Your menstrual cycle is more than just 'that time of the month'. It's a powerful, natural process that reflects your body’s rhythm and balance. Governed by a symphony of hormones, the cycle impacts everything from your energy and mood to your skin and metabolism. Understanding the science behind it can help you tune in to your body and make the most of each phase. Let’s dive into what’s happening behind the scenes and how it affects your everyday life.

Get to know your hormones

Oestrogen

Oestrogen is the primary female sex hormone, critical for reproductive health, sexual development, and overall well-being. It regulates the growth and maintenance of the reproductive tissues, including the uterus, ovaries, and vagina. Beyond reproduction, oestrogen supports bone density, cardiovascular health, skin elasticity, and mood stability.

Role in the Menstrual Cycle:

  • Follicular Phase: Oestrogen levels rise as the follicles develop in the ovaries, preparing the uterine lining (endometrium) for potential implantation. This surge peaks just before ovulation.
  • Ovulation: The oestrogen surge triggers a rise in luteinising hormone (LH), which facilitates the release of the mature egg.
  • Luteal Phase: Oestrogen levels drop after ovulation but remain moderately elevated to support the luteal function. If fertilization doesn’t occur, levels decline, leading to menstruation.

Progesterone

Progesterone is essential for maintaining pregnancy and regulating the menstrual cycle. It works to prepare the endometrium for implantation and supports early pregnancy by inhibiting uterine contractions. It also balances oestrogen's effects, providing calming and anti-inflammatory benefits.

Role in the Menstrual Cycle:

  • Follicular Phase: Progesterone levels remain low.
  • Luteal Phase: After ovulation, the corpus luteum secretes progesterone to stabilise the uterine lining and create a supportive environment for potential embryo implantation.
  • Menstrual Phase: If pregnancy doesn’t occur, progesterone levels drop sharply, triggering the shedding of the uterine lining (menstruation).

Follicle-Stimulating Hormone (FSH)

FSH is crucial for ovarian follicle development. It stimulates the growth of ovarian follicles, which house the eggs, and drives oestrogen production.

Role in the Menstrual Cycle:

  • Follicular Phase: FSH promotes the development of several follicles, one of which becomes dominant and releases oestrogen.
  • Ovulation: The rise in oestrogen from the dominant follicle feeds back to suppress FSH secretion, ensuring only one follicle ovulates.

Luteinising Hormone (LH)

LH is key for ovulation and the formation of the corpus luteum. It also stimulates the ovaries to produce oestrogen and progesterone.

Role in the Menstrual Cycle:

  • Ovulation: A mid-cycle surge in LH, triggered by high oestrogen levels, leads to the release of a mature egg from the dominant follicle.
  • Luteal Phase: LH supports the transformation of the ruptured follicle into the corpus luteum, which produces progesterone.

Additional Functions:

  • Regulates production of oestrogen and progesterone.
  • Essential for maintaining ovarian and reproductive health.

Other Important Hormones

CORTISOL: Known as the "stress hormone," cortisol is produced by the adrenal glands and plays a role in the body’s stress response. It regulates metabolism, blood sugar levels, inflammation, and energy availability.

Role in Women’s Health:

  • Chronic stress and elevated cortisol can disrupt the menstrual cycle by suppressing FSH and LH, potentially leading to irregular periods or amenorrhea.
  • Cortisol imbalances can exacerbate symptoms of PMS and perimenopause.


TESTOSTERONE: Though often associated with men, testosterone is vital for women’s health. It supports libido, bone strength, mood, and muscle mass.

Role in Women’s Health:

  • Imbalances, particularly high testosterone levels, can lead to symptoms like acne, hirsutism, and irregular cycles (e.g., in polycystic ovary syndrome, PCOS).
  • Testosterone levels naturally fluctuate throughout the menstrual cycle and decline with age.


THYROID HORMONES (T3, T4): Thyroid hormones, produced by the thyroid gland, regulate metabolism, energy production, and overall cellular function.

Role in Women’s Health:

  • Hypothyroidism (low thyroid function) can cause menstrual irregularities, heavier periods, or infertility.
  • Hyperthyroidism (overactive thyroid) may lead to lighter or absent periods.
  • Thyroid dysfunction is closely linked to other hormonal imbalances, including oestrogen and progesterone.


INSULIN: Regulates blood sugar by promoting glucose uptake into cells.

Impact: Insulin resistance, often seen in PCOS, disrupts hormonal balance, leading to irregular cycles, weight gain, and fertility issues.

ANTI-MULERRIAN HORMONE(AMH):

  • Function: Reflects ovarian reserve by indicating the number of available follicles.
  • Impact: AMH levels are used to assess fertility potential and ovarian health.


OXYTOCIN:

  • Function: Known as the "love hormone," it fosters bonding and reduces stress.
  • Impact: Oxytocin influences mood and can ease menstrual cramping by reducing stress.

PROLACTIN:

  • Function: Stimulates milk production in breastfeeding and regulates the immune system.
  • Impact: Elevated prolactin (hyperprolactinemia) can suppress FSH and LH, disrupting ovulation and causing irregular periods or infertility.


DHEA (Dehydroepiandrosterone):

  • Function: A precursor hormone converted into oestrogen and testosterone.
  • Impact: Supports energy, libido, and hormonal balance. Declines with age, particularly during menopause.

Understanding the Root Causes of Hormonal Imbalance

Hormones are influenced by what you put into your body, your environment, and how you care for yourself. When these factors are off balance, it can disrupt the delicate hormonal harmony. Let’s break it down:

  • Micronutrient Depletion

  • Hormone Disruptors

  • Neglecting Your Infradian Rhythm

Your endocrine system—the network responsible for hormone production—relies on specific micronutrients to function optimally. However, many factors can deplete these essential nutrients:

  • Synthetic birth control, chronic stress, and an imbalanced diet are common culprits.
  • Over time, the degree of micronutrient depletion can directly influence the symptoms you experience, whether it’s fatigue, mood swings, or irregular cycles.

Modern life is full of chemicals that interfere with our hormonal health:

  • Household cleaners, skincare, and beauty products often contain endocrine-disrupting chemicals that impact hormonal balance.
  • Caffeine and alcohol—while commonly used for energy or relaxation—can destabilize hormone levels over time.
  • Even birth control and hormone replacement therapies alter how your endocrine system functions naturally.

Opposite to men, women's body operates on more than just a 24-hour cycle (circadian rhythm); as a woman, you also have an infradian rhythm, which spans your monthly cycle. Ignoring this rhythm can lead to unnecessary strain on your hormones:

  • Exercise: Most women stick to the same workouts all month, but your body’s needs shift during different phases. Some phases benefit from intense activity, while others require gentler movement.
  • Diet: Eating the same way throughout the month doesn’t align with your body’s changing nutritional needs. Your hormones thrive on phase-specific nourishment.

Scientific Evidence Supporting Phase-Based Lifestyle Adjustments

Your hormones naturally ebb and flow in sync with your infradian rhythm—a biological cycle unique to women. Over a typical 28-day cycle, you move through four distinct phases, each marked by hormonal shifts that impact everything from your body temperature and skin elasticity to your energy levels, emotions, sleep patterns, and cognitive function.

  • HORMONAL IMPACT ON METABOLISM

    Estrogen increases insulin sensitivity during the follicular phase, promoting efficient energy use (Barr et al., 2021).

    Progesterone in the luteal phase can increase appetite and cravings due to its effect on blood sugar levels (Campbell et al., 2019).

  • EXERCISE PERFORMANCE

    Studies show that women may perform better in strength and endurance exercises during the follicular and ovulatory phases due to higher estrogen levels, (Sung et al., 2014).

    In contrast, moderate exercises in the luteal phase prevent overexertion when recovery is slower (McNulty et al., 2016).

  • MOOD REGULATION

    Estrogen’s role in serotonin production enhances mood and cognitive function during the follicular and ovulatory phases (Epperson et al., 2020).

    Lower estrogen and rising progesterone in the luteal phase can lead to PMS symptoms, mitigated by self-care and diet adjustments (Yonkers et al., 2017).

  • STRESS AND SLEEP

    Higher cortisol sensitivity in the luteal phase makes stress management crucial (Kirschbaum et al., 2015).

    Progesterone promotes deeper sleep but may also cause restlessness in the late luteal phase. Maintaining consistent sleep routines is key (Baker et al., 2019).