In a Jain upvas (fasting day), people usually follow a vow to eat less or certain kinds of foods to cultivate self-control and compassion. What you may eat depends on your specific vow and tradition (Digambar vs. Shwetambar) and can vary from household to household.

Common patterns:

• Some fast by eating only one light meal a day or by consuming only fruit, milk/dairy, nuts, and non‑root vegetables.
• Many avoid root vegetables (like potato, onion, garlic, carrot) and may also limit grains or cooked foods. Some stricter observers avoid grains entirely and eat only fruits and dairy.
• Others practice nirjala or partial fasts, where even water or certain foods are restricted.

Because practices differ, it’s best to follow the vow you’ve taken and, if unsure, check with your guru, family tradition, or a trusted Jain center for guidance on what is allowed on your upvas.

If you’d like, tell me which tradition you follow (Digambar or Shwetambar) and what vow you’ve taken, and I can give more specific guidance tailored to that practice.