It tends to be the case of thin people who however has a prominent belly. This is due to a chronic contraction of the lumbar muscles causing a curvature exaggerated with consequent antagonists, in this case, the abdominal muscle flaccidity.
Conversely, if you have abdominal fat, the most effective way to eliminate it is diet supplemented with exercise.
The most effective exercises are aerobics that uses large muscle groups such as legs, back, chest and buttocks, which consume large amounts of energy that comes from the body fat reserves.
Force, through the so-called basic exercises also encourages those large muscle groups. But these exercises are effective for weight lose only when you manage to increase enzyme activity and muscle fiber cross-sectional volume.
The abdominal, as you’ve mentioned, do not burn fat or eliminate fat, only tone they harden all the muscular planes, and adipose tissue will still be present, unless through the diet, you produce a caloric deficit that will allow you to lose weight.