The Roman Catholic Church has many traditions that date back for centuries. One of the oldest traditions is fasting, especially during the season of Lent. For hundreds of years, the Church has outlined strict fasting laws for Catholics to follow, not only during Lent, but also on every Friday of the year. Today, there are only two required days of fasting--Ash Wednesday and Good Friday--and Catholics are only required to abstain from eating meat on Fridays during Lent.
According to AmericanCatholic.org, bishops of the United States Catholic Church have defined fasting as "partaking of only one full meal." Under this definition, you can also eat a small amount of food at breakfast time and again at lunch (or in the evening, depending on when you choose to eat your full meal), however these other two eating periods combined cannot equal a full meal.
Abstaining is different from fasting, but is also practised during the month of Lent. Abstaining means that you must refrain from eating any meat whatsoever. You can eat animal products, such as eggs, milk and butter, but not meat itself. You are also allowed to eat juices made from meat, such as broth, gravy, consomme, seasonings or sauces.
According to Catholic Canon Law (the rules governing the Church), you must begin abstaining on the required days at the age of 14, but you are not required to fast until age 18. Between the ages of 18 and 59, you must fast and abstain on the required days.
According to the Canon Law, you are required to fast on Ash Wednesday and Good Friday, if you meet the age requirements. Each Friday during Lent, you are required to abstain, but not to fast.
There are exceptions to every rule, even the Catholic Canon Law. Catholics age 59 and older are not required to abstain or fast. You are also not required to fast if you have special health issues, such as diabetes, or if you are pregnant or nursing.