diet is definately a huge factor, try eating less during a meal but more times a day.
By cutting back on food and starving yourself, your body will tend to hold on to the fat rather than drop it because your sending your body messages that your not receiving enough nutrition and energy so your body is gonna hold on to the fat as a back up energy source. Instead what you should do is just eat less during dinner or before you go to sleep (cuz that shit builds fat like no other) and cut back on your lunch portions and eat 2-3 snacks a day. Preferably fruits or something of the sort.
Running will burn fat too, but its gotta be an everyday thing
hope this helps