If u dnt want 2 gain weight i recommend NOT getting one of those implanon rods that get inserted in ur arm. I was 79kg when i got it put in and 8wks later i was 104kg and it took me 9months b4 i lost 1kg and after 2yrs ive only lost 10kgs. Think ur best bet is either condoms or the pill. With the pill as far as i kno the most u can gain is 3-5kg, im on the pill now and i havent gained weight ive actually lost a little bit. Hope that helps u a little =)