Seven, fasting does not mean you cannot eat
nothing, just the forbiden(?) foods, meat, oil etc.etc.....there is
alot other thing you can put in your mouth while fasting and you are deffinately not going to get sick

In my country(which is orthodox christian) there are 4 major fasts, and all 4 of them have different food restrictions. Older people and people that are ill, can consult with their priest and can fast lets say...not so strictly