There was an article in maxim this month about losing weight.
Cut your daily calorie intake by 250 calories. That's about one 20oz bottle of coke. Get some exercise each day, jog for 15 minutes or walk for 30. That should cut your caloric intake by 500 calories a day total (skipping 250 of them and burning 250 with exercise.) According to the article, a person can lose about one pound a week this way.
It's not the fastest, but its the easiest (come on, how hard is it to find 1/2 an hour to walk around the neighborhood and forgo the bottle of coke on the morning commute) and probably the healthiest.