If you are trying to shed few pounds, kilos, stones or whatever other unit you measure the weight in, exercising and running is a great way to achieve your goal. However if your goal is to run a marathon, don’t cut down on your food intake too drastically. You need food to fuel you. This is of course not a free out of the jail card for overeating.
The important thing is what food to eat and what food to avoid. Healthy and fresh will always beat sugary and fried whether you are aiming for one or the other.