Does Birth Control Cause Weight Gain?

When the topic of birth control is brought up, I almost always hear someone say “I stopped taking the pill because I was gaining weight” or “I would never go on the pill, I don’t want to get fat!” As I have never taken birth control I had no personal experience and have always wondered whether this was a legitimate side effect. The question made me think of the fact that correlation does not always equal causation. An example of this that we went over in class was the controversy over the belief that vaccines lead to autism. We learned that although there is absolutely no evidence backing up the idea that the vaccines are a cause, people might think it is because babies start to show signs of autism around the same time that they receive certain vaccines. This could also be true of the belief that birth control leads to weight gain. It is possible that many women begin to take the birth control pill as they enter college and also many women gain weight as they first start college. This is an example of a correlational third variable.


Null Hypothesis: Birth control does not cause weight gain.

Alternative Hypothesis: Birth control causes weight gain.

As I began to shift through articles on this topic, almost all of them state that this belief is a myth and that there is no real evidence to back it up. I found a meta-analysis study that includes 49 different studies. Out of all of these trials, none of them found any valuable evidence to say that birth control causes to weight gain. However, that meta-analysis only provided studies for birth control pills and patches and there are other forms of contraceptives. This article in Women’s Health Magazine tells us that a certain injection of birth control can cause a considerable amount of weight gain. Another study on the same injection also resulted in evidence that it leads to weight gain in women.


Figure 3 shows the weight gain over time as the subject receives more of the birth control shots.

Method: Although their is not a lot of information out on the method behind the weight gain caused by the injection, the study above states that it could be due to the shot triggering an increase in appetite.

Conclusion: I think that the most rational way to react to these results is considering risk and reward. If you use the correct type of birth control, it seems as if there is no real risk to gaining weight. Therefore, if birth control is an important preventative measure for a specific person, it makes sense to take it considering there is no real evidence that all birth control leads to weight gain.

7 thoughts on “Does Birth Control Cause Weight Gain?

  1. Alexandra Kaminsky

    Birth control has always been correlated with weight gain and I’ve always wanted to know if it was scientifically true or not. More experiments would really help with proving if it does or does not. However, your studies were good and it was great that you provided the hypotheses just like we discussed in class. Here is an article about weight gain and birth control!

  2. Lucille Laubenstein

    This notion that birth control contributes to weight gain is something which has been passed around for a long time, in my experience at least. This blog does a good job at clearing up some of the confusion regarding that topic. It was helpful that you included both the traditional birth control pill, as well as the injections when analyzing this topic, however those are not the only forms of birth control. IUDs as well as vaginal rings are also popular birth control options. Since they were not included in the blog, I researched to see if there were any studies on whether these methods resulted in weight gain. This is a randomized control trial which looked at the weight gain of women taking an oral contraceptive, compared to those of the vaginal ring. It found that there was no significant weight gain in the participants, and it did not vary by contraceptive type. This study, , which looked at IUD users and their weight gain over a five year period was compared to that of the birth control injection, and found that the IUD users had less weight gain than the injection users.

  3. Lauren Elizabeth Jardine

    The thing about birth control is that while these studies suggest that it may not affect weight gain, it does affect your hormones. With these hormone changes can come mood swings or just over-all emotional changes that may affect your eating habits and indirectly cause you to gain, or lose, weight.

  4. Katherine Yuen

    This post was really interesting, I feel like it’s a pretty relevant topic in many women’s lives. I found this webpage which discusses in some more detail a lot of the issues that concerns that come along with taking birth control, from the benefits such as acne treatment and lowering your risk of anemia. There are also always other kinds of contraceptives that could be better for some people!

  5. Rebecca Jordan Polaha

    I always wondered if this topic was true or not. I feel as though you could have used a couple more sources and studies in this post. A little more explanation on how these trials were done could have helped. I really liked how you brought up the fact that the birth control injections are something they did not consider when doing these trials. It showed you were thinking a lot about the study when researching.

  6. Sabrina Chan

    This is an interesting blog post, but you should consider going into more detail about the specific articles you listed. I like that you made the null and alternative hypotheses easy to see.

    I am less concerned about weight gain and more concerned about birth control’s possible link to cancer. This article here explains that there have been many contradictory studies about whether or not the use of birth control increases the risk of breast cancer. For me, the risk of having breast cancer is not worth the gains of preventing pregnancy because there are other forms of contraceptives. Of course, not everyone else may feel this way.

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