birth control
"I gained 20 lbs on Nexplanon over the course of a year and a half, gaining 10 of those during the last 3 months while dieting. When I had it taken out I lost 4 lbs during the first week. I stopped gaining weight and after a couple months my body was back to normal and I was able to lose another 6 lbs (so far).

Not everyone gains weight and I also gained weight very easily during pregnancy. I suspect those two responses may be related. It seems like it would be a great option for lots of people, but beware of this side effect. It's not good for your heart to carry around extra pounds. Good luck!"