A Catholic fast is one regular meal and two small meals in a 24-hour period. Under such conditions of fasting, it does not seem to me that a breastfeeding mother will be under-nourished, much less malnourished to such an extent that it will affect her ability to breastfeed. But, to be on the safe side, she can consult with her doctor to determine if more food is necessary. If a doctor deems it medically necessary, then the fast may be dispensed.
