I have heard that a lot of ball pythons will fast this time of year, something about the temps and mating season so some of them don't eat. I have a young ball that I just got a little less than three weeks ago, and she hasn't eaten since she's been here, but her eyes are just starting to cloud so maybe she is going into shed and thats why. But if you see really dramatic weight loss, and her body starts to take on an upside down 'V' shape, then you may want to take it to a vet and see if maybe it has internal parasites?