I don't really remember where i heard of this, but if you behave five days out of the week and indulge more on the weekends, it reduces cravings and spikes metabolism. Also, it's a nifty reward for behaving five days out of the week!!
KEEP IN MIND: Indulge more does not mean a free for all. It just means you're a little bit more free to eat the food that isn't great for you, such as chocolate, snack foods like funny bones, caffine, etc. But you have to keep on track the other five days. By the way, I'm living proof this works!