxy for visceral fat, since it doesn’t show up as clearly on a scale. A waist above roughly 35 inches for women or 40 inches for men is generally considered a signal worth discussing with a doctor.
The encouraging part: visceral fat responds well to lifestyle changes. Regular aerobic activity, reduced added sugar, and adequate sleep all specifically target visceral fat, often before major changes show up on the scale.