Do a pinch test
Fat and skin are easy to tell apart.
The skin is not thick, measuring approximately 1 centimeter.( 1/5 of an inch) fat varies in thickness. The best way to figure out how much fat is located in a certain area, is to do a pinch test. Simply take your thumb and index finger, and pinch your abdomen. If you find a thickness of 1 to 5 inches, this is mostly fat since skin thickness is quite small.