In Western Christianity, before Lent begins, Fat Tuesday / Shrove Tuesday / Mardi Gras is everyone’s last chance to indulge. Traditionally, the foods that people are supposed to fast from during Lent are cooked up and used up and served. After all, the ancient world didn’t really have refrigeration, so they had to either use it or lose it – throw it out. Pancakes breakfasts, eating pizza – if it uses up flour, odds are it’s on the menu. Carnival is also associated with this time – big parties go on, giving a chance for people to go wild. Carnival comes from the Latin words ‘Carne vale’ or ‘farewell to meat/flesh’.
Ash Wednesday is the first day of Lent, the start of the season of fasting and prayer. During mass, the ashes from the palm fronds that were blessed the previous year are used to mark believers with a cross on their foreheads. The priests will say either: “You are dust, and to dust you shall return.” or “Repent, and believe the gospel.” Ashes serve as a visible symbol of penance and a reminder of our mortality.
Fasting doesn’t mean that believers must not eat at all, rather they are permitted to eat one normal meal and two smaller meals that do not add up to the same size as the larger meal. Snacks are not permitted. There are some exceptions to fasting, small children, pregnant women, and elderly men and women are not required to fast as it would be dangerous to their health. Also, believers are to abstain form eating meat on Fridays, but they can eat fish. Throughout Lent, believers fast in this manner, however Sundays are exempt from fasting as they are not as a part of Lent.
credit goes to the source: http://www.catholic.org/