birth control
"I'm 33 and just had my first my baby in September. 8 weeks after I had her I had the Mirena inserted. When it was put in, I weighed 162 - I had lost 8 lbs after my daughter's birth. Since then, in the last 5 months since having the Mirena put in, I have not lost a single pound. Not only am I breast feeding, but I'm training for a marathon. I am eating about 1600 - 1800 calories per day (about 500 lower than my normal consumption while training for marathons) and I cannot lose the weight. 
Has Merina made me gain weight? No. But it is clearly a factor in not allowing me to lose baby weight. Needless to say, I'm going to have it removed. I believe there are better alternatives to something that keeps me 30lbs over my normal weight."