The Facts About Birth Control and Weight Gain

As women, we gain and lose weight on a daily basis. It’s not unheard of to pack on five pounds during your period, for example, and lose it just as quickly. Well, almost as quickly, depending on how much chocolate you ate while binging Netflix under a heated blanket. 

So, fear of taking something that can further throw your weight out of whack is completely understandable. However, when it comes to your birth control and weight gain, your fears may be misplaced.

Women may stop birth control pill use for fear of gaining weight, or the fear may deter them from even considering it as an option. 

Choosing a birth control method is highly personal, but a choice shouldn’t be made without accurate information at your fingertips. 

And not taking birth control to avoid weight gain is something you should really reconsider.

TL;DR: What You Need to Know

• The pill works by suppressing ovulation, keeping estrogen and progesterone levels artificially high.

• Some believe this “tricking your body into thinking it's pregnant” could result in weight gain.

• Numerous analyses have investigated whether there is a link between the pill and weight gain. Their verdict: a link between birth control and weight gain doesn't exist.

How Your Birth Control Pill Works (and Why You Might Think It’s Causing Weight Gain)

Oral contraceptives work by suppressing ovulation (monthly release of an egg). If you’re not releasing an egg ripe for fertilization, you can’t get pregnant. Your body has a complex system of hormones that regulate this cycle and fluctuate throughout the month. The four main players in this cycle are:

• Estrogen

• Progesterone F

• Follicle-stimulating hormone (FSH) L

• Luteinizing hormone (LH)

Your pill works directly with these hormones.

At the onset of your cycle, you have your period. This happens when levels of estrogen and progesterone are low. A little peak in FSH stimulates what will eventually become a viable egg in your ovaries. Following your period, FSH and LH climb, leading to ovulation, or the release of the egg in preparation for fertilization. 

Once the egg is released, estrogen and progesterone increase and thicken the lining of the uterus, building a comfy home for a baby, in case you become pregnant. 

When the egg isn’t fertilized, all hormone levels drop and the lining of the uterus prepares to shed in menstruation, starting the whole process over again (ugh!).

If you’ve ever heard that the pill “tricks” your body into thinking it's pregnant, you’ve heard a half-truth. When you’re pregnant, progesterone and estrogen levels stay high, suppressing FSH and LH.

Normally, your menstrual cycle and ovulation occur because of peaking levels of FSH and LH. When you’re on the pill, these two hormones are kept at bay, similarly to how they are in pregnancy.

If you think of the birth control pill as tricking your body into thinking it’s pregnant, it’s not a leap of logic to think it could make you gain weight. But, that line of logic would also suggest the pill could lead you to morning sickness, heartburn and much more. It may suppress FH and LSH similarly to pregnancy, but it does not lead to common pregnancy symptoms.

Your Birth Control Pill (Probably) Isn’t Making You Fat

You know when you see a commercial for a prescription drug and the fast-talking lawyers go through all of the potential dangers? 

Yeah, birth control side effects exist, too. If you take the pill, will you experience diarrhea, nausea, weight gain, breast discharge, vaginal swelling, or discharge? Maybe. There is a list of potential birth control side effects, but luckily, they’re not common.

Scientific literature is the best resource when gauging the potential correlation between birth control and weight gain. And, there’s plenty of literature on the topic:

• “Available evidence was insufficient to determine the effect of combination contraceptives on weight, but no large effect was evident,” according to a 2014 clinical review published by Cochrane. For this analysis, researchers looked at 49 different drug trials and failed to find a connection.

• In an analysis published in the journal Obstetrics & Gynecology in 2004, 42 trials were examined for a link between contraceptives—including the pill—and weight gain. And like the Cochrane review above, researchers failed to find a large effect.

• The Journal of Women’s Health published a study in 2014 that examined weight and body composition in both normal weight and obese women using the pill. They concluded the pill is not associated with short term weight or body composition changes for normal weight or obese women.

• A 1995 study published in the journal Fertility and Sterility looked specifically at birth control with low dose estrogen. The researchers found these oral contraceptives were “not associated with overall impact on weight, body composition or fat distribution.”

Science has failed to find a link between oral contraceptive use and weight gain. However, it’s entirely possible you could gain weight on the pill. Let’s say there’s a 50/50 chance you’ll gain 5 pounds in the next six months. And let’s say you decide to start the pill next month. 

Lo and behold, you gain 5 pounds. It could be the pill. But what’s more likely is you were eating more than usual, exercising less than usual, or under increased stress—all actual reasons that you could gain weight.

All that to say, women do gain weight when they’re on the pill. But women gain weight for a lot of reasons, and isolating those reasons can be tricky. We do know that there is no evidence that oral contraceptives cause weight gain. 

But as with any medication change, it makes sense to monitor any side effects with self-awareness, and acknowledge that some symptoms you experience may just be coincidental.

How to Move Forward

Oral contraceptives are well-researched and many women take them without any problems. Don’t write the pill off because you think it’ll make you gain weight—it won’t. But objectively analyze all of your options before making the best decision for your body and life. 

Remember: Not taking birth control to avoid weight gain shouldn’t be the reason you stop or never start. It’s less of an issue than you think.