Noticing you gain weight before your period? You’re not alone in that. But before you sweat those extra few pounds, let’s talk about why it’s happening.
Feel like you gain with Aunt Flo? Here’s what common
If it’s almost time for your period, you may have wondered if it’s the reason behind weight gain. Maybe things aren’t fitting right. Or, you feel like you look a little bloated. Either way, it’s tempting to hop right on the scale and see just how much your weight’s inched up. But if that’s what you decide to do, take the number with a grain of salt—because it’s not permanent.
So how much weight is normal to “gain” during your period, anyway? It’s super common for women to notice an increase anywhere from 1 to 6 pounds. But everyone’s different. While you may look at your skinny jeans and think “no way,” your friend might not be bloated at all.
OK, so why do I gain weight before my period?
Period weight gain usually comes to two things: hormone fluctuations and the eating habits you have around your period.
Estrogen levels + your weight
To get an idea of what’s going on in your body, let’s look at the sex hormone estrogen during your cycle. After reaching high levels, it ultimately drops right before your period. Even though we think of estrogen as a reproductive hormone, it actually affects a lot of different things in your body. For example, estrogen can influence how much water you retain. (Hello, water weight!)
Serotonin + cravings for sugary foods
When estrogen decreases, a hormone called serotonin decreases right along with it. That decline of serotonin is actually a pretty big deal for your mood and your weight. Having less serotonin puts your appetite in overdrive. Instead of checking in with your body on what you need or what sounds good, you’re way more apt to reach for sugary treats when serotonin’s low. That’s because, in an effort to raise serotonin, your body will crave foods that are high in refined carbohydrates. The reason? Your body is super smart. Instinctively, it knows that these sugary foods help get your serotonin levels back up fast.
How those sugary foods cause a fast (but temporary!) weight gain
Chocolate. Cake. Ice cream. All those sound amazing when your estrogen and serotonin drop. But rest assured: almost none of us are eating enough in the days before our period to gain several pounds of fat. Here’s what’s really happening. Estrogen’s affecting how much water you retain—and your lower levels of serotonin are making you want to eat all the things. But even though you’re not eating enough to truly gain a few pounds, all of the sugar in those treats can make a sudden impact on the scale.
Eating foods loaded with sugar causes your insulin levels to go up. This makes your kidneys hang onto extra sodium and water—which will make you feel puffy fast. Plus, when you eat a lot of sugar, some of it gets stored as a form of glucose in your liver and muscle cells. For each gram of glycogen (a form of glucose) your body tucks away for future fuel, it does so with 3 to 4 grams of water. Depending on the amount of glycogen your body has stored, you could easily be looking at 5 extra pounds of water.
Is period weight permanent?
Weight gained right before your period typically falls off shortly after. The reason? Your estrogen and serotonin levels are back on the rise, and your appetite backs off—and so do all the sugar cravings. Consuming less sugar means your insulin stays stable. No longer do your kidneys need to hang onto extra water. Plus, fewer carb-y treats means your body will burn through its glycogen stores. Which is great news. Because as it does, all the water weight that’s stored with it will be shed too. The result: your jeans fit, and the scale’s right back to where it was. Until next month, anyway.