Unless a fast-free period has been declared, Orthodox Christians are to keep a strict fast every Wednesday and Friday. The following foods are avoided:
Meat, including poultry, and any meat products such as lard and meat broth.
Fish (meaning fish with backbones; shellfish are permitted).
Eggs and dairy products (milk, butter, cheese, etc.)
Olive oil. A literal interpretation of the rule forbids only olive oil. Especially where olive oil is not a major part of the diet, the rule is sometimes taken to include all vegetable oils, as well as oil products such as margarine.
Wine and other alcoholic drink. In the Slavic tradition, beer is often permitted on fast days.
The Church has always exempted small children, the sick, the very old, and pregnant and nursing mothers from strict fasting. While people in these groups should not seriously restrict the amount that they eat, no harm will come from doing without some foods on two days out of the week — simply eat enough of the permitted foods. Exceptions to the fast based on medical necessity (as with diabetes) are always allowed.