צוֹם מוֹעִיל
Note: Patients with chronic disorders such as heart disease, diabetes, ulcers, and hypertension (high blood pressure) and those who take medications regularly should consult with their doctors about whether fasting could present a danger to your health. Some may be advised only to drink or to eat only small quantities of food every half hour or so. All fasts should be immediately discontinued if there is any medical danger to health. Pre-Bar-Mitzwah children are exempt as are pregnant and nursing women and the elderly under certain circumstances. The Israel Cancer Association recommends that cancer patients not fast without approval from their physicians. Association chairman Prof. Eliezer Robinson says that fasting could cause considerable discomfort in cancer patients, who need a lot of liquids to alleviate side effects of chemotherapy.
Tisha be-Av and Yom Kipur are 24-hr., eve-to-evening fasts. All other fasts are dawn-to-dusk fasts from food and drink. Medical considerations take precedence over all fasting. Children under the age of בר/בא-מצוה aren't required to fast. However, for several years approaching the age of הוצמ תב / רב, children should be assigned a gradually increasing responsibility for fasting the entire day, realizing this goal by the age of בר/בת-מצוה.
If the צוֹם occurs on שבת, the fasting is delayed until the first day of the week. Only in the case of Yom Kipur is the fast observed even on שבת.
(Excerpts from article by Judy Siegel for Yom Kipur, Jerusalem Post, 2003.10.05 have been combined with a 1999 Jerusalem Post article)
One should seriously curtail drinking coffee or other beverages with a significant amount of caffeine (such as cola, tea or cocoa) to minimize headaches. It's also advisable for everyone to drink more than the usual amount of water — about 12 or 13 glasses — during the day before a fast.
Aliza Palnet, a clinical dietitian at the Rambam Medical Center in Haifa, recommends, for those with no diabetes or other medical problems, that on the day before a fast people eat pasta, potatoes, couscous, corn, rice, pulses, bread, and other complex carbohydrates. Medical experts and clinical dietitians at Kupat Holim Clalit also warn against eating salty food products such as potato chips, pickles, and salty cheese before the fast — they would lead to dehydration and thirst.
On the eve of a fast, many prefer to eat two meals — one at noon and the other an hour before the fast begins. The menu for the noontime meal should be fish, consommé with noodles or soup, nuts, a small portion of meat or chicken.
The pre-fast meal should be rich in complex carbohydrates, such as pasta, rice, and potatoes. These reduce the feeling of thirst, provide a feeling of fullness, and reduce urine production. Don't each much protein, but a serving of chicken or fish is desirable. You may include, too, a small salad or vegetable, and cooked fruit but not something that is very sweet. Don't eat much fat — any consumed should be mono-unsaturated fats such as that from avocado or olives. It is wise to limit or avoid consumption of butter, cream, margarine, yellow cheese, fat meats, and hot dogs. Experts recommend that you avoid consuming carbonated beverages, salty or spicy foods, and coffee and tea (these speed up the loss of fluids).
During the fast, stay out of the sun to avoid loss of fluids and don't exert yourself. If you feel unwell during the fast, discontinue fasting; particularly if you manifest symptoms of dehydration. (You should learn and know these symptoms in advance of the fast.)
Break the fast by drinking sweet tea and eating a slice of whole wheat bread with honey or jam. Then wait forty-five minutes to an hour after breaking the fast before eating solids, so as not to shock the digestive system. Then one can eat a balanced meal with protein, carbohydrates, and vegetables. The first meal after the fast should be comprised of light foods, followed by complex carbohydrates such as mashed potatoes. Fried foods are not a good idea. When you start a meal, don't eat too much or too quickly, or you could wind up with both a stomachache and a headache, and even feel faint. After eating, it's best not to exert yourself, the dietitians advise.