Hi, I've been low carbing since just after Easter and have lost over 2 stone. I started when my DS was 7 weeks old and he's thriving. I eat loads of vegetables and drink around 5 litres of water a day. I haven't had him weighed for a while, but at 15 weeks he's nearly out of size 3-6 month clothes so he certainly hasn't suffered from this way of eating!
I'm going to start next week. From what I've read it's recommended to avoid ketosis as a precaution and to take a supplement. Breastmilk quality won't deteriorate much if your diet is inadequate but it will affect your health if you aren't getting enough nutrients. You also need to make sure you're getting enough calories or your milk supply can dwindle.