Even when you’ve had a period for years, you can still get surprised by bleeding while wearing your favorite white dress, intense headaches while ovulating or cramping and overnight spotting after you thought your period was over.

Menstrual cycle tracking and syncing aim to better identify and take advantage of these reproductive phases. The booming practices—reaching around 50 million people worldwide—differ from the age-old myth that women’s periods naturally synchronize with each other in close proximity. Instead, women intentionally align their diet, fitness and sometimes even work schedules with their cycle. Hormonal patterns, though, aren’t clockwork: They vary widely among women and throughout our lives. 

“Normal is only normal for you,” emphasized Cedars-Sinai OB-GYN Kacey Hamilton, MD. 

On average, women rotate through around 400 cycles over the course of their lives: Understanding, listening to and nurturing your body’s rhythms can be an anchor. However, OB-GYNs strongly caution against a social media climate of reproductive health exaggerations and incorrect, potentially harmful advice.

“Knowledge is power,” Hamilton stressed, “but your menstrual cycle does not run your life.”

Women’s health experts encourage everyone who menstruates to monitor their cycle and establish a baseline. 

Generally, women move through a 28-day sequence (which can last up to 38 days): Your period launches a two-week follicular phase (when the ovarian cysts which house eggs mature); then, ovulation (egg release for fertilization) and “the most predictable,” luteal phase (fortifying your uterine lining and cervical mucus to keep a potential pregnancy safe).   

“Cycle syncing even at its core is an oversimplification and combination of what happens in both the uterus and ovaries,” Hamilton stressed. “It isn't medically how we think about these things.”

Still, logging your menstrual patterns can prepare you for commonly recurring challenges. For example, rapid hormone spikes in estrogen during ovulation, and progesterone in the luteal phase, often trigger headaches, more pronounced in women who struggle with migraines. Ovulation ruptures a cyst each month, releasing fluid that inflames and bloats your belly.

The movement is chipping away at taboos that keep women and girls embarrassed and in the dark about their own bodies. Whether you’re soaking through tampons hourly, or cramping so severely you can’t eat, menstrual and hormonal shifts shouldn’t interfere with your everyday life. Don’t try to treat these abnormal, disruptive symptoms at home, Hamilton urges: Visit a gynecologist, and if they don’t take you seriously, seek a second opinion. 

“Resting during your period won’t heal endometriosis, PCOS (polycystic ovary syndrome) or premenstrual dysphoric disorder (PMDD),” she said.

Read: Do I Have Premenstrual Dysphoric Disorder?

Menstruation underlies the vast majority of iron deficiency and related anemia, an overlooked public health crisis among women and girls. 

As you approach your period, iron is essential. Hamilton also encourages vitamin B and folate; leafy green vegetables such as spinach and kale are rich sources. Federal health officials recommend all women of reproductive age who aren’t pregnant consume 400 micrograms of folic acid per day.

In one study of menstrual cycle messaging on TikTok, researchers found more than half recommended adjusting meals based on whether you’re actively menstruating or in the follicular, ovulation or luteal phases. 

While eating for your cycle is wildly popular, such rigid, overly broad rules don’t consider differences between women, reproductive health experts say. In fact, beyond menstruation, there’s scant evidence supporting eating according to hormonal phases.

Throughout the month, Hamilton suggests whole foods such as fresh fruits, vegetables, grains and beans. Highly processed foods, as well as excess fat, can disrupt hormone regulation.

A balanced diet is good for everyone, she stressed. Your reproductive health is closely intertwined with your gastrointestinal, immune, vascular and every other system: “It all goes hand in hand.”

Even more cycle syncing content (57%) pushes similar exercise advice. Wellness coaches and social media influencers emphasize certain light or vigorous workouts during menstrual phases, claiming these adjustments can boost strength.

The problem with this advice? A sweeping volume of research contradicts any reproductive health impact on typical athletic performance—across exercise types, according to the Perspectives on Sexual and Reproductive Health study. 

Hamilton instead recommends consistent exercise, incorporating cardiovascular and weight-bearing activities (such as running or dancing) which are essential for reducing women’s higher susceptibility to heart disease and weakening bone density as we age. Regular physical activity also aids in hormone regulation, and among women who have endometriosis or chronic migraines, can even relieve painful hormonal flare-ups. 

For female athletes, there may be more room to consider reproductive cycle among a range of health factors—to protect joints and bones. Orthopedic research championed by Cedars-Sinai has uncovered a link between estrogen and progesterone surges and muscle and tendon flexibility, which could be to blame for women’s higher risk of joint injuries. Hamilton said the emerging connection may guide trainers to adapt exercise regimens during ovulation, compared to the follicular phase, or players to suppress the process with birth control.

Read: Hormonal Birth Control Might Reduce Female Athletes’ ACL Tears

Women’s health experts warn much of the conversation around reproductive cycles is restrictive and can spread damaging gender stereotypes that limit women to the womb.

Anyone outside the standard, such as those in perimenopause or on hormonal birth control, can’t rely on their body’s hormonal patterns. Supporters of cycle syncing tout naturally rebalancing hormones as its main supposed benefit, particularly when coming off years of birth control. But this approach isn’t rooted in science: OB-GYNs overwhelmingly agree that birth control doesn’t destabilize your hormone levels or impact long-term fertility. Your reproductive system should reset on its own if you discontinue medication.

Similarly, Hamilton reassures women that natural ebbs and flows don’t dictate how you feel about yourself or others. If you aren’t attracted to someone, you won’t suddenly notice them in luteal phase.

But wellness coaches and cycle syncers have tapped into a real use—sexual function. Women’s libidos often spike during ovulation, your fertile window. She encourages taking advantage of these boosts if you have a safe partner.

However, adapting your workload based on peaks in progesterone and estrogen won’t invigorate your focus or communication. Medical research hasn’t found any connection between regular hormonal shifts and cognitive function, speech, decision-making or efficiency.

“You are not less capable, less intelligent—less anything—because of natural fluctuations in your hormones—it’s a part of life,” she underscored.