Fasting is a ritual practiced by all religions.
For Christians, it happens during Lent, the 40 days leading up to Easter when many abstain from eating foods of their choosing to emulate the time Christ spent in the Judean desert. For Muslims the daily fast during the month of Ramadan is more about purification than penitence. The fast is broken nightly at iftars, gatherings where the feasting and socializing are as important as the fasting that precedes them.