Breastfeeding

I will be having a baby boy in march. I plan to breatsfeed. I tried with my first but he had lacthing problems and an appitite problem. It didnt work out and I didnt have enough resources. My mother breastfeed my brother but that had been over 18 years ago and she didnt have to much advice or tips. Anyway I have been doing tons of reserach about food for supply and all the things that will help but I want to ask about weight loss while breast feeding. I know you cant diet because you need calories to make milk but does anyone Have any tips for losing weight while breastfeeding without effecting your supply?