IUD weight gain?

Jessica
I'm 36 weeks and I'm planning on having an IUD put in 8 weeks after delivery. The 2 choices my dr gave me was the mirena and paragard. I was wondering if any ladies on here have had either one before or have it now and how many of you gained weight from it. I have always been a bigger girl so my weight has always been a struggle for me even with working out and eating healthy. I'm scared I will gain a lot of weight with birth control. I've never been on birth control before so I want to see what experiences you guys have had with the IUD