Weight Gain During Period: Causes, Treatment, and Prevention

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Your periods can come with a whole slew of annoying side effects, including some that start before your actual period. (PMS, anyone?) The weeks surrounding (and during) our periods are often peppered with some, well, less-than-ideal sensations and emotions—from cramping and fatigue to mood swings, headaches, and nausea. And that's not to mention the dreaded bloat: Not only does a puffy midsection unceremoniously signal that your period is coming (and make you reach for your most forgiving maxi dress instead of your favorite high-waisted jeans), but it also indicates that you may be bound for some weight gain, too.

But whether your bloating and weight gain are symptoms of PMS or if they seem to creep up while you're already on your period, they're relatively preventable. Ahead, we spoke to a nutritionist, science writer, and OBGYN to get their recommendations. So whether you're experiencing PMS or your period is already in full swing, learn about effective ways to relieve bloat and period-induced weight gain—and minimize symptoms for good.

Meet the Expert

  • Anna Druet is a science writer, researcher, and was formerly Clue’s Science and Education lead. She specializes in women's health topics, particularly reproductive issues.
  • Kyrin Dunston, MD is a board-certified OBGYN as well as a Life Mastery Consultant. She is a member of the Institute of Functional Medicine (IFM) and the American Academy of Anti-Aging Medicine (A4M).
  • Dietitian Frida Harju-Westman is an in-house nutritionist at the health app Lifesum.

Why Do You Gain Weight During Your Period?

Like a lot of health issues, the exact causes of PMS weight gain and bloating aren't that clear, and very often, they vary 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 the period and ovulation tracking app 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 lipids (called prostaglandins) that make the uterus cramp during menstruation,” she explains. Each of these GI issues can result in bloating and, thankfully temporary, weight gain.

When extra water builds up and is then held by the body, it's referred to as water weight. And according to Alisa Vitti, a functional nutritionist, women’s hormone expert, and author of WomanCode, there are three main causes of fluid retention during the menstrual cycle.

What Causes Period Weight Gain?

According to the experts, there's no one cause of bloating and weight gain during your menstrual cycle. However, there are a few common processes that may lead to these symptoms. Read on for the most frequent causes.

Estrogen Dominance

The first is that the hormone estrogen can cause salt and water to be retained in the body’s tissues, which usually happens when estrogen outweighs the progesterone level in the body (aka "estrogen dominance").

One way to know if estrogen dominance is what's causing your water retention and bloat is "if you have pre-existing hormonal imbalances [that have resulted in] fibroids, endometriosis, polycystic ovary syndrome (PCOS), or ovarian cysts," explains Vitti. So if you're feeling bloated during the luteal phase (the two-week period between ovulation and before the start of menstruation) and suffer from any of these maladies, you can reasonably assume that peak estrogen levels are causing the bloating.


Whenever we're stressed out, cortisol (the "stress hormone") is released by the body's adrenal glands. When cortisol levels increase, the body becomes resistant to insulin, which results in increased blood sugar and weight gain, too.  “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," asks Vitti. "That’s the effect of cortisol," she explains. "It puffs you up due to its antidiuretic function and causes your body to retain sodium."

Magnesium Deficiency

The week before your period, magnesium levels drop and can contribute to all those uncomfortable PMS symptoms, including bloating. “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. Magnesium supplements have been shown to reduce stress and improve insulin resistance. Lower-than-normal levels can also cause constipation (and thereby, bloating), fluid retention, and gas during your period.

How to Minimize Bloating During Your Period

Although there are many factors at play, there are some things you can do to manage weight gain and bloating to due PMS.

Healthy Eating

Virtually every expert recommends eating healthy to keep symptoms in check. “Consuming a highly-processed diet low in whole foods and high in chemicals and additives will increase your chances of suffering from bloating and weight gain during the premenstrual period,” explains Kyrin Dunston, MD, a board-certified OB-GYN.

Avoid Salt

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 you should avoid alcohol and caffeine since they, too, can make bloating worse.

Evaluate Hormone Levels

If you’re experiencing PMS weight gain along with other bothersome symptoms, then have your hormone levels evaluated by a doctor, says Dunston: “Although PMS is extremely common in the U.S., it isn't actually normal; when the hormones are perfectly balanced, PMS should not occur.” Natural hormone regulation treatments and supplements, which vary depending on one's particular imbalances, can help you feel better and kick bloat to the curb.


If you think your PMS symptoms might be related to stress, then hit the gym. “Exercise is a great way to beat stress and decrease cortisol levels,” explains Vitti. Sometimes, getting your heart rate up can make all the difference.

Is It Possible to Avoid Any Weight Gain During Your Cycle?

It’s important to note that weight gain and bloating from hormonal fluctuations cannot always be avoided. Natural body mass and weight changes are part of life, but they can be minimized with the above tips and methods. Also, if prevention is no longer your main concern because you're already bloated, our experts recommend eating these seven foods to soothe the digestive issues and minimize symptoms.

avocado and spinach

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“Whenever you're bloated, your go-to drink should be kefir,” says dietician Frida Harju-Westman, an in-house nutritionist at the Swedish healthy living app, Lifesum. Drinking kefir—fermented milk with the consistency of a thin yogurt—is especially helpful if dairy products give you digestive troubles. “Kefir contains lactase, an enzyme that helps your body break down 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 spinach, says Dunston. This "helps relax muscles and may reduce cramping during your period.” Bonus: Magnesium is also said to decrease PMS symptoms such as irritability and headaches, too.


Yes, chocolate has made the cut. “Just make sure you opt for 70% dark chocolate or treats made with organic raw cacao,” Vitti advises. (And be sure it's not loaded with sugar, which causes inflammation.)


Not only do avocados promote brain health, but they're also high in potassium, with 354 mg per half-cup serving, which research has shown to decrease sodium levels and increase urine production, thereby helping to reduce water retention and improve period bloating. Dunston prefers avocados over bananas (a medium-sized banana contains 422 mg of potassium) because they’re lower in carbs.


Kimchi is a savory Korean side dish that's primarily composed of salted napa cabbage and spices. “Because it's fermented, it has a very strong, pungent smell," says Harju-Westman, "but it is great for reducing bloating." And, since kimchi is chock full of probiotics, it also promotes a healthy gut.


Many cruciferous veggies, such as broccoli, are rich in calcium, which research has shown decreases PMS fatigue and depression. To increase the body's absorption of calcium, says Dunston, “Have that broccoli with some salmon, which is high in vitamin D." Calcium-and-vitamin-D supplements, Dunston adds, have been shown to improve mood and reduce the severity of PMS symptoms, such as diarrhea, constipation, fatigue, depression, and bloating.

Nuts and Seeds

Many nuts and seeds are high in B vitamins (particularly B1 (thiamine), B6, and riboflavin), which have been shown to help decrease PMS symptoms such as irritability, fluid retention (weight gain), and bloating, among others. (Think: unsalted almonds, pistachios, and sunflower seeds.) “Nuts and seeds contain high amounts of minerals, electrolytes, and healthy fats,” Dunston adds, “which also help to balance our hormones.”

The Final Takeaway

Weight gain and bloating during your menstrual cycle is a prevalent—and often preventable—symptom of PMS. Experts agree that these issues are frequently treatable with a combination of preventative measures (like good nutrition and exercise) and methods to monitor stress and hormone levels.

At the end of the day, it's also important not to put too much stock in a number on the scale. Being gentle with yourself and understanding the inputs and effects of what is happening in your body during your cycle can help manage the stress of unexpected weight gain or uncomfortable bloating.

Article Sources
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