Subcutaneous fat

Subcutaneous fat is the adipose layer between skin and muscle. It makes up the large majority of body fat in most people, and its distribution — hips and thighs, or abdomen and trunk — varies with sex, genetics and hormones.

It matters because it is metabolically much less troublesome than visceral fat, the deeper fat surrounding the organs. Subcutaneous fat on the hips and thighs in particular carries little metabolic risk and may even be mildly protective; it is chiefly a matter of appearance rather than health.

In practice you cannot choose where fat comes off. Spot reduction does not work: a deficit mobilises fat systemically, and the order in which regions respond is largely genetic. Calliper measurements estimate this layer specifically, which is why they miss visceral fat entirely.