If you lose it fast, you will probably put it back on again very quickly. I've found that slow and steady gets the weight off and keeps it off. You should probably aim for half to 1kg per week. Also, if you try to starve yourself or reduce your intake too dramatically, you'll lose quite a bit initially and then your body goes into "starvation" mode and you won't lose any more (and it stuffs your body around).
Also, if you are breastfeeding, you will lose gradually anyway - you need enough nutrition to keep you healthy for your baby. Please take it slowly!!
Finished detox but staying on track - and it's paying off!!