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Female Hormones: What Happens During Your Period?

One thing is becoming increasingly clear to me: women don’t have a good enough understanding of their own physiology. It’s bad enough that we aren’t familiar with our own anatomy (hence, my intention to educate everyone about their pelvic floor). But, how many of us have had our period for more than 15 years and still don’t really know what’s going on? I’m guessing the vast majority of us.

The thing is, endocrinology is complex. One hormone always affects multiple other hormone systems, so I’m not attempting to give you an in-depth understanding of the endocrine system. But, I am going to spend the entire month of October talking about female hormones and opening a discussion to facilitate understanding this system when it comes to our reproductive organs. After all, women deal with their cycle pretty darn regularly, so we should probably understand it a bit better. Keep in mind, I am a physical therapist and nutrition therapy practitioner, so I am NOT a medical doctor and am not giving medical advice. If you have anything abnormal going on with your cycle, please consult with your OB/GYN!

Alright, let’s start with the basics. Women have two major sex hormones: estrogen and progesterone. We also have a little bit of testosterone (yes, women have testosterone, although these levels should be low). Here are their functions:

  • Estrogen: It’s made in the ovaries, as well as the adrenal glands and fat cells. Estrogen plays a big role in sexual development and puberty (think: breast development, pubic hair, menstruation). Estrogen also has roles in bone growth and health, as well as fat deposition (estrogen increases the function of lipoprotein lipase, which converts fatty acids in the blood into stored fat). There are 3 types of estrogen, which will be discussed in greater detail in a later blog post when I talk about birth control.  They are:
    • Estrone (E1) is a form of estrogen that is present even after menopause; it is made by both the ovaries and the adrenal glands. It’s also made by fat tissue, so present in higher quantities in obese women. It has been linked to breast cancer and endometrial cancer. It is the least potent of the estrogens.
    • Estradiol (E2) is the strongest of the estrogens and is made in the ovaries. Its production will decrease with age. It works to mature and stimulate release of an egg from the ovary.
    • Estriol (E3) is the primary estrogen present during pregnancy. It is often undetectable in women who are not pregnant.
  • Progesterone: It’s made by the corpus luteum (a temporary gland made after ovulation during the second half of the menstrual cycle) it is also produced by the placenta during pregnancy. Progesterone works to promote pregnancy by thickening the endometrial lining of the uterus. It also inhibits your uterus from contracting, which will promote fertilization and pregnancy. As long as progesterone is high, your body will not ovulate. This is the hormone that helps maintain a pregnancy!
  • Testosterone: This hormone has a role in bone formation, protein synthesis (think: muscle synthesis) and red blood cell production.

Of course, hormones levels can become unbalanced for a variety of reasons (a topic too complex to discuss in this post, but you can bet I will talk about it in coming posts). Here are some signs and symptoms of hormone disruption:

  • Low estrogen: Decreased frequency or cessation of periods, hot flashes, thinning and dryness of vaginal tissue, dry skin, decreased libido and mood swings. This can also cause headaches (recall that the drop in estrogen before the period can trigger migraines in some women).
  • High estrogen: Weight gain in hips/thighs, increased PMS, fibrocystic breasts, uterine fibroids, fatigue, decreased libido, and mood changes (especially depression)
  • Low progesterone: Uterine bleeding, irregular periods, missed periods and frequent miscarriages


Alright, so let’s look at the timeline:

  • Days 1-14: Follicular Phase
    • Day 1 is your first day of heavy bleeding. During this time progesterone and estrogen are low and you shed your uterine lining.
    • After your menses, a few follicles are acted on by follicle-stimulating hormone (FSH), which is released by the pituitary gland. (Side note: a follicle is a sac containing one egg; they take up to 100 days to mature prior to the follicular phase). FSH pushes your follicles to start making estradiol, which leads to a surge in your libido and it also stimulates your uterine lining to thicken (in preparation for fertilization). So, it stands to reason that the mores estradiol you have, the thicker your uterine lining will be, and the more you will bleed.
  • Day ~12-14: Ovulation
    • Eventually one or two of your follicles will swell enough to be released from the ovary. The pituitary gland releases luteinizing hormone (LH), which stimulates ovulation along with an estrogen surge. This event takes minutes to hours, but it is brief. Estrogen levels will then dip briefly.
  • Day 14-28:  Luteal Phase
    • Once your follicle has been released, it transforms into the corpus luteum, which is temporary gland that secretes progesterone. It can grow as large as 4cm in a matter of one day! The goal of the corpus luteum is to maintain a pregnancy by producing high progesterone levels. It will last up to 3 months if you do become pregnant (until the placenta takes over with progesterone production).  During this time, progesterone levels rise at a rate greater than estrogen and they find a peak ~5 days before menstruation. When an egg is not fertilized, progesterone levels fall and the uterine lining is shed. Release of prostaglandins help the uterus contract to shed the lining.

What does a “normal” period look like?

  • NOTE: A “normal” period by definition implies that menstruation happens following ovulation (which does NOT happen when you’re taking the pill). So, if you are taking birth control, this information may be different for you!
  •  A normal period should be regular (no sooner than every 21 days and no longer than every 35 days).
  • During a normal you should not bleed excessively (less than 80mL of blood or less than 16 tampons filled over the entire course of your menses).  
  • Normal periods should NOT cause debilitating pain.
  • Spotting associated with ovulation can be normal, as can spotting two days prior to start of menses.
  • Minor pain associated with ovulation is also normal.

Ok, so what about PMS? Premenstrual Syndrome symptoms, by definition, must occur 10 days prior to your period and resolve within 2 days after starting your period. Minor PMS symptoms are normal, but can be controlled and even eliminated in some cases.

What are the common symptoms and causes of PMS?

  • Mood changes and fatigue– Estrogen is known to affect the mood, and both estrogen and progesterone are known to affect that hypothalamus, which can cause fatigue.
  • Headache – The dramatic reduction in estrogen right before menses can trigger migraine headaches.
  • GI issues – As I said before, prostaglandin release causes the uterus to contract. And it doesn’t target just the uterus. This means, that your entire GI tract may be stimulated to contract more, which can cause diarrhea and nausea.
  • Bloating – Progesterone can have a huge effect on fluid retention, which causes bloating. Estrogen can also cause bloating by increasing the action of vasopressin, which essentially makes your body retain water.
  • Cravings – These can be attributed to a decrease in estrogen – your body starts saving glycogen in preparation for pregnancy and your body craves those carbs. Some research has also shown that you burn about 100-200 extra calories in your premenstrual period.
  • Other symptoms include breast pain, acne, fatigue and cravings and are due to an increase in progesterone and estrogen.

All of these symptoms are related to hormonal changes associated with your cycle, but they are definitely exacerbated by lifestyle factors. Essentially, PMS symptoms are the result of the balance between estrogen and progesterone. Remember that in the days leading up to menses, estrogen levels will rise and then will drastically fall. If we have excess estrogen to begin with, the drop of can be relatively noticeable. Similarly, if we do not have adequate progesterone in the days leading up to menses, we will really notice the effects of high progesterone.

So what can we do to counterbalance this? Let’s start by talking about the general state of your health. Having high inflammation levels can negatively affect your body’s ability to respond to progesterone, which will contribute to anxiety associated with PMS. So how do we reduce inflammation? Let’s start by reducing our stress AND avoiding alcohol; exercise can also have a beneficial effect against PSM symptoms (and bonus, it also helps to decrease anxiety).

We also want to be sure that we are appropriately metabolizing and removing excess estrogen from our system, because excess estrogen can cause breast pain, irritability and fluid retention (bloating). Then, when estrogen levels drop drastically, we can get migraine headaches. How do we reduce and stabilize estrogen? Glad you asked, fortunately, it is similar to the steps we take to promote progesterone responsiveness: avoid alcohol, limit intake of inflammatory foods, and maintain appropriate gut bacteria. Ultimately, we need to be sure that our liver is functioning appropriately to inactivate estrogen and then your bowel needs to be able to eliminate it. Minimizing your exposure to endocrine disrupting chemicals (e.g. pesticides and plastic softeners like BPA) will reduce the load on your liver so that it can give estrogen detoxification plenty of attention. Also, most PMS symptoms can be worsened by deficiencies in magnesium, zinc and vitamin B6, so you can try supplementing with these (see below).

Here are some other dietary strategies you can use to mitigate the effects of PMS:

  • Magnesium – I recommend starting with 200mg daily the week before your cycle starts.
  • Vitamin B – Supplement with B6 or eat foods rich in vitamin B, like spinach, almonds and fish.
  • Zinc – try a supplement, especially if you don’t eat a lot of read meat or shellfish.
  • Essential fatty acids (especially Omega-3s): Think fish oil and flax seeds.

Since there are so many of you that are athletes, I love to educate you about what to expect in terms of athletic performance surrounding your cycle. Let’s consider the hormonal implications on your body’s function, especially when it comes to exercise:

  • During menstruation your progesterone and estrogen are low, which means that hormonally we are actually in a favorable place when it comes to athletic performance. All of the energy our body was expending toward becoming pregnant can be directed elsewhere. Research has shown that women make greater strength gains when they train during this time!
  • 5 days before menstruation (PMS time) our estrogen and progesterone levels are super high, which means our body is NOT going to use carbs and is going to prefer to use fat. This is NOT the time to push it in the gym, and here’s why:
    • When estrogen levels are high, our bodies are in a glycogen-sparing state. Essentially, your body doesn’t want to use carbs because it wants to save them just in case you become pregnant and can’t find food (I mean, this was a serious concern for our biological predecessors).  Also, estrogen inhibits anabolism (muscle growth).
    • Progesterone increases muscle catabolism (muscle breakdown).
    • Also, it’s important to note that progesterone will act on another hormone system (aldosterone), which leads to a decrease in blood volume, which decreases our cardiac output (read: our ability to perform aerobic work will be decreased).
    • Lastly, we have an increased body temperature when progesterone levels are high, so we are going to feel hotter at baseline.

Bottom line: Skip your most intense workouts in the ~5 days leading up to your period and don’t beat yourself up if you don’t perform as well as you normally do. I personally find that I’m not able to lift as heavy and I have major struggles doing anything anaerobic (so WOD’s usually don’t feel too good). But listen, I’m not saying to skip your workout altogether. Remember, exercise is good for PMS symptoms, so just lower the intensity if your body isn’t feeling its best. Also, during this time make sure you are taking in complete protein sources BEFORE and AFTER your workouts (branched-chain amino acids are a great way to make this happen), and so are animal food sources (eggs, meat, etc.). Remember that most plant proteins are not complete proteins, so if this is how you get your protein, be sure to supplement with something that gives you leucine, valine and isoleucine (three essential amino acids that help make up almost one third of your muscle tissue; again, branched chain amino acids are a really easy way to supplement). Oh, and up your carb intake BEFORE your workouts!

I encourage every woman to start to track their cycle for a month or two. I’ve been using the app Dot and have been loving it! It really gives me a lot of insight into why I’m feeling the way that I do (tired, short fuse or extra hungry) so that I can listen to by body and treat it appropriately.

Thank you for following along! I hope that you continue to stick with me for the rest of the month, because in the coming weeks I will discuss hormone imbalances (including PCOS), how hormones change during pregnancy/postpartum, as well as lifestyle and dietary factors to promote hormonal balance and wellness.

Tune in next week when I talk about birth control – how it works, what it does to our bodies and what happens when we come off of it.

I’d love to hear from you! What questions do you have?

This Post Has 2 Comments

  1. Laura

    Love the info on hormones Amy, excited to hear more and understand what my body is going through postpartum ❤️

    1. Amy Osborne
      Amy Osborne

      Thank you SO much for reading, Laura! And I love to chat about postpartum, because the woman’s body goes through SO much during that time!

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