This coming Wednesday, September 15th, at night we will observe Yom Kippur, a day of fasting and atonement. There are 5 prohibitions on Yom Kippur (1) Eating or drinking, (2) washing our body (3) anointing our body (4) having marital relations and (5) wearing leather shoes.
In some cases, fasting is not observed.
For example:
MINORS: a boy or a girl younger than nine years old should not make any type of fast, even for a few hours. When children reach nine years old, they should fast for a couple of hours, if they are in good health. The following year, the parents should encourage them to fast for a little longer, so they will slowly get used to the idea of a complete day of fasting. When the son or daughter reaches eleven years old, they should try to fast for the whole day, if they are in good health. A healthy girl from the age of twelve and a healthy boy from the age of thirteen are obligated to fast.
MOTHERS: After childbirth, during the first three days, a mother should not fast. The same rule applies for the 72 hours after a miscarriage. After the first 72 hours from the day of childbirth until the 7th day from childbirth, if the mother says that she needs to eat, she should eat. After the 7th day she has to fast like everyone else, unless otherwise indicated by her doctor. A woman in labor should not fast.
SICKNESS: A person with a chronic illness like diabetes, etc. or an elder person who is weak because of his advanced age, or someone who is taking an important medication or is undergoing an important medical treatment, should get the advice of a reliable physician to see if he or she can stop the medication, or needs to take eat medication, if the pills can be taken with no water, if he needs to eat in order to take the medication, etc. After discussing the options with a physician, a Rabbi should also be consulted to establish, based on the doctor’s advice, how to eat his food or how take the medication.
Obviously, in a case of a serious risk to someone's health and of course in a life-threatening situation or even when that might be the case (safeq sakana), the fast should be discontinued even if no physician was consulted.
See below how to eat when you need to break the fast.