Diet & Fitness: What is the cause of this? Can it be explained?

I'll make it short. I am normally about 10lbs overweight. I often try to lose and keep that weight off. When I do this I work out often and try to eat right. I eat enough calories and DONT starve myself. I usually keep this up for weeks. Then, out of nowhere, I start eating too much and it doesnt stop. I literally go on a binge and gain most of the weight back. Then the cycle goes around again.