If they're adults, There really is no reason to worry. My first snake ever, a female BP who is my baby, stops eating EVERY year from September to April. As long as the weight loss is minimal, really, there is nothing to worry about.

If you're dealing with ball pythons, they are going to stop eating for you at some point. The only thing you can really do is make sure your husbandry is spot on and offer food. I don't even bother offering food to her from October onwards until she tells me she wants to eat again, and its like that for any adults. They will tell you when they want to eat.