Bulemia can be about control. You cant control your surroundings so you control what you take in, or keep in your body (its subconscious though)
Also, when stressed when life is full of chaos your way of dealing is perging. When you perge your body sets off endorphins and for a few minutes you feel better.
I was anorexic for years but didnt know it, it was the same idea. Your body goes into emergency mode and you get weird energy spurts and feel better temporarily