This article is brought to you by Precision Nutrition

Fit women often lose their menstrual period when training hard or dieting to lose fat. While some think it’s no problem, this couldn’t be further from the truth.
In today’s article we explore why losing your period can be a negative thing. We also share some tips on staying lean and fit while maintaining your hormonal health.
[Note: we’ve also prepared an audio recording of this article for you to listen to. So, if you’d rather listen to the piece, click here.]
Maryann is young, active, and (apparently) healthy.
She eats a self-described “clean” diet. She weight trains twice a week, and does about two hours of cardio four or five days a week.
A year ago, at age 27, she stopped getting her periods.
She didn’t mention it to her trainer. And it never occurred to her to consult a doctor.
In fact, secretly, she felt relieved. After all, she didn’t want to get pregnant.
Besides, dealing with her monthly cycle had become a hassle. It interfered with her exercise program. And the weight fluctuations played with her mind.
So…no period, no problem. Right?
Understanding the menstrual cycle
The menstrual cycle is a series of changes women’s bodies go through when preparing for the possibility of getting pregnant.
Here’s how it works…
Every month, one of the ovaries releases an egg. (This process is called ovulation.)
At the same time, body-wide, hormonal changes prepare the uterus for pregnancy.
To begin with, a hormone called gonadotropin releasing hormone (GRH) is sent from the hypothalamus to the pituitary gland.
This cellular cross-talk then triggers the pituitary to release two other hormones: follicle stimulating hormone (FSH) and luteinizing hormone (LH).
These hormones then travel to the ovaries and tell them to make estrogen and progesterone.
Of course, the amount produced depends on the which phase of the menstrual cycle one is in (i.e. follicular vs. luteal).
If ovulation takes place and the egg is not fertilized, the lining of the uterus sheds through the vagina. And this is what most people think of as a “period”.
Energy balance and menstruation
Back to Maryann…what went wrong with this normal process?
(And why does this happen to so many female exercisers?)
In simple terms, a woman’s body is extremely sensitive to energy fluctuations.
When a woman is eating a restricted diet (especially if she’s fasting or skipping meals), or she’s exercising strenuously for hours every day, her body recognizes this negative energy balance as a threat to her survival.
So it shuts down “non-essential” body processes such as reproduction. In short, she becomes infertile. The scientific term for this is hypothalamic amenorrhea.
The role of leptin
Girls now get their first period (aka menarche) earlier than in our grandparents’ generation.
This may be because, on average, kids are heavier than in the past.
But to understand that, you need to recognize the relationship between the hormone leptin and the hypothalamus.
Body fat produces leptin. So, when a child gains enough weight, there is a threshold amount of leptin produced to signal the hypothalamus to kick off the first menstrual cycle.
Since kids are becoming heavier sooner than they used to, their periods are also starting sooner.
The opposite is true for women who get too lean or who restrict calories too much.
Getting too lean decreases the amount of leptin circulating in the body. This, in turn, decreases the activity of the hypothalamus.
Since Maryann was restricting calories, exercising almost every day, and losing body fat, this combination of factors could have triggered the loss of her period.
The role of stress
As discussed, women’s physiological sensors are highly tuned in to sensing deficits. Whether in energy balance, essential nutrients, or body fat, women’s bodies quickly respond to deficiencies.
The “deficit setpoint” will vary from woman to woman.
Some women can be naturally leaner, can work out with higher volume and intensity, or can eat fewer calories while staying hormonally healthy.
Other women’s systems are more sensitive to any perceived restriction.
Of course, stress — of any kind — will make things worse.
For many female athletes (or even just active women), the demands of training and competing, pressure to succeed, and other normal life stressors such as jobs, school, finances, relationships, etc. can combine with nutritional and physiological stressors to shut the system down.
The same thing can happen when the sympathetic nervous system (SNS), aka our “fight-flight” system, is overtaxed. For instance:
  • if we rely too much on stimulants such as caffeine
  • if we don’t calm down and recover often or deeply enough, giving our parasympathetic nervous system (PNS), aka our “rest and digest” system, time to activate
  • if we’re constantly in self-critical, “gotta do it all myself”, control-freak or perfectionist mode
  • if we don’t get enough quality sleep
  • if we skip meals or fast too restrictively or too often (which amps up our stress hormone production)
  • if we beat the heck out of ourselves with too many, too-demanding high-intensity workouts (such as Crossfit, MMA conditioning, or sprint intervals)…
…then our stress hormones are always on “high alert”, telling our bodies that threats lurk around every corner, and it’s not safe to reproduce.
Since many female athletes or recreational exercisers can also be driven, high-achieving people who seek out stress and challenge, and push themselves to be ever-better…well, it’s sometimes the perfect storm.
Why is hormonal health important?
Unless you’re planning on starting a family, infertility and losing your period might seem like no big deal. In fact, it might seem a nice break from the hassle of having periods.
Not so fast.
Remember that your period isn’t just about pregnancy. Rather, it’s a side effect of normal hormonal health.
In other words, losing your period (or having significant irregular periods) means that something is “off” hormonally.
Think of your period as a dashboard indicator light. When you lose it, the light starts blinking: Hormonal health alert! And you ought to pay attention.
In the case of hypothalamic amenorrhea, those messages we talked about earlier — from the hypothalamus to the pituitary to the ovaries — significantly diminish. And that means the production of hormones like estrogen and progesterone is dangerously reduced.
Why is that a problem? Your body needs these hormones for bone strength.
(They’re also required to keep you feeling healthy, energetic, and even-keeled psychologically.)
In fact, because of the link between estrogen, progesterone, and bone health, many fit young women who lose their periods end up with weaker bones than their eighty year old grandmothers.
And yes, that includes the ones like Maryann, who regularly perform weight-bearing exercise, and whose diets are rich in calcium and vitamins D and K.
Neither strength exercise or proper nutrition is enough to make up for hypothalamic amenorrhea.
The brain bone’s connected to the… thigh bone
Unfortunately, a lot of young female athletes aren’t aware of their body’s needs for estrogen, so when they lose their periods as part of their training, they simply take it for granted.
In fact, the first issue that often drives women like Maryann to the doctor is not the loss of menstruation. It’s a mysterious pain in one of their thighs.
The cause of that pain — as their doctors can easily discover with a little investigation — is a stress fracture.
This happens so often that there’s even a name for the syndrome: the Female Athlete Triad. (Shortens to FAT. Which is ironic, because most of these patients are anything but.)
Core symptoms of the Female Athlete Triad are:
  • amenorrhea (being without a period for three months)
  • decreased bone mineral density
  • low energy availability (including disordered eating)
But the fun doesn’t stop there.
Estrogen and progesterone — along with other sex steroid hormones such as testosterone — have wide-ranging effects throughout our bodies.
So if your hormones are disrupted, you might also experience:
  • fatigue and low energy
  • disrupted sleep (e.g. trouble falling or staying asleep, including the dreaded 3 AM “blast out of bed”)
  • hair loss (or for some women, facial hair growth)
  • cold hands and feet
  • skin problems like dry skin or acne flareups
  • weight changes and changes to where you put on body fat (e.g. more accumulating around your middle)
  • slow injury healing; more inflammation
  • anxiety / OCD, low self-esteem and/or depression
  • elevated carotene in the blood
  • anemia
  • orthostatic hypotension
  • electrolyte irregularities
  • vaginal dryness or thinning of tissues
  • bradycardia (slower than normal heart rate)
  • chronic pain (even if it’s just a general achiness or soreness)
  • changes in digestion (such as constipation or bloating)
  • changes to your breast size or shape (which you’d probably notice as bras not quite fitting right all of a sudden)
I can’t tell you how many times a young female athlete has come into my clinic complaining of thigh pain and, surprise, no periods. Further exploration usually reveals a pattern of restrictive eating or excessive exercise. Not to mention many of these other symptoms.
It’s a real shame. Because along with their periods, these young women are losing the very thing that matters to them most: Their health.
But wait…men are at risk too
Although the syndrome may be called the “female athletic triad,” males are not immune to a similar phenomenon.
Remember the story of my client, Jason? A low calorie diet combined with high stress spelled serious exhaustion for this otherwise healthy personal trainer.
Just like in women, when a man’s energy availability is chronically low, his hormonal health is at risk.
In Jason’s case, this showed up as a thyroid problem. We often see testosterone plummeting too. The same hypothalamus – pituitary – ovary/testis link is the culprit. It’s the same disruption pattern.
So if you’re a guy, please don’t think this article is irrelevant for you.
In fact, you should be especially cautious. After all, you don’t have that obvious signal — a missed period — to warn you that you’re at risk.
Which is why we all need to keep energy in balance or health will suffer.
Energy deficit…or nutrient deficiency?
While energy deficits are probably the most common cause amenorrhea in female athletes — and low thyroid hormone/testosterone production in men — they’re not the only cause.
Vitamins and minerals
Precision Nutrition’s Dr. John Berardi has worked with several fitness / figure competitors who lost their menstrual period while preparing for a contest.
After introducing a few vitamin and mineral supplements, their periods returned.
Of course, negative energy balance and nutrient deficiency are intimately connected. If you’re not getting enough food overall, you’re probably also missing out on specific micronutrients.
What surprised Dr. Berardi was the way these athletes responded to vitamin and mineral supplementation alone (without additional calories).
“I was amazed when we experimented with this. We tested removing and reintroducing the multvitamin/multimineral a few times. When the vitamins and minerals were in, periods returned. When they were out, menstruation stopped.”
This suggested to him that maybe, at least some of the time, energy deficit isn’t the problem so much as is nutritional deficiency.
In the Precision Nutrition Coaching program, the PN Team has also noticed that adding a handful of slow-digesting carbohydrates to most meals also helps, as does making sure to get enough carbohydrates post workout.
Many health-conscious women restrict carbohydrates, particularly starchy or sweet carbs (such as potatoes or bananas), believing that carbohydrates are “bad” or that low-carbohydrate diets are “good” for everyone.
The result is the same: hormonal disruption, amenorrhea, and a physiological stress response to what the body thinks is deprivation.
There may be a good reason for carb cravings in the luteal (aka premenstrual) phase of the menstrual cycle: Carbohydrates may serve a physiological need in women that we don’t fully understand yet.
With that said, the idea of specific micronutrient deficiencies — or even a link between carbohydrate intake and amenorrhea — is only a hypothesis. But it’s definitely food for thought.
Other causes of amenorrhea
Don’t ignore a series of missed periods. Along with nutritional deficiencies and energy imbalance, you could be dealing with quite a few serious underlying issues.
These include:
  • polycystic ovary disease (PCOS)
  • thyroid problems
  • uterine scarring
  • pituitary tumours
  • premature menopause
Not to scare you or anything, but this is why it’s so important to see your doctor if you stop getting your periods. Even if you don’t want to get pregnant.
Fixing what’s wrong
So what happened with Maryann?
She cut down on a bit on her cardio training. (She didn’t eliminate it entirely, of course). She also started eating 500-1000 additional calories each day.
Within a few months, she did gain a few pounds. However, because we replaced some of her cardio with weights, most of that gain was lean.
Either way, not only did we improve her strength and lean mass, without causing fat gain, we also improved her hormonal health, reducing her risk for other health problems.
What you can do
If you’re a health conscious woman who works out and eats well take note: Losing your period isn’t something to take lightly.
If your menstrual cycle becomes irregular or stops altogether:
  • Make sure you’re meeting your body’s energy needs.
  • Increase calories or reduce exercise by a little bit.
  • Ensure you’re getting enough rest.
  • Consider taking a high quality vitamin/mineral supplement.
  • Consider adjusting your carbohydrate intake to consume a handful of slow-digesting carbs at most meals. (And depending on your athletic needs, maybe even more.)
  • Check your head. Mindset matters. Hormones respond to thoughts and feelings along with nutrients or activity.
And see your doctor to rule out underlying problems.
It’s never too late to start making healthier choices. Because, while you may not want to start a family today, you’ll want to be walking on those bones. For life.


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