Period Weight Gain Explained

Monthly temporary weight gain, we all have experienced this, but for some reason when we step on that scale we aren’t entirely convinced that it’s our period causing the weight gain. Then we blame ourselves for going over our calorie target that ONE day, or having an extra glass of wine that ONE day. I have to say, don't stress the small stuff! Those extra calories here and there will not be why you are seeing monthly weight gain on the scale.

According to it's normal to gain about 1.3-2.2kg during your period. So I’m here to explain to you what exactly is happening during that time of the month that causes temporary scale weight. 

Hormonal Changes

Just before your period starts the sex hormone estrogen peaks. Why does this matter? Well, the hormone estrogen causes salt and water to be retained in the body’s tissues. This water retention is usually the culprit for the swelling in your breasts, stomach, or even legs. Which means the weight gain you see during this time is an increase in water weight, not adipose tissue (the fancy name for body fat). When estrogen levels drop as you start your period, you’ll see a reduction in water retention... for now… although it's usually the time the cramps kick in... oh joy!

The other hormone that affects scale weight during your period is progesterone. Progesterone levels spike in the second half of your cycle, this then leads to water retention (which leads to water weight on the scale) and other symptoms such as breast tenderness. Ever feel like your bras are too small during this time of your period? Well, you can thank progesterone for that! But not to fear, it’s only temporary much like the pre period water weight.

A side note, to make you feel better, water retention is a common PMS symptom. According to Tacani, PM et al. (2015) it affects 92 percent of women who menstruate!

Read More: Tips To Make Weight Loss Easier


Just to add salt to the wound, no pun intended, if you experience PMS during that time of the month gastrointestinal (GI) upset may also occur. Hormonal changes during your period can increase gas in your gastrointestinal (GI) tract and cause bloating. In some women, these fluctuating hormones during your period can also lead to constipation and/or diarrhea! Which can also alter the scale weight.

Bloating may be different for everyone, but usually starts five days before your period and continues into the first few days.

Period Cravings

PMS also leads to changes in appetite. Hellooo chocolate! So lets be honest here, sometimes we do give in to temptation which can affect our weight loss goals. According to studies have shown that we tend to crave foods high in fat and carbohydrates during specific phases of the menstrual cycle, and we also tend to take in more calories during these specific phases. And if we go for more salty foods this can cause MORE water retention than just hormonal retention. 

It’s advantageous to watch your salt intake during this time and drink lots of water! Albeit temporary weight gain, if you DO end up going over your calories every day for a week you might actually see fat gain. It takes approximately 7,700 calories over your maintenece caloires to gain 1kg, which works out to be over 1000 excess calories a day over 7 days. So actual weight gain is harder than you would think, but if you over eat by 500 calories a day for 7 days thats half a kilo. Food for thought! ... I'm killing it with the puns today. 

Read More: Is Wearing a Waist Trainer the Secret to Reducing Belly Fat?

Some takeaways and tips

  • The weight you see on the scale during your menstural cycle is usually hormonal/GI backlog
  • Drink lots of water
  • Keep up the exercise (this also helps for reducing water retention)
  • Eating healthy foods e.g fruits, vegetables, whole grains and lean meats
  • Take magnesium to help with electrolyte levels (helps with PMS & according to lower-than-normal levels can also cause constipation (and thereby, bloating), fluid retention, and gas during your period. 
  • Try to avoid having too much caffeine as it can increase bloating


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