I agree that many boxers can lose a pound in a couple of hours, but I'm not sure how beneficial that really is. In my mind, having to lose weight at the last minute usually has negative consequences. As for over-training, who knows? It's all kind of a gray area. I think it's different for each fighter, how they approach the weight loss. For some, being a pound over a week from the fight might be good, whereas for others, they may prefer being 2 or 3 pounds over a week before.