The birth control implant, which is known by the brand name Nexplanon, is a long-term birth control method that’s more than 99% effective at preventing pregnancy. It’s a tiny plastic rod that’s placed just under the skin on the inside of your upper arm.

It prevents pregnancy by releasing a continuous low dose of a progestin hormone called etonogestrel. Progestin is a form of the hormone progesterone, which plays a role in your menstrual cycle and pregnancy.

This release of etonogestrel helps prevent pregnancy by thickening mucus in your cervix, thinning the lining of your uterus, and stopping the release of eggs from your ovaries.

While the birth control implant is safe, effective, and super convenient (cheers to not needing to remember to take a pill every day!), some people may experience side effects while using it — including weight gain.

Here are all the deets about birth control implants and weight gain.

The birth control implant has some major benefits. Once it’s implanted under your skin, it does all the work for you. This means no “Oh #$@!%, I forgot to take my birth control pill!” moments. Because the implant doesn’t involve any thinking or planning ahead on your end, it’s often referred to as a “set it and forget it” birth control method.

Plus, it’s more effective at preventing pregnancy than hormonal birth control pills, which are 93% effective with typical use.

But, like other hormonal birth control methods, the implant can cause side effects in some people.

Weight gain is listed as a common side effect of the implant, which means you might gain some weight after getting your birth control implant.

Studies show that, for the most part, birth control implants don’t lead to significant weight gain.

A 2019 study involving 197 teens and young adults who used the implant found that they gained an average of 7.9 pounds in 2 years, while a control group who were not using birth control implants gained an average of 6.8 pounds.

The researchers didn’t find any significant differences in weight gain between the two groups and concluded that long-term birth control implant use does not lead to significant weight gain in young women.

Of the 43 participants who had their implants removed during the 2-year study period, only 6.3% (3 people) said that weight gain was the main reason they wanted to remove the implant.

A 2018 study with 2,963 participants found that implant users had gained an average of 6.6 pounds after 3 years of use. In comparison, users of nonhormonal IUDs gained 2.4 pounds in the same period.

The researchers found that, in comparison to IUD users, implant users gained 1.6 more pounds per year after getting their implant placed if their baseline weight was between 112 and 152 pounds. Those who weighed 154 pounds or more gained 1.7 more pounds than IUD users.

Although weight gain is considered a common side effect of the implant, studies show that the percentage of people who gain weight is pretty low. Some research suggests that 7.7–11.6% of people gain 4–8 pounds over 12 months when using the implant.

While most people don’t gain a significant amount of weight when using the birth control implant, some study findings suggest that factors such as genetics and body weight can influence your susceptibility to gaining weight from the implant.

For example, research shows that people who have variations in the estrogen receptor 1 (ESR1) gene and those who have a higher body mass index (BMI) are more likely to gain weight after getting a birth control implant.

Also, a 2017 study with 127 participants suggests that having the birth control implant placed immediately after giving birth may interfere with the ability to lose any weight gained during pregnancy, especially in people who are overweight or have obesity.

If you find that you’ve gained a significant amount of weight and think it may be related to the birth control implant, talk with your doctor about your options. One benefit of the implant is that you can have it removed at any time and for any reason, including side effects like weight gain.

Eating a nutritious diet, staying active, managing stress, and getting enough sleep are the best ways to reach and maintain a healthy body weight, no matter which type of birth control you use.

Even though the birth control implant may cause weight gain in some people, it’s important to understand that there are many other possible reasons for weight gain, including medication changes, existing health conditions, reduced physical activity, and dietary changes.

If you haven’t changed your diet or activity levels and still find that you’re gaining weight while using the birth control implant, consider talking with your doctor to see whether the implant might be causing your weight gain. They can help you narrow down possible reasons for weight gain and come up with a safe and effective weight loss plan.

You always have the option to remove your birth control implant if you find that it has caused you to gain unwanted weight or if you’re experiencing other side effects that are affecting your quality of life.

If you’ve experienced unwanted weight gain related to the birth control implant, removing it should help you lose any excess weight. The hormone that the implant releases causes weight gain in some people, so removing the hormone from your body should help you lose any weight you’ve gained over time.

If you’ve gained a significant amount of weight, it’s important to be kind to yourself and understand that healthy weight loss takes time.

Instead of turning to unhealthy weight loss methods like super low calorie diets, try using more sustainable and safer methods such as cutting back on ultra-processed foods, eating more protein and fiber, and moving more throughout your day.

In addition to weight gain, the birth control implant may cause a few side effects, some of which are more common than others.

Here are the most common side effects:

  • changes in your period, such as longer or shorter bleeding times and spotting between periods
  • headache
  • vaginitis or swelling of the vagina
  • breast pain
  • viral infections
  • stomach pain
  • painful periods
  • mood changes
  • back pain
  • nausea
  • dizziness
  • pain at the insertion site

The implant also comes with a risk of the following complications, although they are rare:

  • pregnancy due to improper insertion
  • ovarian cysts
  • increased risk of breast cancer, serious blood clots, and liver tumors
  • high blood pressure
  • gallbladder issues

While some of these potential side effects sound pretty scary, most people are A-OK while taking birth control and never experience serious health issues.

If you’re concerned about the possible side effects of the birth control implant, talk with your doctor. They can help you decide which birth control method is the safest and most appropriate option for you.

The birth control implant is a safe and effective way to prevent pregnancy. But, like most other birth control methods, it can lead to side effects in some people.

Some people may experience weight gain when using the birth control implant, although studies suggest that those people usually gain only a small amount.

If you find that you’re gaining weight after getting a birth control implant and you think the implant may be the cause, talk with your doctor about your options.