Why do I over-eat?

Ok so I’m a young, pretty decent looking and slim, educated, in a secure job, amazing mates, travelling the world… really everything is peachy.

So why do i over indulge in food? and when i do it its not just something dumb like a slice of pizza, its a whole pizza. followed by a block of chocolate.

i normally eat extremely healthily, but about once a week i get this massive urge to eat a crapload of food and feel as if i have no self control.

can anyone relate, theorise about why i do it, or make suggestions of how to calm my mind and stop this self-destructive behaviour?