she won't eat while she's holding. the females will fast until they spit, usually around 3-4 weeks. That's partly why putting a holding female into a separate quarantine/growout tank is beneficial all the way around. When she spits the fry there wont be much trying to eat them, and also the female wont be harassed by the males immediately after spiting to breed again (this is the worst time of aggression in my tank), giving her time to eat and put some weight back on.