Subcutaneous fat

Subcutaneous fat is the fat stored directly under the skin, as opposed to visceral fat packed around the organs inside the abdomen. It is the fat you can pinch, and it accounts for the large majority of body fat in most people.

It is not merely padding. It insulates, cushions, stores energy efficiently, and acts as an endocrine organ, releasing leptin and adiponectin among other signals. A body with too little of it, as in lipodystrophy, develops severe metabolic problems, which is a useful corrective to the idea that fat is simply surplus.

Where it sits varies, and the pattern is partly hormonal and partly genetic. Fat carried on hips and thighs is associated with lower metabolic risk than fat carried around the middle, and gluteofemoral fat in particular appears mildly protective.

Compared with visceral fat, it is metabolically quieter. Visceral fat drains directly to the liver and produces more inflammatory signalling, which is why waist measurement predicts risk better than total body fat does and why two people at the same weight can have quite different risk profiles.

It is also the more stubborn deposit subjectively, since visceral fat tends to mobilise earlier in a deficit. That is why metabolic markers often improve before the mirror does, which is worth knowing before you conclude a diet is not working.

Spot reduction does not work. Training a muscle harder does not preferentially remove the fat above it, and the devices and creams sold on that promise have no meaningful evidence.

In practice, judge progress with a tape measure at the waist alongside the scale, and use our body fat and waist to height calculators rather than a single number.