Answer

In Jain tradition, many laypeople observe special restraint or fasting on certain recurring tithis throughout the year. The most commonly observed tithis are:

• Bij – 2nd tithi
• Pancham – 5th tithi
• Ashtami – 8th tithi
• Agiyaras / Ekadashi – 11th tithi
• Chaudas / Chaturdashi – 14th tithi
• Poonam / Purnima – Full moon day
• Amas / Amavasya – New moon day

Among these, Chaudas, Poonam, and Amas are especially important in many Jain communities.

Explanation

Jains may avoid full meals, avoid certain foods, or observe fasting on these days depending on their capacity and family tradition. Common practices include:

• Upvas – complete fasting
• Ekasan – eating once in one sitting
• Beasan – eating twice
• Ayambil – very simple tasteless food once a day
• No green vegetables / no root vegetables – followed by some families on specific tithis

There is also a well-known observance called Pakshik Pratikraman, performed on Chaudas or Poonam depending on tradition.

Spiritual Understanding

These tithis are considered spiritually suitable for:

• reducing attachment to food,
• practicing self-control,
• doing pratikraman and introspection,
• increasing samayik, swadhyay, and japa,
• minimizing violence in daily life.

The purpose is not only to “avoid food,” but to purify thoughts, speech, and actions.

Takeaway

If someone wants to regularly observe Jain food restraint throughout the year, the most important tithis to begin with are:

Ashtami, Chaudas, Poonam, and Amas.

For exact observance, one should follow their Jain sect, family tradition, and guidance of a learned sadhu, sadhvi, or guru.