Fastest way to shed 25-35 pounds? And a helpful diet. Please!?

I'm about 5'5 and 145-150 pounds I need to lose weight now! I'm actually going to start running with my brother whose joining the Marines a mile a day. But the thing is I don't know if I could cut down my eating, what's an alternative that will help me stop eating? Because I want to be at 120lbs again. Please help and only answer if you could give helpful advice! Please and thanks!