Myths vs. Fact: The Truth About Birth Control and Weight, According to Science

There is no definitive answer to the question of the impact of birth control on a person’s weight. Everyone’s experience is unique. Potential weight changes tend to be hormonally driven and the result of water retention. Some report weight gain of a few pounds that lasts for a couple of months when taking hormonal birth control, though others report no change at all. Those individuals opting for non-hormonal birth control usually report no impact on their weight. When considering your best options for your birth control, it is always important to speak with your gynecologist and/or primary care physician.

Types of birth control

There are several popular options for hormonal birth control.

Commonly referred to as “the pill,” this combined oral contraceptive contains the hormones progestin and estrogen. It allows for a cycle every month or three months. The pill is to be taken at the same time every day. If you are over 35, smoke, or have a history of breast cancer or blood clots, your healthcare provider may advise against this option. When used perfectly, the pill has a failure rate of less than 1%. Sometimes, though, people miss a dose or don’t take it at the right time, which bumps the failure rate to approximately 7%.

A progestin-only pill, called the “mini pill,” is often prescribed for people who are breastfeeding, have a history of lung or leg blood clots, have breast cancer, or cannot tolerate estrogen. It also allows for a cycle every month or three months and is to be taken at the same time every day. When it comes to the mini pill’s efficacy, it’s important to distinguish between perfect use and typical use: As with the pill, with perfect use, fewer than 1% of women will get pregnant during the first year of using progestin-only pills. Typical use has a failure rate of about 7%, which is why it’s important to take your birth control consistently and as-prescribed.

An injection of progestin in the buttocks or upper arm once every three months is often called “the shot.” There is a chance that those receiving the injection may experience more weight gain than those using a copper IUD or oral contraception, according to this study. It has a failure rate of approximately 4%.

A patch can be applied to the lower abdomen, buttocks, or upper arm (though never on the breasts), that releases estrogen and progestin to prevent pregnancy. It is changed weekly and is removed after the third week so the person can have a menstrual cycle during the fourth week. It is prescribed by a physician and has a failure rate of approximately 7%.

The vaginal contraceptive ring is placed inside the vagina for three weeks during which it releases estrogen and progestin. In the fourth week, no ring is inserted so the person can have a menstrual cycle. Its success rate, again, comes down to typical versus perfect use. When used properly, a vaginal contraceptive ring has a failure rate of roughly 1%; when used typically, it has a failure rate of roughly 7%.

The implant is a single rod that is implanted under the skin of a person’s arm where it releases progestin for 3 years. It has a failure rate of approximately .1%.

Can birth control promote weight loss?

Birth control is not designed to be used for weight loss. Any evidence that you hear about birth control’s weight loss side effect is largely anecdotal. Each person responds differently to hormonal birth control. You should discuss both your needs and your options with your physician before you choose the appropriate birth control.

Does birth control cause weight gain?

Birth control does not cause weight gain, though some may experience fluid retention initially when using hormonal birth control (estrogen and progestin). The pill’s evolution since its inception has included a significant reduction in estrogen, which may have accounted for the perception that it causes weight gain. One study calls for improved hormonal contraception counseling from healthcare professionals working with patients to assess their needs. There is plenty of information available about side effects for any kind of birth control. Consult your healthcare provider and be well-informed when you make your choice.

Three additional types of birth control

Barrier methods

The diaphragm or cervical cap is a small cup that is inserted into the vagina to cover the cervix and block sperm. Before intercourse, it is inserted into the vagina with spermicide to prevent pregnancy. See your physician to be fitted for a diaphragm as they come in different sizes. When used perfectly every time you have sex, diaphragms have a failure rate as low as 6%. The typical success rate is around 87%, which means diaphragms typically fail 13% of the time.

There are two types of condom: one is designed to cover the penis and prevent sperm from entering into the vagina to avoid impregnation; the other one is designed to cover the cervix and prevent sperm from entering. Latex condoms also help prevent the spread of HIV and other STDs. Natural and sheepskin condoms prevent pregnancy but do nothing to prevent the spread of STDs. All condoms are typically used with lubricants, though oil-based lubricants like massage oils, baby oil, and petroleum jelly, should not be used with latex condoms as they could easily tear or break. Condoms are available over-the-counter and, when used perfectly, are 98% effective at preventing pregnancy. However, in typical use, condoms are about 87% effective.

The contraceptive sponge contains spermicide which kills sperm. It is inserted in the vagina where it covers the cervix. It works for 24 hours but must be left in for at least 6 hours after intercourse. When used perfectly, the sponge has a failure rate of 9% for people who have never given birth and 20% for those who have. But in real life, this method can be hard to use perfectly. The sponge realistically has a failure rate of closer to 14% for those who’ve never given birth and 22% for those who have given birth.

Barrier methods are highly effective at preventing pregnancy, though most do not prevent the spread of HIV and STDs. If used correctly, the latex condom that is designed to cover the penis has proven to be quite effective at protecting against HIV and STDs.

Intrauterine Devices (IUD)

The IUD is a small T-shaped intrauterine device that is planted inside the uterus by a doctor. It releases a small amount of progestin daily to prevent pregnancy. It stays in the uterus from 3 to 8 years and has a 0.1% - .4% failure rate. There is also a non-hormonal, copper IUD that can remain in the uterus for 10 years and has a failure rate of .8%.

Combination pills

The combination pill neither limits nor causes weight gain. The estrogen in this pill may make you gain a couple of pounds of fluid initially, but within a short period of time your body will regulate and you will return to your normal weight. The differences between it and the mini pill should be part of your discussion with your healthcare provider when you choose the best option for your health and well-being.

Key takeaways

Whether it’s new birth control or something else that leaves you thinking about your weight, the guidance is still the same. Healthy eating, including plenty of fresh fruit, leafy green vegetables, lean meat, chicken, eggs, and low-fat dairy can help with weight management. Limiting excess sugar, and highly processed foods is also important. A regular program of exercise is also great for your health, as is a good night’s sleep, reduced stress, and staying hydrated by drinking plenty of water.

There’s not a lot of evidence to support any concern about weight loss or gain due to birth control. Even if your choice is hormonal contraception, any weight gain is likely to be water weight and will only last a short time. Get all the information before you make any decisions about contraception. Don’t be shy about talking to your gynecologist and/or primary care physician about your birth control. There are plenty of healthy options available to you. Together you can find the perfect one.