To lose weight successfully, you either have to decrease your caloric intake or increase the number of calories expended through exercise; preferably both. To lose weight successfully and keep it off, you have to accomplish calorie reduction without feeling deprived. This is a key concept. Feeling deprived comes around and kicks you in the rear end right in the direction of the nearest hot-fudge sundae or the local bakery.
Individuals trying to lose weight ordinarily don't have feelings of deprivation; they bury them instead --- paraphrased from Dr. Howard M Shapiro in Picture Perfect Weight Loss. They say that they had a bad week or that they ate because they weren't focused. They will say things like, "I had plenty. I didn't need to eat the brownie"; "I wasn't hungry"; or "I don't know why I did it." If those phrases sound familiar, I can assure you that people who are deprived of food do need to eat. If you eat, it's because you're hungry.