Sometimes this fear can extend to IUDs, also known as intrauterine devices. But there’s no evidence these small T-shaped devices, which a doctor inserts into your uterus to prevent pregnancy long-term, will make you get heavier.
“My experience is completely that weight gain is not an issue with [IUDs],” says Henry Dorn, MD, an OB/GYN in private practice in High Point, NC. “The studies basically show that there’s less than 5% [of IUD users] who show any weight gain, and it’s generally a little water weight.”
Even with hormonal IUDs like Mirena, which emit progestin, so little of the hormone gets into your system that any effects on weight are minor, he says.
The progestin in hormonal IUDs thickens the mucus in your cervix to block sperm from reaching an egg. It also thins the lining of your uterus so it’s harder for any sperm that does get through to implant. The device can work and remain in the uterus for 3 to 6 years. A copper IUD uses the metal’s properties instead of hormones to stop most sperm and prevent any that get by from implanting. This type of IUD can stay in your uterus (and keep working) for much longer, up to 10 years.
Weight Gain Not Listed as IUD Side Effect
The IUD is a LARC, which stands for long-acting reversible contraception. Like birth control implants, the matchstick-sized rods a doctor inserts into your upper arm, the IUD works really well. Fewer than one in 100 users of either method will get pregnant in the first year.
Both IUD types work about equally well to prevent pregnancy. They can cause similar, minor side effects for some people, Dorn says, like headaches and changes to your skin, hair, or mood. You might have heavier periods on the copper IUD.
Lists of possible IUD side effects don’t include weight gain. Also, a 2013 study by the American College of Obstetricians and Gynecologists (ACOG) reported that among LARC users, women who used implants and shots were more likely to report weight gain than those who used copper IUDs.
According to the ACOG, LARC methods work 20 times better than birth control pills; the patch, which releases hormones through the skin; or the vaginal ring, which you need to replace every month.
“There is no perfect birth control,” Dorn notes, “but [IUDs] are the best we’ve got.”
It also might be the easiest. “It takes 30 seconds to put in, and 5 seconds to take out,” he says.
Other Things Can Bring Weight Gain
Even when people report weight gain, Dorn says it’s important to think about other factors that might play a role. Sometimes it’s merely your stage of life. For example, if you start using an IUD before your body fully matures, you might think normal body changes result from the IUD.
“A lot of it is timing. A lot of it is, it coincides with the normal weight gain of maturity,” Dorn says.
You can stop the birth control as easily as you start it, too. If you decide you want to get pregnant, or otherwise don’t want to use the method anymore, you only have to go to your doctor or other medical professional to have it removed.
IUDs Can Help With Other Conditions
Dorn also prescribes the IUD as treatment for women who have heavy periods. He cites the number of sanitary pads used as a measure. If you have an IUD, you might have to use 2 to 3 pads less per day during your period, he says.
But such a condition is rare, so don’t let finding a health professional stop you. Check out medical clinics in your area. And while IUDs should be covered by insurance or Medicaid, Dorn says, cost shouldn’t be a barrier either. Clinics often offer a sliding payment scale. “Almost nobody has to pay full price,” he says, which is about $750.
If you’re done having children, Dorn says the best type of birth control is to have the male partner get a vasectomy. “A vasectomy has a zero weight gain for women,” he says.