Cramps. Mood swings. Unhealthy food cravings. Every single month, women across the world experience these symptoms and more as a result of premenstrual syndrome, more commonly known as PMS (or the worst thing in the world, depending on who you ask). Headlines claim a vast array of PMS solutions heralding everything from light exercise to a healthy diet as solutions for pain and cravings, but while women have been reporting PMS symptoms for centuries, not everyone even believes that they are real. But today the results are in: PMS is real, and doctors have started to understand why this monthly cycle can cause even the strangest of symptoms: junk food cravings.

What causes PMS symptoms?

PMS and its lingering symptoms are caused by neurotransmitters in the brain. When an egg is released from a woman’s ovaries, her hormones start to fluctuate to prepare her body for a possible pregnancy, and the hormones affect the brain’s chemical messengers. If no fertilization occurs, the uterus sheds its lining (which had thickened in preparation for potential pregnancy) and voila, period. It is during the first part of the period cycle, between the release of the egg and the beginning of the menstrual flow, that women experience PMS symptoms.

While doctors have documented the ways in which hormones affect neurotransmitters during PMS, the syndrome and its symptoms remain elusive. Most women report experiencing PMS symptoms, but there have been over 150 different specific symptoms reported ranging from irritability, anxiety, and cravings.

Does PMS cause junk food cravings?

Many women report pain and mental/emotional changes during PMS, but just as many people claim to crave junk food during this time of the month as well. Food cravings apart from PMS aren’t unusual: In one study, 97% of women reported having had food cravings that weren’t necessarily connected to their menstrual cycle. There is evidence, however, that women do eat more during the PMS phase of their periods than at other times of the month; sometimes they are eating up to 500 more calories per day. Additionally, instead of reaching for the carrots and celery, women experiencing PMS cravings tend to reach for something more delicious than carrots and celery: chocolate.

Why does PMS make you want to eat chocolate?

Although there may be significant evidence that PMS causes food cravings, it’s unclear exactly why. One theory is that women crave carbohydrates during PMS to make their brains happy: Carbs increase the levels of serotonin in the brain, which is a well-known neurotransmitter that increases an individual’s feeling of well-being. In some studies, women who were given increased levels of serotonin separate from food during PMS did indeed report fewer cravings, showing that perhaps this neurotransmitter is the motivation for the chocolate eating.

It is also possible that the answer is more straightforward: Chocolate is tasty. Good food can make you feel better, and if you’re in the middle of PMS-induced anxiety or pain, a chocolatey snack can be an easy and affordable way to make yourself happier.

What can you do to avoid PMS symptoms?

PMS is a tricky syndrome to treat because every woman is different. The first step in getting rid of your PMS symptoms, whether they’re cravings or anxiety, is acknowledging them. Track your feelings (mental and physical) throughout your cycle so you’re more aware of why you’re feeling the way you’re feeling. PMS-related advice is everywhere, so after you’ve identified the way PMS affects you, try some solutions while knowing that they might not all work for you. Practice meditation, yoga, or exercise throughout your cycle, or focus your diet on calcium-rich foods and whole wheat products. And don’t feel bad about the occasional PMS-fueled chocolate binge.