In Hinduism, each day in a week is dedicated to a particular god in the Hindu pantheon. Thursday, which is Brihaspatiwar or Vrihaspativar, is dedicated to Vishnu and Brihaspati, the Guru of Devas. Thurdsay is also popularly known as Gurubar or Guruvar. Yellow is the color of the day. A fast is observed on the day and food is consumed only once. In some areas, people make it a point to visit Hanuman Temple on Thursdays.
Those devotees fasting on the day wears yellow colored dress and offers yellow colored fruits and flowers to Vishnu and Brihaspati. Food is only consumed once and includes Chana Dal (Bengal Gram) and ghee. Basically, yellow colored food is eaten on the day.