Skinny fat describes a body that looks slim in clothes but has little muscle and relatively high body fat, often with a soft midsection. Body weight is usually unremarkable, so the scale alone says little about the issue.
The term is not medical but comes from fitness culture. It describes a body composition, not a disease.
Why a hard cut rarely helps
The first instinct is often to diet until the belly is gone. With little muscle, though, a hard cut mainly makes you thinner, not more defined. What is missing is primarily muscle, not a lower weight.
A bulk with a large surplus is not a great idea either. According to an analysis by Forbes 2000, people who already carry relatively more fat turn a smaller share of a surplus into fat-free mass.
What usually works better
Skinny fat is the classic case for the middle ground between bulking and cutting. If you are a beginner, progressive strength training at maintenance or with a very small surplus gets you the most, together with plenty of protein. You often build muscle and lose some fat at the same time. That is called body recomposition, and it works best for beginners and people with a bit more body fat.
Tracking progress
Because the scale stays nearly flat, you need other measurements: waist size, photos under the same conditions and your strength numbers in the gym. A body fat estimate, for example with the Navy method, and your FFMI help you place yourself, but they are often too imprecise for small changes. Give it at least eight to twelve weeks.