Let me say straight up that I do not condone purging as a way of managing weight. Purging does a great deal of damage due to stomach acid. It severely burns the esophagus and dissolves the teeth (I have severe gastric reflux so I have tooth damage similar to that found with bulimia, and it's unpleasant: the enamel is so thin as to be transparent and I have extreme sensitivity as a result). I know of no way to help people not purge, I'll leave that to others with more experience. Everybody lapses, so I expect many could find this advice useful. Also, you should brush your teeth afterwards with a lot of toothpaste, focusing on the inside of the teeth. I'm not sure if everyone knows that or not. It is very helpful in preventing acid damage to teeth, as well.