Hi when I went on the injection 5 years ago after I kept forgetting to take my pill. I probably put on a few pounds (my mum reckoned that was just me changing in between being 16 & 19) and had blood spotting for about 3 months. then for the rest of the 5 years no periods or anything. I had a break for a year then my periods came back after 6 months. i'm back on it now had my first one in January i've actually lost a bit of weight and had slight light bleeding for a month but OK now. no harm in trying it, only lasts for 3 months it goes so quick. xxx