And according to Amy Shah, M.D., there’s a perfectly good reason we might feel a little under the weather around that time of the month, and it has everything to do with our hormones. Although you might think cutting back on IF during your period is the way to go, this doc believes fasting while you’re menstruating is actually just fine—it’s only the week before that’s a no-go. Here’s why you shouldn’t fast right before your period starts and how to do it safely to reap the most benefits. Your estrogen experiences a steep drop at this time, which leads to cortisol sensitivity (our stress hormone). That’s why right before your period, you might experience changes in your mood and energy levels, or you might have some killer sugar cravings, which Shah says we can chalk up to this estrogen drop. Because your body is more sensitive to stress, she recommends that you steer clear of any additional stressors in your life, including high-intensity workouts and—you guessed it—intermittent fasting. Sometimes these hormetic stressors are a great thing, as they can teach your body to grow and become resilient, but Shah believes we should take it easy when our bodies are more stress-sensitive. “That week before your period when you feel naturally kind of down, give your body a little rest. Maybe go for a massage, spend some time in nature. Have some really good self-care time during that week,” she tells me. That said, she recommends reducing your fast if you can’t take a break from it entirely. This means fasting only 12 hours instead of your regular 18, if you’re an IF pro. The key is taking it down just a little bit, just so your body isn’t experiencing too much stress. “Whatever you’re used to, just turn it down a notch,” she recommends. Shah also typically takes magnesium supplements during this week to help ease any PMS symptoms. If you’re especially magnesium deficient (and, according to research, about 50% of Americans1 are), you can make sure to add some magnesium-rich nuts and seeds to your diet as well. You might not experience those big, recognizable changes in your mood and energy levels during your menstrual cycle, but you should still be mindful of Shah’s tips to cut back on fasting, especially if you’re feeling a little more stressed and tired than usual. “This method of intermittent fasting still works; it’s just not as extreme,” she adds. However, Shah recommends you shouldn’t jump right into it as soon as your period starts—rather, starting around day two or three of your period is best. During the first couple of days where your flow is heaviest, it’s common to still feel tired, as you’re just recovering from your hormonal crash and you’re losing a fair amount of blood. Once your hormone levels start to rise, you’re going to feel noticeably more energetic—that’s when you can kick up the fasting and HIIT workouts, Shah says. For some reason, there’s this pervasive notion that we should amp up the self-care on our period. While it might still feel good, it’s really the week before when our bodies could use the self-love. “I think the rumor comes from the fact that people equate the period as all the same,” Shah tells me. When in reality, you might feel sluggish the first couple of days on your period (your body is still experiencing that hormonal crash from the week before), but during the latter half of your cycle, your body is stress-resilient and your hormones are at pretty adequate levels—great levels, even. “If your hormones are balanced, you eat well, you sleep well, and you take care of your stress, by day two or three you should be feeling pretty good,” Shah adds. The key take-away? Always listen to your body as best as you can. If you feel great, then great! Fast away. But if you’re experiencing some of these symptoms Shah mentions, checking in with your hormones may do you some good—and a break from fasting may even help you yield better results.
