In Jain Dharma, 1 upwas (upvās) means:

• Complete fast for one day
• Generally taken as about 24 hours:

- From sunrise to next day’s sunrise, or - In some traditions, sunset to sunset

What is done in 1 upwas?

• No food at all for the whole period
• Water rule varies by tradition:

- Many Śvetāmbars: only boiled water, and only during daylight - Many Digambars: nirjal upvās (no water), unless guru/doctor advises otherwise

• The day should be spent in:

- Sāmāyik, pratikraman, svādhyāy (scripture study), and quiet sādhanā - Careful non‑violence in thoughts, speech, and actions

So, “1 upwas” = one full-day fast, not just skipping one meal.

You can read a simple explanation of Upvās here: