Yom Kippur, literally meaning the "Day of Atonement," is the holiest day of the Jewish year. It is observed eight days after Rosh Hashanah, the Jewish New Year. Many believe that on Rosh Hashanah God determines our fate for the coming year, inscribing all of our names in the Books of Life and Death, and on Yom Kippur, the judgment entered in these books is sealed (hence the holiday greeting "Gmar Chatimah Tova"—May you be sealed for good).
The days between Rosh Hashanah and Yom Kippur are called the Ten Days of Repentance or the Days of Awe. Yom Kippur is, essentially, our last chance to demonstrate repentance so God will seal us in the Book of Life in the upcoming year. As repentance is the theme of the day, Yom Kippur is a day of "self-denial" (Lev. 23-27) with the goal of cleansing ourselves of sins. Prayer services on Yom Kippur are lengthy and solemn, and a 25-hour fast is kept.
To make fasting as easy as possible, and avoid any digestive discomfort as well as excessive thirst, our bodies need to prepare for this fast and eat properly once the fast has ended.
Preparing for the Fast
While hunger pains and weakness are an expected consequence of fasting, one should not dehydrate, faint, or get sick while fasting. There are several ways to prepare for a safe, healthy, and relatively comfortable fast, including watching what you eat and making sure you drink enough water beforehand. Since much of our discomfort during fasting is due to dehydration, it is crucial to drink plenty of water before fasting—and you need to begin a whole week before Yom Kippur to prepare your body for the deficiency. Another liquid your body may miss is coffee—well, actually, the caffeine. If you are a regular caffeinated coffee drinker you should cut back a few days leading up to the holiday to ease the potential for headaches and nausea.
Although the temptation may be to eat as much as you can of the most filling foods, you do need to watch what you eat before fasting. Your pre-fast meals should be low in salt and high in fiber—this will help you avoid feeling thirsty and provide you with sustained energy. It is also important that you eat slowly as eating too fast can cause your blood sugar to spike and in turn make you feel hungry.
Jews traditionally eat the Seudat Mafseket—Meal of Cessation, or pre-fast meal—before the Yom Kippur fast. To ease digestion, you may want to eat a more filling meal in the middle of the day and then a lighter meal for dinner. Many families eat a meat meal for lunch and then enjoy a high-carb dairy dinner directly before the fast. The meat menu can include low-salt vegetable soup, breaded chicken, potatoes, and dessert. The dairy menu might feature an egg souffle, whole wheat bagels with various spreads, and fruit salad.
At the end of Yom Kippur, Jews traditionally share a joyful Break Fast meal with family and friends. Ashkenazic Jews in America and Israel often favor a festive brunch-style menu, like this no-cook bagel and lox brunch. Many Sephardic families prefer to follow a light bread or cake-based snack with a savory meat meal. Whichever the style of meal, it should be something easy to digest so as not to "shock" the system after a 25-hour fast.
Exempt From Fasting
There are situations in which it is considered a greater mitzvah to eat than to fast. If fasting would endanger a person's health or safety, they are typically exempt from doing so. There are also halachic (legal) workarounds for those who may be able to safely get through the day with certain modifications to a traditional complete fast. For example, people with conditions like diabetes, those who require certain medications that must be taken with food, or those who are pregnant may be advised to eat and drink in shiurim—small quantities consumed incrementally.