Should I fast if I am ill, pregnant or elderly?

follow your doctor; the śāstras themselves exempt the ill, the elderly, pregnant women and children, and allow lighter forms.

Dharma never asks you to harm the body that serves it. Vrata digests repeatedly say that the sick, the very old, pregnant and nursing mothers and young children need not fast in the strict way. A well-known verse quoted in these digests lists things that do not break a vow: water, roots, fruit, milk, ghee or havis, a guru’s instruction and medicine.

So take your medicines, eat what your doctor advises, and keep the rest of the vrata: wake early, pray, read the vrata-kathā, avoid anger and quarrels, and give something in charity. That is a complete vrata.

The tradition also allows a pratinidhi, a substitute: a family member or a priest may fast on your behalf while you pray. Diabetic, heart or kidney patients and expectant mothers should never attempt nirjalā or long fasts without medical advice.

Source: verse on what does not break a vow, quoted in Nirṇayasindhu and vrata digests · Medicine never breaks a vrata

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