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Why Do You Gain Weight on Your Period?

Written by
Natalie Krafft
Team Nutrisense
Reviewed by
Heather Davis
MS, RDN, LDN
A person with long black hair and glasses in a yellow top and grey sweatpants, standing in front of a floor-length mirror

Menstruation is a healthy and normal process, but unfortunately, many people experience unpleasant side effects during this time. If you’re a person who menstruates, you may be familiar with feeling bloated or even feeling like you’ve gained actual weight during your period.

Slight weight fluctuations during your period are common, and are mostly related to changing hormone levels during your cycle. But, if you find bloating or water retention to be uncomfortable, there are some things you can try out to alleviate or prevent these symptoms from occurring.

In this article, we’ll break down each phase of the menstrual cycle, how it affects your hormones, and how these factors can lead to temporary weight gain.

Phases of the Menstrual Cycle

Graphic of the Follicular Phase, Luteal phase and Ovulation during the Menstrual Cycle

The menstrual cycle can last anywhere from 25 to 31 days, although healthy cycles are usually consistent. There are two main phases of the menstrual cycle, and each one can significantly impact your hormone levels. Let’s review each phase and its effect on estrogen and progesterone levels to understand how they’re connected to weight gain and bloating.

Follicular Phase

The follicular phase of the cycle starts when you begin menstruating and lasts for approximately two weeks until ovulation begins. During this phase, your body prepares to release an egg for fertilization. As your body prepares to do so, your estrogen levels rise.

Menstruation 

Menstruation is what you typically think of when you hear “period.” It’s the main event of the follicular phase. During this event, the uterus sheds its lining and tissue, or, as most people call it, period blood.

At the beginning of menstruation, your levels of estrogen and progesterone are low. However, estrogen and progesterone levels slowly start to rise towards the end of your period. The shedding process usually lasts between two to seven days, depending on how your unique body works.

Luteal Phase

A woman in grey t shirt and slacks sitting in front of a white cupboard holding her forehead

The luteal phase makes up the remainder of your menstrual cycle. After the egg is released during ovulation, the ruptured follicle that held it remains on the uterine lining.

In this phase,  progesterone levels rise (and are at their highest) in preparation of fertilization. If the egg is not fertilized, your progesterone levels will drop, leading to the shedding of the uterus lining and restarting the cycle.

Ovulation

Ovulation, the main event during the luteal phase, occurs about halfway through the menstrual cycle (although this may differ for different people) and tends to last for 24 hours. During this phase, the mature egg is released from your ovary.

During the ovulation phase of your cycle (or the fertile window), the chances of getting pregnant are the highest. Estrogen will peak just before you begin ovulating, and will begin dropping shortly after.

What Causes Period-Related Weight Gain

While it’s common to see the number on the scale fluctuate a little during your menstrual cycle, it’s important to remember that this is generally temporary. There are many factors that can cause your body weight to rise by a few pounds while on your period.

Let’s get into a few of the most common potential causes of period weight gain.

Hormonal Changes

Torso of a woman in a white top and blue jeans, holding her stomach

The most common cause of weight gain or fluctuation during your cycle is hormonal fluctuations. As we discussed earlier, estrogen and progesterone levels are constantly shifting in preparation for your egg’s fertilization.

Weight gain or fluctuation may occur in some during their luteal phase (a little before the period begins) when progesterone levels rise. High progesterone levels can trigger increased appetite or cravings, which we will discuss in further detail below.

Premenstrual syndrome, or PMS — a syndrome that involves experiencing many unpleasant symptoms before a period like cramping, bloating, cravings, and mood swings — may also be caused by these shifting hormone levels, although these shifts are more significant in PMS. PMS occurs during the last week of the luteal phase, just before menstruation begins.

Bloating and Water Retention

Bloating can be caused by various factors, including gas, gastrointestinal issues, or fluid retention. However, hormonal fluctuations, specifically the changes in progesterone, during the menstrual cycle can lead to bloating or abdominal discomfort.

Fluid retention and bloating can also be caused by a higher salt intake, as some women notice when they’re in their luteal phase. While these symptoms can lead to a few extra pounds showing up on the scale, this water weight is temporary and usually goes away on its own.

Increased Appetite

Woman with hair up in a kitchen eating yogurt

If you find yourself experiencing cravings either before your period starts or during menstruation, you’re not alone. During the luteal phase, progesterone levels peak in your body, which may lead to increased food cravings and overall food consumption.

Other research has found evidence to confirm that women tend to consume more protein and experienced food cravings during the luteal phase of their cycle. Carbohydrate cravings have also been observed to occur during the luteal phase, which can lead to increased energy intake and cause weight gain in some people.

Conversely, estrogen may inhibit appetite. Higher estrogen levels that occur during the follicular phase may lead to fewer cravings at the beginning of the menstrual cycle.

Other Common Symptoms You May Experience During Your Cycle

A woman in white pyjamas sitting at the foot of a bed holding her forehead

Menstruation is a complex process occurring inside the uterus each month. Because of this, it’s not surprising that these hormonal shifts would naturally lead to some symptoms as each phase takes place.

Here are some other common symptoms of PMS you may experience before or during your time of the month. These symptoms may also occur due to the same factors that lead to period-related weight gain, such as changing hormone levels.

  • Mood swings
  • Fluid retention
  • Constipation
  • Abdominal cramps
  • Gastrointestinal issues (although this may indicate an underlying condition; more on that below)
  • Fatigue
  • Headache or migraine
  • Anxiety
  • Breast tenderness
  • Low sex drive

It’s important to remember that everyone’s body is different, and some people may not experience the same set of some or all of these symptoms. If you’re concerned about any symptoms you may be experiencing during your cycle, consult a gynecologist or women’s health specialist for guidance.

How to Combat Weight Gain During Your Period

Temporary weight gain during your period is a common side effect of the menstrual cycle that usually fluctuates back to normal within a few days. However, if you want to limit uncomfortable symptoms such as bloating, there are a few things you can try out.

Exercise

Getting some extra steps in by walking, going to the gym, or moving your body in any way you can are all great ways to increase your physical activity. Studies show exercise may have diuretic properties, meaning it could help you reduce period bloating.

In one study, women who exercised three times a week for 20 minutes were observed to have improved PMS symptoms. Exercise can also be a beneficial treatment for other causes of bloating that are connected to gas or conditions such as irritable bowel syndrome (IBS).

Not only is physical activity beneficial for PMS symptoms like bloating, but it can also help with weight management, support healthy blood sugar levels, and may reduce your risk of cardiovascular conditions.

Stay Hydrated

A woman in a white top drinking water from a bottle

Although it sounds odd, drinking plenty of water can help prevent water retention. It occurs because when you are dehydrated, your body retains water to help keep its water levels optimal.

Staying hydrated is crucial for healthy blood sugar levels, kidney and liver function, metabolism, digestive health, and brain function. If you find it hard to drink enough water throughout the day, here are some dietitian-recommended hydration strategies to follow.

Try Magnesium Supplements and B Vitamins

Researchers have studied the effects of supplementing with magnesium and vitamin B6 together on the symptoms of PMS. Magnesium on its own may help alleviate period cramps.

In one study, researchers investigated the benefits of magnesium and vitamin B6 on period-related water retention, anxiety, and cravings. They found these supplements to significantly relieve these symptoms compared to the placebo group.

If you prefer to consume magnesium through whole food sources, try adding extra green leafy vegetables, nuts/seeds, legumes, or whole grains to each meal.

Track Your Changing Hormone Levels 

Side profile of a woman in an orange top, wearing glasses, looking into a martphone

While some bloating is common during menstruation, significant and persistent weight fluctuations (as well as any other symptoms mentioned previously) may indicate hormonal imbalances. They may also indicate an underlying condition such as:

To reduce bloating or period-related weight gain, you may want to track your hormone levels throughout your cycle. A functional practitioner or nutritionist may be able to suggest effective ways to do this.

  • One common method is testing your sex hormones on day three and day 21 of your cycle. 
  • Another common method is the DUTCH test, a functional test that provides a deeper insight into several hormones, including estrogen and progesterone, as well as their metabolites. 

Once you’ve worked with your practitioner or nutritionist to identify specific hormonal imbalances, they can tailor a nutrition and lifestyle plan to help optimize your hormone levels.

Try Cycle Syncing 

Cycle syncing may be one way to support your body through the hormone shifts during your cycle. It involves aligning your diet, exercise, and other lifestyle habits with the phases of your menstrual cycle. This may look like:

  • Focusing on restorative and rejuvenating exercise during menstruation and the beginning of the follicular phase.
  • Eating more during the luteal phase, perhaps in preparation of your period. 

Listening to your body’s cues during the different phases may promote a healthy attitude towards menstruation, support your body during the hormone shifts and, in doing so, potentially help alleviate period-related weight gain.

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