Honestly, everyone is different, but I breastfed and pumped (like crazy, I had a little chunker) for the first 2 weeks after I had my son and lost all of my baby weight, plus a few pounds, without exercising. I would wait and see how breastfeeding alone helps you out. You usually can't exercise for about 4-6 weeks after delivery anyway, but even after that, walking, just simple exercises aren't going to affect anything, I'm not sure about the toxins thing, I've never heard of it.