I used to think that if you had a bad day during a diet, the several pounds you could put on in one day was just fluid, and if you get straight back to it again, you will lose than fluid pretty quickly.
You will lose it pretty quick of course, but im sure its far more complex than just fluid, there are so many different things going on in the body, it isnt just a simple sum of calories. Insulin plays a big part, as it is responsible for fat storage. Binge on high carb foods, and you produce a lot of insulin to bring the subsequent high glucose levels down, forcing the fat back into the fat cells. When you on a diet you naturally reduce your bodies requirement for high levels of insulin, therefore you will then lose the weight.
This is why low carb diets work, it keeps the requirement for insulin down, your blood sugars are more stable, and you dont get the highs and lows that trigger yet more hunger pangs.
People with uncontrolled diabetes will lose weight even if they eat too much food, blood sugars rise, there isnt enough insulin to deal with it so the excess glucose is lost through urine instead of being stored in the fat cells. This happened to me about a year ago when i lost a stone in weight very quickly without even trying. I was delighted, however my doctor was not delighted even though i really did need to lose weight.
If you are gonna binge, the answer is to go on a low carb binge, this might sound like weird advice, but it will limit the damage and may even have no effect on your weight at all (im talking about a one day binge here, not a 3 month all out whoopee)