Why are there Kreppel (doughnuts) during Mainz Carnival?

As the carnival season heralds the beginning of Lent, people in the Middle Ages used to indulge in hearty meals before fasting. The consumption of fatty and rich foods was recommended to strengthen oneself for the upcoming fasting period. Since Kreppel (also known as Krapfen or berliner) contain plenty of sugar, are sweet, have a sweet filling, and are deep-fried in fat, they were suitable as a treat before entering the fasting season.