I'd personally get her to stop it . I think it's ALOT on the body and if she was already abit off colour beforehand .
I tried to do it every year from year seven to year ten and im ashamed to say I never made it past 24 hours max. Even with barley sugar I just felt terrible . Terrible physically , terribly mentally because I couldnt finish yet some people didnt have the choice to just go get something to eat like I did :-(
What a beautiful little soul though for wanting to stick it out .