In Jainism, fasting (upavās/tap) is a sacred austerity. When done with the right intention (bhāva), this is what happens:

• Spiritually

- Stops new karmas from entering (samvar) and helps shed bound karmas (nirjarā). - Softens the four passions—anger, pride, deceit, greed—so the mind becomes calm and compassionate. - Strengthens vows, mindfulness, and equanimity; supports right conduct and study.

• What counts as fasting in Jain dharma

- It is one of the six external austerities (bahya tapas) among the twelve tapas described in the scriptures. - Forms include: complete fast (anashana/upvās), eating once or twice with restraint (ekāsan/biāsan), āyambil, giving up taste (rasa‑parityāga), limiting intake, etc. - Always take pachchakkhān (vow), keep boiled water rules as per your maryādā, and pair the fast with pratikraman, svādhyāy, samayik, and kāyotsarga.

• How to keep it pure and safe

- Do it with humility, not for show. Maintain ahiṁsā in thought, word, and deed. - If unwell, elderly, pregnant, or on medication, choose milder tapas after guidance. - Break the fast (parṇā) properly and calmly, without attachment or pride.

• Tradition notes

- Both Śvetāmbara and Digambara accept fasting as central to the 12 tapas. Practices and festival calendars differ (e.g., Paryushan’s 8 days; Das‑Lakshan’s 10 days) and water/ timing rules may vary. Follow the maryādā of your sangh.

For simple guides:

• Why and how fasting purifies karma
• When to take pachchakkhān for upvās
• Fasting during Paryushan (practical tips)