It is a myth - in fact, it is good to have a non-caffeinated drink (water or sports drink) before you go to bed, it keeps you hydrated.Understand that weight = input (calories) - output (exercise) - and that doesn t depend on the time of the day.
not anything that is loaded with calories tho.....if you do try water.....its easy to lose although sometimes we can retain it if you drink too much and not work out but you can sweat it out or urination