Physiology of the Menstrual Cycle: Understanding the Root of Hormonal Imbalances Written by: Dr. Lauren Goss, ND

As a naturopathic doctor, one of our main guiding principles is doctor as teacher. I truly believe the more we know about our bodies and understand our physiology, the more we can work with and celebrate bodily changes, rather than being constantly disappointed.

As cycling people, our bodies are always in hormonal flux. It’s not just the monthly cycle, but the daily, weekly and larger transitional changes. Expecting ourselves to think, perform, look and feel the same every day is only setting us up for a lifetime of frustration and discomfort. It is always my goal with patients to inform and encourage a relationship, with our bodies and hormones, that allows us to be compassionate, understanding, and caring. Physiological hormonal changes can be challenging in the best of times, the addition of hormonal imbalances that are often unexplained and under validated, can have huge impacts on your day-to-day quality of life.

With an average of 450 menstrual cycles in a lifetime[i], that’s approximately 2250 days of bleeding, we need to do everything we can to ease unnecessary suffering. Symptoms such as severe cramping (dysmenorrhea), heavy bleeding (menorrhagia), extreme mood changes, acne, hormonal migraines, painful fibrocystic breasts, to name a few, are often dismissed as being normal. Just because something is common, does not mean it is normal. Let’s work together to educate, empower, and dig a little bit deeper towards finding the root cause of hormonal imbalances.


Naturopathic doctors have often referred to the menstrual cycle as the fifth vital sign; after blood pressure, heart rate, respiratory rate and temperature. Meaning, our menstrual cycle gives us great insight into our overall health. How are we sleeping? How are we managing stress? How are we eating? What are our exercise levels (too little or too much)? How are our individual health conditions impacting us? Let’s take a look at the menstrual cycle, our main hormones, the incredible physiological roles they play, and see how the liver and gut can help or hinder hormonal imbalances. By understanding the root of these hormonal imbalances, I hope this creates a foundation of love and acceptance of the menstruating form and all the strength and power that comes with it.


The Menstrual Cycle:

First, let’s breakdown what is happening in each phase of the menstrual cycle. Take a look at the pituitary (FSH and LH) and ovarian (estrogen and progesterone) hormones in the middle of the above graph, which represents the average 28 day cycle. The follicular phase, includes menses, and starts on day 1 of bleeding (not spotting), continuing until ovulation. You can see that hormones are relatively low during most of this phase, which is often a time when hormonal symptoms subside and energy levels are on the rise.


Estrogen is the main hormone of the follicular phase, helping to build the endometrial lining and develop the follicle, which will eventually release the egg. Okay, it’s not quite that simple, so please bear with me for a bit of biochemistry. There are two types of cells in the ovaries: theca and granulosa cells. The luteinizing hormone (LH), from the anterior pituitary gland (in the brain), stimulates theca cells, by activating an enzyme, to produce progesterone and androstenedione. Androstenedione continues on to the nearby granulosa cells, where the follicular stimulating hormone (FSH) (also from the brain), comes in and tells these cells to covert the recently produced androstenedione to testosterone and then 17-beta-estradiol. The famous (or infamous) aromatase enzyme is responsible for this very important conversion. The resulting progesterone and 17-beta-estradiol, will then fluctuate in levels based on where you are in your cyclei.


Ovulation happens midcycle, approximately day 14 in a 28 day cycle, when 17-beta-estradiol is at its highest, and the pituitary gland releases maximum amounts of LH and FSH. This rise is referred to as the LH surge, which stimulates the follicle that estrogen just worked so hard to develop, to release an egg. Once the egg is released, estrogen levels begin to fall and LH and the corpus luteum, which is an ovarian structure where the follicle ruptures, take over the role of producing progesterone. Progesterone, is now the main character of the luteal phase, helping to prepare the endometrial lining for potential egg implantation. This is a high hormone phase, as hormones will rise and then begin to fall to signal the lack of implantation and tell the body to shed the lining and start the whole process over again.


Please pause for a moment and acknowledge how much work your body is doing EVERYDAY for a chance of reproducing. Picture yourself going about your day and these little worker bees in your body are in constant communication and creation. The complexity and capacity of the menstruating form is truly incredible! The hormones also do so much more than reproduction, so let’s get to know them a little bit better.


Hormones – Who are they and what do they do? 

First of all, by taking a look at the network of steroid hormones in our bodies (both sex and stress hormones), you can see that estrogen (estradiol being 1 of 3 estrogens), progesterone, and testosterone, get a lot of credit but there are many more intermediaries and metabolites involved. The interconnection of the stress hormones, mainly cortisol, and the sex hormones is important to note and helps us understand the hormonal impact of physiological stress. Also, please note, cholesterol is the building block for all of these hormones, so giving your body the proper resources is the first step to preventing imbalances!



Estrogen gets a bad reputation for being the cause of many of our unpleasant hormonal symptoms and conditions. Estrone (E1), estradiol (E2) and estriol (E3) all have specific functions and the ratios and metabolism of these will impact hormonal symptoms. Estradiol is the most important for the menstrual cycle and the amounts of all 3 is an important indicator of estrogen health. Beyond reproduction, estrogens have a plethora of additional functions.  They play a role in blood sugar maintenance, control cholesterol levels, assist in the production of neurotransmitters and other hormones (serotonin and melatonin), are needed for proper bone development, support skin and hair health, and are needed to maintain urinary tract and vaginal tone[ii]. We often focus on avoiding too much estrogen, however, the balance and forms are crucial, because without it all of the above would be jeopardized. Therefore, both high and low estrogen levels can be linked to common hormonal symptoms and gynecological conditions[iii]. Estrogen specific conditions include: uterine fibroids, endometriosis, uterine and breast cancers. Symptoms of higher or unopposed estrogen (normal estrogen but low progesterone) include breast tenderness, swelling, heavy bleeding, and severe crampingii.



As discussed above, progesterone is most well-known for its role in preparing the body for implantation and pregnancy. It also has a role in maintaining libido and is known to be neuroprotective, with an increasing number of studies on Alzheimer’s protectioniv. When mood changes happen pre-menses, such as depression, anxiety, and irritability, it may be due to decreasing progesterone levels; therefore, if levels are low, these symptoms may exacerbated[iv]. If cycles are longer than 35 days, it is likely that ovulation did not occur. Remember, you can still have a period without ovulating, so looking for signs of ovulation is important. If there was an anovulatory cycle, not only are there fertility concerns, but there will likely be a progesterone deficiency, as the corpus luteum is a main source of progesterone in the luteal phase of the cycle. There are many reasons for anovulation, it is crucial to find the root cause. Progesterone is also needed to help balance out estrogen levels, so estrogen can do all it’s important roles without wreaking havoc elsewhere!


Testosterone / Androgens:

Testosterone and androgens are our male sex hormones, which everyone has, just in varying amounts. As previously mentioned, when we lack certain enzymes, we can’t convert testosterone into estradiol and therefore will have more testosterone and potentially convert that into DHT. When these hormones are higher we can have male pattern hair growth, acne, potentially lack ovulation and therefore increase the risk of developing ovarian cysts.


The metabolism and excretion of hormones is also very crucial, as they can get reabsorbed through the digestive tract and can end up recirculating. Therefore, a healthy liver and gut are very important with any underlying hormonal imbalances.



Liver and Gut Health – what are these heroic detoxifiers up to? 

Both the liver and the digestive system are crucial in helping to maintain healthy hormones, as they both play a role in metabolism and excretion. The liver is involved with 80-90% of hormones in the body. Specifically, 50% of estrogens get metabolized in the liverii. The liver helps to inactivate them by attaching glucuronic acid to the estrogens, excretes the metabolites into the bile, which gets transported into your small intestine and ready for departureiii.

If the liver is congested or lacking enzymes required for detoxifying or if your bowels aren’t moving daily, these estrogen metabolites will sit there, getting reabsorbed and recirculate through your blood stream, increasing unwanted estrogen levels. Our large intestine is also the home of our microbiome and certain bad bacteria secrete a molecule called beta glucuronidase that recycles estrogens rather than getting rid of it. Your liver, gut health and your microflora, have a huge role in maintaining healthy hormone levels.


Not only is our gut flora important but so is our vaginal flora, which is heavily influenced by healthy gut bacteria. It has a natural acidic pH, ranging from 3.5-4.5 and lactobacillus has a strong role in helping to maintain this pH, by producing lactic acid. Vaginitis is often due to an imbalance of healthy flora and estrogen supports lactobacillus, hence why declining estrogen levels can cause vaginitis (post-menopausal, post-partum, yeast infections prior to menses). Supporting overall digestive health and therefore your microbiome, will have positive impacts on hormonal health!


Hormones are complicated. They are heavily influenced by our overall health and they, in turn, have a huge impact on how we live. Please seek the information needed to understand your individual cycles and hormones, especially if you have a hormone related condition. Ask questions, seek testing, and incorporate a holistic approach to understand all the influencing factors. Start with the basics – liver support, optimize digestion, and stress management. Remember, just because it is common, doesn’t mean it is normal!


Happy hormones everyone,

 Dr. Lauren Goss, ND



[i] Thiyagarajan DK, Basit H, Jeanmonod R. Physiology, Menstrual Cycle. [Updated 2021 Oct 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:

[ii] Romm, A. High Estrogen: What It Means and What You Can Do. Accessed on June 9, 2022. From:

[iii] Patel S, Homaei A, Butchi Raju A, Meher B. (2018). Estrogen: The necessary evil for human health, and ways to tame it. Biomedicine & Pharmacotherapy, Volume 102, 2018, Pages 403-411, ISSN 0753-3322,

[iv] Taraborrelli, S. (2015). Physiology, production, and action of progesterone. Acta Obsetetricia Gynecologica Scandinavica, 94 Suppl 161, 8 -16.

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