I've been running for almost two months, and my weight is also dropping. The belly looks obviously smaller, but the legs and arms don't seem to be big either.
Running is not like fitness. Running is a continuous whole-body exercise. After you insist on running for a period of time, you will gradually consume whole body fat to lose weight. However, it seems that the fat content in these parts of legs and arms is generally low, so it is difficult for running to make these parts achieve obvious weight loss effect at once, which can only make these parts look more linear.