Meredith Vogel lost her period when she was 22.

As a college student, she worked out for about half an hour on an elliptical machine four or five times a week. She started watching what she ate too.

While she never skipped a meal, Vogel did cut back on her portions and dinners out with her boyfriend. She lost some weight, and within six months her period disappeared.

On one hand, Vogel was relieved not to get her period. “Part of me didn’t care,” she recalled.

Her doctor couldn’t figure out what was wrong. According to body mass index (BMI) guidelines, she was a healthy weight for her 5-foot-4 frame.

But her blood work showed elevated liver enzymes, blood sugar, and cholesterol levels, indicating that something was amiss in her body.

Finally, doctors told her she needed to eat more.

It turns out Vogel, who’s now 39 and lives in Long Island, New York, wasn’t adequately fueling her body. Her body reacted by going into starvation mode, slowing down her metabolism and conserving energy.

“At that time, there wasn’t much information [about losing your period]. I didn’t think I was doing anything wrong,” said Vogel. When she gained weight, her period reappeared.

Amenorrhea, or the absence of menstruation, isn’t a new phenomenon.

However, it’s often associated with professional athletes and assumed to be a sign that the body is extremely fit, a consequence of adapting to high levels of exercise. Or it’s considered a side effect of an eating disorder.

Yet everyday women are just as susceptible to losing their period.

Signs of menstrual dysfunction occur in as many as 60 percent of recreational athletes, said Nancy Williams, professor of kinesiology and physiology at Penn State University.

In a survey of over 300 women with amenorrhea, Nicola Rinaldi, author of “No Period. Now What?” found a wide range of exercise frequency and intensity among women who’ve lost their periods, including women who exercise three to four days a week for less than an hour and women who don’t exercise at all.

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“My experience has been that it’s not your exercise but how you’re eating to fuel [your exercise],” that causes health concerns and the loss of a period, Vogel shared. (Photo via Vogel)

How exercise can cause irregular periods

Exercise itself doesn’t cause menstruation to stop. It’s the mismatch between energy consumed and energy used, resulting in what’s called low energy availability.

“It doesn’t necessarily depend on expending a high amount of calories,” Williams pointed out. “But when someone’s exercise expenditure causes them to tap into the energy they need to run their body’s day-to-day processes, it can cause a problem.”

When your body doesn’t have enough energy to keep your systems humming, it shunts energy away from nonessential ones like reproduction and growth, including building bone.

As a result, the hypothalamus, a region in the brain, slows or stops the release of the hormones that control ovulation.

Researchers at Penn State University found that reducing calories by 470 to 810 a day compared to baseline needs over as few as three menstrual cycles is enough to disturb a woman’s cycle.

Some changes were overt, like disappearing periods, while others were subclinical and not noticeable.

Low energy availability can occur for many reasons — dietary changes or restriction, exercise, stress, or a combination of these factors, explained Catherine Gordon, MD, director of the Division of Adolescent and Transition Medicine at Cincinnati Children’s Hospital Medical Center and lead author of new guidelines on treating amenorrhea from The Endocrine Society.

Unfortunately, there’s no gold standard test, and each person has their own internal set point. A level of diet and exercise that might set one person off may be OK for someone else.

For example, Terena Bell experienced changes to her period in her early 30s.

She went from doing no exercise to 90 minutes of yoga a day. As a result, her periods became very light, and her cycles lasted a day to a day and a half. “I didn’t think of yoga as exercise and as something that would mess up my period,” she said.

Ottawa-based Jesse Blondin, 35, trained similarly to other recreational triathletes and runners she knew — 45 to 60 minutes a day, maybe a little longer on the weekends.

However, when she stopped taking birth control pills to try to start a family, she didn’t get a period.

“I had no idea I didn’t have a natural cycle,” she said. “It was frustrating because I associated [amenorrhea] with super lean people like gymnasts and Olympians.”

Yet her blood work revealed that her hormone levels were near zero.

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“I’m young. I’m healthy. I’m active. I should have no problem getting pregnant. But it turned out that the thing I was doing to be healthy was causing problems,” Jesse Blondin said. (Photo via Blondin)

Your period is a vital sign — especially of bone health

While most women would rather not deal with the hassle of their periods, Gordon considers the menstrual cycle a vital sign.

Like your heart rate or pulse, your period can offer a glimpse into what’s happening inside your body and a sign that your body’s systems are running smoothly.

Your period can also point to longer-term health problems.

“If your periods are spacing out, your cycles are getting longer, or your flow is getting light or stopping, it can be a sign of estrogen deficiency,” said Gordon, which can affect your fertility.

Amenorrhea is also a hallmark sign of the female athlete triad, which involves three interrelated conditions that frequently coexist — energy availability, menstrual function, and bone mineral density. This condition has been linked with cardiovascular health, resulting in endothelial dysfunction and higher cholesterol levels.

The connection between amenorrhea and bone health is most concerning to doctors. “If you start losing your menstrual period, you may be on your way to losing bone,” said Williams.

Women (and men) reach their peak bone mass or highest bone density between the ages of 20 and 30.

From that point on, you maintain what you have and begin to lose bone as part of the aging process.

If you don’t experience the natural monthly surge of bone-building and bone-protecting estrogen, especially during the critical bone-building years of adolescence and early adulthood, you may not achieve your maximum bone mass.

As a result, you may have weaker bone tissue and be at greater risk for bone stress injuries like stress fractures, especially in your back, pelvis, and heel bone, according to a 2017 study from The American Journal of Sports Medicine.

You’re also susceptible to early diagnosis of osteopenia and osteoporosis.

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“No Period. Now What?” and the Facebook group by the same name help women make changes to their health, discuss body image issues amplified by weight gain, and support each other, as they usually have to give up the exercise they love for a while.

How to tell that you may be experiencing amenorrhea

Whether you use an app or a good old calendar, keep an eye on your cycle. Take note of how often you get your period, how long it is, and your flow.

“Your full cycle should be normal length, between 26 and 36 days. You should have a decent amount of bleeding for two to three days at the beginning of the cycle,” Williams shared.

If you notice less bleeding or fewer days of bleeding, or if you have nine or fewer periods a year, see your doctor.

Other signs to look out for include a history of stress fractures or other bone stress injuries.

You may also feel cold or have a lower resting heart rate due to reduced metabolism.

“You start to see the body compensate when metabolism slows down or a person might conserve energy from a movement standpoint, exercise really hard, but not do much the rest of the day,” Gordon said.

Your doctor will likely conduct a physical exam and lab tests to rule out other possible causes for amenorrhea such as pregnancy, polycyclic ovarian syndrome, or hypothyroidism.

However, Gordon advises against taking oral contraceptives to induce bleeding and to increase bone density. “It’s not effective for bone health,” she said.

Recovery is possible

Recovery will likely require changes in behavior to allow your body to heal, such as decreased exercise, increased and improved dietary intake, and reduced stress.

The Endocrine Society’s guidelines recommend working with your doctor, an endocrinologist, a registered dietitian (who can evaluate your caloric needs and create a road map toward a balanced level of energy), and a mental health profession (who can help treat any underlying disordered eating or stress and help with behavior change).

“What you need to do to recover doesn’t mean how your life has to look forever,” said Rinaldi.

You can eventually resume exercising, and even training for marathons and triathlons.

According to Rinaldi, it takes six months on average for a woman’s period to return.

As far as researchers know, amenorrhea doesn’t cause irreversible damage to fertility, said Williams. Rather, it causes transient infertility, meaning it’s very possible to get pregnant after your cycle resumes.

For women experiencing amenorrhea, it can feel lonely.

“Among active friends, no one talked about not having your cycle,” and it was hard to find information online, Blondin shared.

She stumbled onto Rinaldi’s No Period. Now What? Facebook group, a supportive community of approximately 2,000 women who’ve experience trouble with their menstrual cycle.

“It’s really key for women in recovery to be able to talk to others going through the same thing,” said Rinaldi, who experienced amenorrhea herself.

“It can be hard to buck the trend to eat more and exercise less, especially if you’re involved in the running community or CrossFit,” she said.

Remember, food is fuel, especially when you exercise.

“As you start to exercise, you have to up your calories slightly to compensate for that,” Gordon said. “You need to give sustenance back to the body, and it’s important for reproductive and bone health.”