Birth control is one of the most popular ways to protect from getting pregnant.

Choosing to use contraceptives is an important decision that requires a proper weighing of potential risks and benefits, and you should clearly understand the side effects. Perhaps the most common form of birth control women choose is “the pill.”

Using oral contraceptives such as the pill can lead to common side effects like nausea, breast tenderness, headaches, acne, mood swings, and a lowered libido. But could your birth control pill be causing you to gain weight?

Which Birth Control Method Do You Use?

Studies have shown that one of the most noticeable side effects of chronic use of birth control is weight gain. Of course, not all birth control pills are created equally. The pill that often comes to mind has progesterone and estrogen, and needs to be taken daily.

Another type of pill delivers only progesterone as a way to combat lower libido and other small side effects. This single-hormone pill may come at a price, however, since it can increase your weight by as much as 30 pounds.

It’s not just pills that can lead to weight gain, either. One study in particular, published in the American Journal of Obstetrics and Gynecology, tracked 700 women for three years. Each woman was given her choice of contraceptives, and those who chose Depo-Provera shots (progesterone injections) saw an average weight gain of 11 pounds and two dress sizes even when diet and exercise remained the same. Most of the other birth control options showed some weight gain as well, averaging around three pounds more.

Mechanism of Action for Birth Control

There are three main things that happen when taking birth control. First, your body is tricked into thinking that you are pregnant, so it stops ovaries from releasing an egg and preventing it from being fertilized. Additionally, the mucus between the uterus and vagina thickens, making it harder for sperm to get through to the egg. Lastly, your metabolism is slowed, and this is where the weight gain can begin.

Taking a birth control pill acts like a temporary hormone, so any weight gained should come off when you stop taking it if proper diet and physical activity is present. With shots like Depo-Provera, the weight gained does not fall off as easily, even when you stop taking them.

If you are interested in birth control but do not want to take pills or hormones, there are alternatives. One classic way is by using the fertility awareness method, also called the “natural family planning method.”

With this method, you look for signs of ovulation and track your fertility by keeping an eye out for cervical mucus and a different basal body temperature. During ovulation, your egg is released; this is when you are most fertile. There are approximately seven days during each cycle when you can get pregnant, and many tracking apps are now available on your phone or tablet to help you determine your unique schedule.

In the accompanying audio segment, Sarah Corey, AADP, joins Dr. Holly to discuss the uses of birth control and if it's really causing you to gain (or not lose) weight.