Takes weeks to develop even 1lb of muscle and exercise to reduce body fat is a really slow burner too. Muscle sits below any body fat you have. Reduce this and you will see your muscles, but its very very hard to develop muscle in a short space of time, and takes resistance work (weights etc) rather then running which is a cardio form of exercise. Maybe try running up hills, lunges, squats and heel kicks/knee kicks as you run.
To lose body fat (if you need to) its all about what you eat rather then how much exercise you do. Body fat can also be very hard to reduce even when your eating properly and reducing calories. To lose weight, you need to eat less then your body requires to maintain your weight. As you do this, your body needs then to tap into other forms of energy and it does this by breaking down both fat and muscle. The exact ratio of each varies depending on genetics, depending on what form of exercise you do, depending oh cortisol levels and if you allow yourself to become starving hungry...depends on lots of things so if your going to cut down, do so sensibly!
But if you do not need to lose any weight, don't do any cutting back with your food. If your looking for a physical change in your body, try adding in resistance training to your running. Running is a very poor form of exercise to build and create muscle alone. And you also would benefit from additional forms of exercise to train muscles that running cannot.