I still find it OUTRAGEOUS that people even ask or consider this. It's a no brainer. Plain common sense that you are cleansing toxins out of our system when you fast and no if and or buts about it, these toxins are going to get passed on by the breast milk. The lax tea will give your child diarhrea!!
Balanced diet and regular exercise!!!! Two things that both you and your child will benefit from.
Use the forums search function and you'll find lots of info. There simply is no reasonable "intelligent" rationale or argument for breast feeding when fasting, period.