From my experience, I would say losing weight and keeping it off is like quitting smoking. It takes 7 years of complete abstinence and not relapsing to get it out of your system.
After that, you will have won the battle, but not the war. Unlike quitting smoking, drinking and drugs, which you quit completely, you are still going to continue to eat, but smaller portions. It's like telling a recovering alcoholic, "Now you can go back to drinking, but watch the quantities."
Further, it's much easier to count cigarettes or drinks than calories. Counting calories is more complex, because there are different kinds of calories (fats, protein, simple sugars, complex carbohydrates, fiber, etc.) and you have to look through charts to find out how many calories are in every kind of food. The charts, and even the calories on food labels, are not always accurate. Exercise habits should also be considered when assessing your daily calorie requirement.
This is why I believe overcoming overeating is more difficult than overcoming any other kind of addiction. For addicts, abstinence is easier than moderation, but in the case of food, it is not an option.