birth control
"I'm 31 with two kids and I always had regular periods.  I was on the pill for many years and decided to try the Depo shot.  I had some spotting but my period completely stopped after the 2nd shot.  It was very nice not having a period and taking a pill every day.  I didn't start gaining weight until the 2nd shot, and I felt hungry all the time!  I've always been a small person and maintained my weight without diet even having 2 kids.  I had 3 Depo shots total and went back on the pill because my weight kept going up.  I gained 10 lbs and haven't been able to get rid of it since."