Every day we encounter estrogen and estrogen like compounds in our environment. It comes from plastics, hormones given to livestock and even in our tap water from farm runoff and from human waste water. Those thing are hard to avoid. When we intentionally add extra estrogen through the use of medication such as birth control pills and birth control implants, the problems can be greatly magnified.
I have read many articles recently regarding how the amount of estrogen in birth control pills is very low and that studies show that they do not cause weight gain but, my experience with patients in my office is quite different.
Two patients come to mind. The first was a very fit women in her late forties who was given BCPs to balance out her cycle. Over two months her weight increase over twenty pounds. Nothing else changed in her lifestyle or diet. The second women was 25 and had been a high level athlete in college and was very fit and very lean. After college she went out into the work world and gained a bit of weight. I saw her recently and found her to be quite slim again. When I asked her what she did to lose the weight she told me that she had done nothing except to go off of her birth control pills.
Regardless of the studies one thing is clear to me. If you are using any medication and your weight increases you should question the prescriber of your medication about alternatives.