There at a good size that if they lose 50 or so grams they will be fine. I wouldn't worry till 100+ grams. I have a girl at 240 grams and hope she eats soon to but if she loses 70 grams I will worry because she's young. Your balls will do fine. Try once a week to feed them for a month, then switch to offering ever two weeks for the duration of there off feed. Eventually they will eat.