Varsitap:
To eat on alternate days, and Upvas on the rest, for a whole year. Thus this fast is very rigorous since it entails a whole year of "tap" with eating no food on alternate days and eating food on rest of the days, while following the prescribed rules like not eating in the evening after sunset, not eating root vegetables (like potatoes, onions, ginger), and various other rules. In Swetamber Varsitap they do Ekasanu as mentioned below alternet days and Upavas on the rest days.