birth control
"I have always been on a diet and on regular exercise (about 2 hours a day). I stopped dieting for 5 months (precisely the first 5 months I had the implant), and I gained 12 pounds in that time even with the constant physical activity. Even now that I have started dieting again it seems impossible to lose the pounds I gained and even more the fat in the abdominal zone. I have tried hypocaloric diets, cardio workouts and still I can't get rid of them. 
Not to mention the devilish mood swings and headaches.

Of course it works as a contraceptive but agh, WEIGHT GAIN."