• You won't lose weight long-term on birth control, but you could shed water weight with Yasmine or Yaz.
  • Most types of birth control medications have no effect on weight, but there are some exceptions.
  • The birth control shot may make you gain an average of about five pounds in the first year.

If you're thinking about taking birth control, there's a lot to consider when deciding which type is right for you, including side effects. 

Some contraception side effects are well documented and proven, such as nausea or bleeding between periods, especially upon first starting birth control. However, other side effects are more anecdotal, such as the possibility of weight changes.

Here's what you need to know about why some birth control options can affect weight, as well as types of birth control that definitely won't change your weight.   

Can birth control make you lose weight? 

Birth control alone likely won't make you lose weight. "There is not a biological mechanism to explain why non-hormonal or hormonal methods of birth control would cause weight loss," says Alice Sutton, MD, OB-GYN and assistant clinical professor of gynecology and reproductive science at UC San Diego.

However, the myth persists due to peoples' anecdotal reports as well as limited research. For example, the birth control Yasmine or Yaz can act as a diuretic, meaning it makes you need to pee more often than usual. For that reason, you may lose some water weight after starting it but there's no evidence suggesting it will help you lose weight long-term.

And some of the limited research around this topic has similar takeaways. For example, a 2021 study found that participants taking hormonal birth control initially lost weight within the first six months, but then gained that weight back between six and 18 months of continuously taking it. It should be noted that throughout the course of the study, these participants were also on reduced-calorie diets along with supervised exercise programs. 

Additionally, an older 2009 study found that participants who took hormonal birth control had a more difficult time gaining muscle when doing resistance training. Muscle weighs more than fat, so this may contribute to the myth that birth control makes you lose weight. But the study was small and did not imply that birth control could make you shed weight, only make it harder to gain muscle when actively training.

Suffice it to say, it's more likely that weight loss while taking birth control is related to something else, since weight changes are influenced by a number of factors including genetics, diet, exercise, and lifestyle, says Sutton. 

The effect of birth control on weight

There is no solid evidence that most types of birth control can contribute to either weight loss or weight gain. Here's some of the research that shows it has no effect on weight:

  • A 2014 review of 49 studies did not show any strong correlation between taking hormonal birth control and weight changes. 
  • A 2016 review of 22 studies found some limited evidence that participants taking progestin‐only contraceptives may gain up to around four pounds over the course of six to 12 months –– but the authors noted that this type of weight gain can happen over time regardless of birth control use. 
  • A 2011 study that tracked womens' weight over the course of 10 to 20 years found that there wasn't a significant link between birth control and weight gain over time, but rather age and time passing were more likely to result in weight gain.

There are so many factors that can contribute to weight changes and birth control doesn't "seem to make people gain any more weight than they might otherwise have gained over the passage of time," says Sutton.

However, the hormones in birth control can possibly cause water or fluid retention as a side effect, which will likely subside on its own in two to three months, says Heather Figueroa, MD, FACOG, OB-GYN at Loma Linda University Health 

At most, this is only likely to result in a couple of extra pounds, though Figueroa says this isn't very common. If the side effect shows up, persists, and it bothers you, she suggests talking to your doctor about alternative birth control methods. 

Birth control types that can make you gain weight

There is one outlier that may cause added pounds: "The one exception is medroxyprogesterone acetate injectable," says Figueroa. The brand name for this is Depo-Provera, sometimes referred to as the Depo shot or birth control shot.

Pfizer, the manufacturer of Depo-Provera, clearly states in the patient information that during clinical trials, the shot caused two-thirds of the participants to gain around five pounds during the first year, and eight pounds over the course of two years. 

Additionally, a small 2019 study found that compared to the control group, those who got the shot saw an increase in BMI, and gained anywhere between two to 31 pounds. 

The reason why the shot causes weight gain is not completely understood, but Sutton says it may have to do with the formulation of the shots and the concentration of progestin (a form of progesterone) in them versus the concentration found in birth control pills. Additionally, the shot may affect how hungry you get, as progesterone can stimulate your appetite.   

Birth control methods that don't have an effect on weight

If you want to be absolutely sure that your birth control method won't have an effect on your weight, you can opt for non-hormonal methods.

For long-term non-hormonal birth control, Figueroa says you have the option of the copper IUD (ParaGard), which can last for up to 10 years. Instead of hormones, the copper in the IUD prevents pregnancy. 

If you would prefer short-term birth control, Sutton says you can opt for barrier methods (which prevent sperm from getting to an egg) such as:

However, it's important to note that these barrier methods are some of the least effective types of birth control. 

Since all of the above methods do not contain hormones, you don't run the risk of weight gain or loss.

Insider's takeaway

While it can be tempting to make choices based on anecdotal evidence from friends or family, birth control affects every individual differently. Plus, for the most part, hormonal birth control is widely believed to have no significant effect on weight, aside from potentially with the birth control shot. 

"Anyone with questions about finding the right birth control should talk to their doctor and discuss their options. There are many hormonal and non hormonal options, and a good primary care doctor or OB-GYN will help you find the method that is right for you," says Sutton.

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