This Is Why You Gain Weight During Your Period (and How to Avoid It)

Updated 07/12/17

Periods come with a whole slew of annoying side effects, including some that start before your actual period. From cramps to fatigue to mood swings, both the week before your period and the week it arrives can be peppered with less-than-ideal sensations and emotions. One of the worst? That dreaded bloated feeling that leaves you super uncomfortable and might even make you reach for your most forgiving maxi dress instead of your favorite high-waisted jeans. And if you step on the scale during that time, you might even be surprised to see that you’ve gained a few pounds. While this period-related symptom is frustrating, for many women, it’s actually totally preventable through a variety of methods. Even if the bloating has already started, there are still things you can do for relief. 

Don't worry, you're not the only one who stresses about PMS weight gain. The good news is that you can avoid it—here's how. 

a bed covered in a spread of boxed baked goods, coffees and fruit

Why Do You Gain Weight Before Your Period?

Like a lot of health issues, the cause behind PMS weight gain and bloating isn’t totally clear, and very often varies from person to person. “We do know that hormonal changes around the end of the cycle can lead to bloating by way of water retention,” explains Anna Druet, a research scientist at Clue. “Other women may experience gas retention and constipation, as progesterone (a hormone involved in your menstrual cycle) can affect the speed of digestion. Some women also experience diarrhea, which is caused by the same hormone-like compounds that make the uterus cramp during menstruation (called prostaglandins),” she explains. All of these GI issues can result in bloating and temporary weight gain.

In terms of water weight, there are three main things that cause you to retain fluids during your cycle, according to Alisa Vitti, creator of MyFloTracker, author of WomanCode, and a women’s health expert. First is that the hormone estrogen can cause salt and water to be retained in your body’s tissues, which usually happens when your body has more estrogen than progesterone. “One way to know if this is your bloating type is if you have pre-existing hormonal imbalances like fibroids, endometriosis, PCOS, or ovarian cysts. If you do, then you have what is referred to as ‘estrogen dominance,’ and during the luteal phase (PMS week), you have your peak levels of estrogen causing the bloating,” she explains.

The second kind of water weight gain is due to the stress hormone cortisol. “You know how when you’re stressed and you step on the scale, you seem to weigh five pounds more than you did the day before? That’s the effect of cortisol for you: It puffs you up due to its antidiuretic function, causing your body to retain sodium,” Vitti says. 

Lastly, magnesium deficiency can cause you to bloat. “The human body is like a battery that runs on special electricity derived from four key electrolytes: calcium, sodium, potassium, and, of course, magnesium,” Vitti notes. Your magnesium level drops in the week before your period, which can contribute to all those nasty PMS symptoms, including bloating.

How Do You Prevent It?

Even though there are many factors at play that can cause menstrual-cycle-related bloating and weight gain, there is one remedy that all experts recommend to keep these symptoms in check before they start: eating healthy. “Consuming a highly-processed diet low in whole foods and high in chemicals and additives will increase your chances of suffering with bloating and weight gain during the premenstrual period,” explains Kyrin Dunston, MD, a board-certified OB-GYN and author of Cracking the Bikini Code.

Druet agrees, noting, “While remedies may be different for everyone, some nutritional changes can likely help to prevent bloating. Though you may be inclined to reach for carb-heavy comfort food, steer clear of salty or processed foods, as these can cause your body to retain water, resulting in bloating.” She says that alcohol and caffeine should get the nix, too, since they can make bloating worse.

And if you’re experiencing PMS weight gain in conjunction with other symptoms, the best thing to do is to get your hormone levels evaluated, says Dunston. “Although PMS is extremely common in the U.S., it is actually not normal. When the hormones are perfectly balanced, PMS should not occur.” With natural hormone regulation treatments and supplementation, which can vary depending on your particular imbalances, you can begin to feel better and kick bloating to the curb.

One thing you should definitely be doing if you’re experiencing PMS weight gain? Hitting the gym. This is especially true if you think your PMS symptoms might be related to stress. “Exercise is a great way to beat stress and decrease levels of the stress hormone cortisol,” explains Vitti. Sometimes, getting your heart rate up can make all the difference.

What Can You Eat to De-Bloat?

Already bloated? Here's what our experts recommend eating to soothe digestive issues and help shed water weight.


“Whenever you’re bloated, your go-to drink should be kefir,” says Frida Harju, in-house nutritionist at Swedish health app Lifesum. This is especially true is dairy products ever give you digestive troubles. “Kefir contains lactase, an enzyme that helps your body digest lactose, which is usually responsible for any bloating, gas, or tummy pain when it comes to dairy products.”


“There are 156 milligrams of magnesium in just one cup of this vegetable, which also has many other health benefits,” says Dunston. “Magnesium helps to relax muscles and may reduce cramping during your period.”


Yup. Chocolate gets the green light. “Just make sure you opt for the 70% dark chocolate, or ones made with organic raw cacao,” Vitti advises. “It’s fairly high in magnesium, with 176 milligrams in a 100-gram serving, which is around half of your daily recommended intake.”


“Avocados are high in potassium, and this is important for muscle relaxation and proper fluid elimination,” says Dunston. She prefers avocados over bananas, which are also high in potassium because they’re lower in carbs. And if you needed an excuse to eat a ton of avocado toast, here it is: “You need a total of 4700 mg of potassium daily, so don’t worry, you can eat it liberally.”


“While this Korean food has a very strong and pungent smell, due to being fermented, it is great for reducing bloating,” says Harju. Packed with probiotics, kimchi will ensure your body is producing plenty of gut bacteria, which will result in a very healthy gut.”


Another mineral you want to pay attention to in order to reduce bloating is calcium. “Broccoli contains 70 milligrams in one serving,” Dunston says. “Have that broccoli with some salmon, which is high in vitamin D, to increase its absorption. Vitamin D has also been shown to improve mood around the menstrual time so this is an added benefit,” she notes.

Nuts and Seeds

“Nuts and seeds contain high amounts of healthy minerals or electrolytes, as well as healthy fats,” Dunston explains. “The minerals will help decrease bloating and healthy fats help to balance out your hormones.”

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