Nahai Khai is the first day of Chhat puja festival. In 2013, Chhat Nahai Khai date is November 6. Nahai Khai means to take bath and to eat.
Devotees perform early morning ritual bath (Suryodaya Purva) in the holy river of Ganga. Some special recipes are prepared on Nahai Khai day.
Chhath Nahai Khai Puja day is also known as Lauki Bhat because on this day a special recipe called Lauki is prepared and offered to Surya bhagwan. Nahai Khai or Lauki Bhat is the first day during 4-day Chhat pooja.
Kharna vrat, Chhat Sandhya Argh, Chhat Suryodaya Argh are celebrated on second, third and fourth day respectively during Chhath Puja.