what will happen to my legs if i run or jog ?

Running and jogging a lot almost every day will help you burn fat and built muscles too. As your muscles grow you will burn more and more fat. Finally you will become thinner and your body will show much more beautiful. You won't get fatter unless you do weight exercises and eat a lot of food. So if you are careful with your diet, there is no reason to worry about. Just don't push yourself a lot from the beginning because you can suffer from leg pains.

Good luck!

It depends what kind of running you're doing. If you're doing track-type stuff (like fast repeated sprints) you'll likely develop large muscles. If you're doing more of a cross country thing (3 or more miles at a slow pace), you'll just lose fat and your legs will tone a bit. It also depends on your diet.

you'll get slim legs as well as whole body if you do jog or run everyday.. With a proper diet too.. Look at the runners.. The have slimmer legs.. btw, girls naturally have fatter legs than boys.

first it'll have less fat and if you continue, it'll get muscular