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Why you feel so bloated on your period

reading time: 3 minutes reading time
pink balloon

Here we go again. It’s the week before my period and I just know what that means. My hands and feet inflate and my belly feels like a balloon. How I love the period bloat.

Bloating is one of the most common symptoms of premenstrual syndrome, affecting around 70% of women1. But what exactly causes bloating? Why do our bodies insist on giving their best balloon impersonation? And is there anything we can do to stop it?

Right, time for some science. Bloating happens because of an increase in the amount of water that leaves the blood stream and moves into the tissues. This water is important to keep your cells healthy. It delivers nutrients like sugar, salt and minerals and removes metabolic waste and debris left behind by dead cells. The amount of water that is retained in the body is tightly controlled by your hormones, and any imbalance can disrupt this finely tuned system2.

Your menstrual cycle is defined by fluctuating levels of several hormones, particularly oestrogen and progesterone. Oestrogen levels rise during the week before your period, which causes your body to retain more water. Progesterone usually has the opposite effect, but at this time of the cycle, the progesterone levels drop sharply. To accommodate the excess water, the abdomen expands, giving you that familiar ballooned and bloated belly.

The hormonal changes that occur during the menstrual cycle also slow bowel motility, increasing the amount of trapped gas, and cause the uterus to swell in anticipation of receiving an egg. Both of these add to the bloated feeling. Great, thanks hormones.

At this point, it may feel like the odds are stacked against you, but there are some things you can do to help. Here are some top tips to beat the bloat.

  1. Drink responsibly. Both caffeine and alcohol leave you dehydrated, which causes the body to hold on to more water. You don’t have to avoid them completely, especially if you’re like me and need caffeine to function as a (relatively) normal human. Moderation is the word of the day.
  2. Just a pinch of salt. The amount of water that enters the tissues is influenced by your levels of sodium and potassium. Simply put, too much sodium means more water is retained. Salt (sodium chloride) is the most common form of sodium in our diets, so try to use in moderation.
  3. ‘Ave another avocado. Foods that are high in potassium, like avocados, shift the sodium:potassium balance in the opposite way. Therefore, more potassium should lead to less bloating. Bananas, yogurt and sweet potatoes are also good options.
  4. Go pro-tein. I’m not saying that you should be inhaling protein shakes like that guy at the gym who flexes in front of the mirror, but getting more protein in your diet could help to relieve that bloated feeling. Protein in the blood absorbs water like a molecular sponge, so less enters the tissues. Lean meats, nuts and eggs are a good place to start.
  5. Run Forrest Run. A great way to feel less bloated is to maintain your exercise routine, even if you just want to crawl into bed and watch TV. Exercise helps to release trapped gas, increases your metabolism and aids digestion, all of which should help you feel less ballooned.


We all hate feeling bloated, but there are steps we can take to get some respite. Remember, these are just recommendations and may not work for everyone. It is important to find an approach that works for you and your lifestyle. One option is to consider a contraceptive that reduces the number of periods you have. To find out more about your contraceptive options read more here. If you find your bloating particularly uncomfortable, or it persists beyond your period, you may need to consult your doctor.


  1. http://www.womenshealthmag.com/health/de-bloat-during-period
  2. http://www.medicalnewstoday.com/articles/187978.php