If you want a safe weight loss then you should include water in your weight loss plan along with exercise. Drink a glass of water every time you want to eat snack or anything unhealthy. It help in controlling your eating habits.
If you've never exercised and you start, you don't need any change in diet to lose some weight because you will have added burning of food and speeding of metabolism to your life. But if you've never exercised be careful you don't overdo it. But for lasting weight loss, and this depends on how much you want to lose, it would help to add dietary changes if your current diet has too many foods in it that don't metabolize well.