What Causes Weight Gain During Your Period? 2 Ob-Gyns Weigh In

There's a lot happening in your body — and your mind — during your period. With that, it's easy to wonder if you're the only one going through certain changes that are completely throwing you off during this time. Case in point: Weight gain during your period.

As if dealing with cramps and bleeding isn't enough during your period, you may also notice unexpected weight gain, too. And it's not just you: "This is very common," says Christine Greves, MD, an ob-gyn at the Winnie Palmer Hospital for Women and Babies in Orlando, Florida.

One study found that women tend to weigh a pound more during their period compared to the first week of their cycle, but Dr. Greves says your weight can jump up to five pounds during this time.

So what's behind weight gain during your period and when does period weight gain go away? Also, to help you mentally prepare, when does period weight gain start? Ahead, ob-gyns break it all down.

There are a few things that could be behind weight gain during your period, and a lot of them are out of your control.

During your period, your body experiences fluctuations in estrogen and progesterone levels, which can throw a few things in your body out of whack. That "can lead to water retention, which may contribute to bloating and a temporary increase in weight," says Meleen Chuang, MD, clinical associate professor in the Department of Obstetrics and Gynecology at Family Health Centers at NYU Langone. In fact, research has found that water retention is one of the biggest causes of weight gain during your period.

There's actually a hormonal reason why you may crave chips, ice cream, and other comfort foods during your period. "Progesterone can stimulate your appetite," Dr. Greves explains. "That hormone peaks about a week before the period starts, which is when the munchies might begin." If you started eating less healthy than usual in the lead-up to your period, you may find your jeans fitting a little tighter during your actual period.

It's hard to feel motivated to hit the gym when you're dealing with cramps and bloating. "Some women may skip their regular workouts or physical activity during their period due to discomfort, which can result in reduced calorie burn and potential weight gain," Dr. Chuang says. Of course, this isn't a guarantee that you'll gain weight, but it could be a factor.

Let's back up a moment. Your menstrual cycle is broken up into different phases. The first half is known as the proliferative or follicular phase. This is when your ovaries start making more estrogen to make your uterine lining thicker. The second half is called the luteal or secretory phase. During this time, a follicle, which is a small, fluid-filled sac in the ovary, bursts and releases the egg. That follicle creates a small cyst called the corpus luteum and secretes progesterone and estrogen. But progesterone and estrogen levels start to drop in the lead-up to your period, too.

It's during that luteal phase when period weight gain may start, Dr. Greves says — although everyone is different. You'll likely notice it the most a few days before your period actually starts, Dr. Chuang tells PS.

There's no hard and fast rule on when period weight gain will go away, but it doesn't typically stick around. "A lot of it is temporary," Dr. Greves says. Given that so much of the weight gain is usually water weight, you'll usually shed it by the end of your period, per Dr. Chuang.

Still, if you're grappling with period weight gain and it's consistently not going away when your cycle wraps up or soon after, Dr. Greves recommends keeping track of what you've been eating and drinking during this time, as well as your lifestyle habits during your period, including how much you're sleeping and whether you're getting in regular workouts as usual. "After you've done inventory, keep in mind to avoid certain foods that promote weight gain — for example, high sugar foods — stay hydrated, try to reduce your salt intake, and exercise," Dr. Greves says.

If all of that doesn't help, check in with your doctor. They should be able to offer personalized advice on next steps.

Korin Miller is a writer specializing in general wellness, health, and lifestyle trends. Her work has appeared in Women's Health, Self, Health, Forbes, and more.