Can you tell me how much weight can you lose from purging?

Brief, Non Sustained: Purging by throwing up after meals or by using laxatives or diuretic is a poor method of weight loss. It is also incredibly dangerous. Athletes that have to drop weight for a weigh in for a fight frequently learn the hard way that the trauma of losing 5-7% of your body weight in a day or two causes them to be drained (or worse, electrolyte derangements.) you will regain all the weight in days.