More about Fasting & Abstinence
The Catholic Church has two official forms of penitential practices: fasting and abstinence. These are so important that they’re one of the precepts of the Catholic Church.
Fasting is reducing the amount of food you eat below normal levels. Specifically, on fast days you may eat one full meal and two smaller meals, but those two smaller together should not exceed the amount of the normal meal. Snacking is also prohibited on fast days.
All Catholics age 18 to 59 are required to fast on Ash Wednesday and Good Friday. You are excused from fasting if you have a legitimate need to eat a normal amount of food on fast days. This includes:
Abstinence means not eating meat (fish is not considered meat in this case). All Catholics 14 and older are required to observe abstinence on these days:
Note that the duty to perform the tasks of your state in life takes precedence over the law of fasting in the precepts of the Catholic Church. If fasting honestly causes you to be unable to fulfill your required tasks, it is uncharitable to fast — the law of fasting would not apply in this case. (Consult with a priest if this is a concern to you.)