I get intoxicated last week, today i'm recovered but i losed 5kg in 3 days, is that normal?

Mostly Water Loss: You are, no doubt, very dehydrated and need to replenish fluids. This is to a large degree what causes symptoms of hangover. The brain which normally floats starts to sag on its suspensory ligaments which are the only structures inside the skull that contain sensory nerves. You probably didn't eat much over the last few days but water loss probably accounts for at least 2/3 of your weight loss.