Shasti Viratham is mainly done for Lord Muruga. Usually Kanda sasti will falls in tamil month of Aippasi. Normally devotees fast during the 6-day period. Devotees who follow the viratham will take food once a day means either in the morning or evening or night, they will take food only once and that too only tiffen not a meal. Devotees can take water, milk or fruit juice (Only liquid food)
For the 6-day period they have to say "Kandha Shasti Kavasam", daily twice morning and evening. Devotees need to visit Lord Muruga temple at least daily once for the 6 days. The fasting ends on the Sixth day and on the sixth day they have to visit Lord Muruga temple.
Above listed is the procedure to follow during Shasti Viratham. But the people who are not able to be in fasting can avoid Non-vegetarian food instead of fasting.