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Does birth control make you gain weight?

Our weight is something that many of us think about, whether it’s feeling the pressure to look a certain way, or out of concern for our health. It’s no wonder that there is some controversy around the topic of whether or not weight gain is caused by hormonal contraception. In this article, we’ll take a closer look at the science behind this subject and what we actually know about birth control and weight gain.

Does birth control cause weight gain?

The answer to this question is complicated, and it may depend on the method you’re using. However, it seems that in most cases birth control likely doesn’t cause weight gain. There’s not a lot of evidence to support the claim that weight gain is a direct result of taking birth control, and research hasn't been able to find a clear link between birth control and weight gain (or weight loss for that matter). 

Still, it’s a very common belief that this is one more side effect of contraception, and many individuals will attest to this happening. So where does the idea that birth control makes us gain weight come from?

There are a few possibilities. One theory is that the hormones in some birth control can cause bloating, which means that the body is retaining water. Bloating is unpleasant – it can also make us look and feel heavier – but it’s usually temporary and isn’t the same as gaining weight.

Another theory is that hormonal birth control could affect appetite. This in turn might lead to changes in weight, particularly if the increase in appetite comes with cravings for sugary or fatty foods. 

Lastly, there’s another theory that the synthetic hormones in birth control could lead to the body putting on more fat – similar to how our main sex hormone estrogen naturally plays a role when developing breasts and bigger hips and thighs during puberty. 

Not every method of hormonal contraception contains the exact same synthetic hormones or even the same amounts of those hormones. Let’s take a look at a few of the most common methods on the market and what the science says about them.

Does the birth control pill make you gain weight?

Birth control pills – specifically combination pills – contain estrogen and a synthetic version of progesterone known as progestin. These prevent pregnancy by stopping ovulation and making your cervical mucus thicker so that sperm can’t easily travel through the female reproductive tract.

Through the years, there have been several studies investigating if the pill causes weight gain. A review article that included over 40 studies concluded that there is no strong evidence to support the claim that the pill makes you gain weight. Generally, participants tended to gain a bit of weight over time but the results didn’t show that it was directly caused by the pill. 

Many of the studies included in the review didn’t have a control group of people using a non-hormonal method, which makes it a bit tricky to know what actually caused the weight gain that the participants experienced. However, in the studies that did have a control group, there was no difference in weight gain between those using the pill and those who didn’t use birth control.

Another study that followed a group of women over a 20-year period found that the pill did not cause weight gain – the only factor that affected weight was age. Both pill users and those who didn’t use any hormonal birth control gained the same amount of weight over time on average. 

These studies both share the outcome that the participants did gain weight while using the birth control pill. Therefore, it’s very easy to understand why we might think that weight gain is caused by the pill even though it’s more likely that these two things simply happen at the same time, and one is unlikely to be caused by the other.

Does the IUD make you gain weight?

There are two different kinds of IUDs – the copper IUD and the hormonal IUD. 

The copper IUD is non-hormonal and works by releasing small amounts of copper into the uterus. This makes the environment in the uterus hostile so that sperm can’t survive, and it also prevents implantation of a fertilized egg cell from happening. 

The hormonal IUD on the other hand contains a synthetic version of the hormone progesterone. It works by making your cervical mucus thicker so that sperm can’t reach the egg, and it can also stop ovulation or make it more irregular.

The copper IUD has not been found to cause weight gain, but when it comes to the hormonal IUD, findings have varied. Some studies found that the hormonal IUD may have a small effect on weight, but when taking other factors into consideration (such as age), it’s not completely clear that the weight gain is connected to the IUD itself.

Does the depo shot make you gain weight?

The birth control shot, or depo shot as it’s commonly called, is an injection that you get every few months that contains synthetic progesterone. The depo shot is one birth control method that has been more clearly linked with weight gain.

 A study comparing the depo shot with birth control pills showed that those using the depo shot gained more weight than those using the pill (the pill was not linked to weight gain). The same was also found in another study comparing the depo shot with the copper and hormonal IUD, where those who used the depo shot gained more weight than those using the IUDs.

Again, it can be tricky to determine how much of the weight gain is actually caused by the depo shot and how much happens because of other factors, but it’s likely that the depo shot can cause a small amount of weight gain at least for some people who use it.

What causes the weight gain we see in the studies?

So if most birth control methods don’t make you gain weight, why do so many of the studies show that the participants gained weight over time? 

There’s no one simple answer to this since weight is something that’s related to many different things. However, we do tend to gain weight as we get older, starting at puberty and continuing during our adult years. This is important to keep in mind when looking at results from studies that follow people who use birth control over several years – even if they do gain some weight, it’s not necessarily because of the birth control so the studies should factor in that age is also linked to weight gain. 

Most of us will experience changes in our weight during our lives, for example when our routine changes. We might lose or gain weight when going through a stressful period in life, when starting a family, getting a new job or starting a new hobby – and that’s okay. If you have concerns about weight gain or questions about it in relation to your birth control method, it’s a good idea to talk to your healthcare provider to find out more.

Weight loss after birth control

Because there’s no clear-cut connection between birth control and weight gain, it’s also not certain that you’ll lose weight if you stop using a birth control method. There are a few studies that have looked into whether stopping certain birth control methods leads to losing weight, and the results have been similar to what has been found about birth control and weight gain. 

One study found that stopping methods like the birth control pill doesn’t seem to result in weight loss, but there is evidence to suggest that stopping the depo shot can make you lose some weight (the depo shot is also the only method that’s been directly linked to weight gain).

Every person has a unique experience and weight can be influenced by many things in life. When it comes to losing weight, changes to diet and exercise are of course the most commonly mentioned solutions, but it’s important to keep in mind that many other factors will affect our bodies. If you are ever concerned about your weight, talk to a healthcare professional to learn more.

Want to go hormone-free and learn more about your body?

It’s normal to keep an eye on possible side effects when deciding which birth control method to use, what’s important is that you have access to all the info and the options available to find the best method for you. Here at Natural Cycles, we are passionate about making sure that you have the knowledge you need to make informed decisions about your body. 

If you are interested in trying non-hormonal birth control and curious to learn more about your body, why not see if Natural Cycles hormone-free birth control could be right for you?

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Written By

Freya Eriksson

With more than three years of experience in the field, Freya Eriksson specializes in writing about the latest research into fertility and reproductive health. She is passionate about shining a light on under-researched topics such as contraception and planning pregnancy. Freya holds a Master's degree in Linguistics and lives in Stockholm, Sweden.

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Scientifically Reviewed

Jack Pearson

Dr. Jack Pearson is a previously HCPC registered Embryologist with a PhD in reproductive medicine. Prior to joining Natural Cycles leading Medical Affairs, he worked for more than 10 years in a clinical setting working at some of the busiest fertility clinics in the UK. Today he spends most of his time working with experts at the world’s leading institutions to carry out important research with the vision to further the field of female health. He earned his PhD from the University of Sheffield specializing in Sperm Metabolism and currently lives in London.

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