Krispy Kreme
Fat Thursday = doughnut day Saul Loeb/ AFP

Fat Thursday is the last Thursday before the beginning of Lent on Ash Wednesday – and unlike the custom of fasting over Lent, today is specifically allocated for eating as many doughnuts as possible, according to Polish tradition.

Today is known as Paczki Day, the Polish word for doughnut pronounced "poonch-key". Poles love paczki, a deep-fried pastry usually filled with rose or plum jam and covered in dusting sugar. In fact, they're so popular that millions are eaten across Poland on Fat Thursday alone.

Originally, paczki were made ahead of Lent to use up lard, sugar, eggs and fruit in the house, because it was forbidden to eat them during the upcoming period of fasting.

The tradition of eating the doughnuts has continued to this day, although most people choose to buy paczki rather than make them. It's also considered good luck to eat them on Fat Thursday.

Paczki have been popular in Poland since the 16th century, although the recipe has evolved to make the pastries less dense, spongier and lighter. Prior to the 1700s, the doughnuts would have been filled with pork fat and fried in lard.

The pastries are so popular that there are Polish proverbs about them, including: "Those who don't eat a stack of pączki on Fat Thursday will have an empty barn and their field destroyed by mice."

Other Polish paczki saying are equally as concerning: "If you don't eat at least one doughnut on Shrove Thursday, you will no longer be successful in life."

In the United States, cities with large Polish communities such as Boston, Philadelphia, New York, Chicago and Detroit celebrate Paczki Day on both Fat Thursday and Shrove Tuesday, which falls on Tuesday 28 February this year.