Unfortunately in school most of us were not taught about the effects of our menstrual cycle. Moodiness, sweet cravings, breakouts, weight gain… it’s a joy, right? I have had my fair share of menstrual cycle-related issues but learning about how hormones work and how they affect us helped me to navigate the complicated world of womanhood.
What is the menstrual cycle?
The medical definition of the menstrual cycle is: The monthly cycle of changes in the ovaries and the lining of the uterus (endometrium), starting with the preparation of an egg for fertilization. When the follicle of the prepared egg in the ovary breaks, it is released for fertilization and ovulation occurs.
In simple terms, the menstrual cycle is the name for the cyclical hormonal changes experienced by fertile women as the body prepares itself for a possible pregnancy. The length of the menstrual cycle lasts on average 28 days (but it can be up to 40 days), before the cycle repeats, unless an egg is fertilized.
The menstrual cycle starts at menarche (puberty) and continues until menopause, except during pregnancy.
The phases of the menstrual cycle
The female menstrual cycle is divided into two to four phases (depending on your source):
- menstrual phase
- follicular phase
- ovulation phase
- luteal phase
During each phase, different changes happen in your body. These changes are regulated by the endocrine system – specifically the hypothalamus and pituitary gland – that releases specific hormones to prepare the body for a possible pregnancy. These hormonal changes can greatly affect behavior and mood, including eating and exercise habits, and metabolic processes, which we will come onto later. But for now, let’s take a deeper look into the hormonal changes that occur in each phase of the menstrual cycle.
The hormones of the menstrual cycle
The menstrual cycle can be separated into two main phases: the follicular phase (before ovulation) and the luteal phase (after ovulation). The other two sub-phases of the menstrual cycle – ovulation and menstruation occur as a result of the hormonal changes that happen in the follicular and luteal phases.
The hormones you need to know about in relation to the menstrual cycle are:
- Sex hormones – estrogen, progesterone and testosterone
- Luteinizing hormonen (LH)
- Follicle-stimulating hormone (FSH)
What happens during each phase?
During the follicular phase, levels of estrogen and progesterone start low, and steadily increase up until ovulation, then rapidly decline. Midway through the luteal phase, progesterone and estrogen spike, but then if the egg isn’t fertilized, estrogen and progesterone levels decrease and a period begins. Testosterone, an anabolic sex hormone, naturally found at low levels in women, maintains a steady level throughout the menstrual cycle, with a spike during ovulation. See graph 1 to see this in action.
Graph 1 – Stages of the Menstrual Cycle – Source: Women in Balance Institute, National University of Natural Medicine
LH and FSH, produced by the pituitary gland, promote ovulation and stimulate the ovaries to produce estrogen and progesterone. As shown in graph 2, FSH levels are initially high, during menstruation and the follicular phase, this is to develop follicles. LH (and to a lesser extent, FSH) see a sharp increase in the later part of the follicular phase, which triggers ovulation. Due to the rising levels of estrogen in the luteal phase, FSH and LH are inhibited.
Graph 2 – LH and FSH in Menstrual Cycle – Source: https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/66-hormones-homeostasis-and/menstrual-cycle.html
Symptoms of the menstrual cycle
Women go through a number of changes throughout the menstrual cycle (not just the changes in their uterus!). The other changes, also caused by the changing levels of hormones, can manifest mentally, physically or emotionally.
The symptoms of the menstrual cycle are well-established in research, including:
- Breast sensitivity
- Abdominal cramps
- Water retention
- Mood swings – specifically low mood, crying, irritability
- Sleeping problems
- Digestive issues like bloating
- Breakouts
- Fatigue
- Headaches
- Muscle pain
These symptoms typically occur just before and during the period. Many of the mood-related symptoms are caused by a sharp decline in estrogen, which has an impact on certain neurotransmitters in the brain like dopamine and serotonin – both associated with happiness and contentment. Without enough estrogen, the function of these neurotransmitters is inhibited, resulting in feeling sad or emotionally vulnerable.
Other symptoms like fatigue, muscle pain, and an increased appetite are also connected to the changing levels of hormones, and because of an increase in your metabolic rate, leading up to and during your period.
A 2003 study found that resting metabolic rate (RMR) varies widely across the menstrual cycle. Some women experienced a 10 percent increase in their metabolic rate, which means you are burning through energy more quickly, which can result in hunger and/or tiredness.
Why do some women experience more severe premenstrual symptoms than others?
As outlined in a study published in the American Journal of Epidemiology, the severity of the symptoms you experience depends on a number of factors including:
- Other hormonal disturbance
- Smoking
- Physical activity
- Diet
- Alcohol and caffeine consumption
- Ethnicity
- Stress levels
- BMI
- Age
While some of these factors are unavoidable, e.g. your age and ethnicity, the majority of the factors that influence the severity of symptoms are modifiable. If you suffer badly with premenstrual symptoms, you may want to make some dietary and lifestyle adjustments to feel like your best self during all times of the month. To learn more about the adjustments you can make, check out the Omnom Delicious blog post about naturally rebalancing hormones.
The menstrual cycle might seem like a major inconvenience to you, but it’s also the best gift: it facilitates women’s ability to create life! We hope this article has helped break down everything you need to know about the menstrual cycle and the hormones involved that affect the changes your body goes through.
To learn more about the menstrual cycle and hormones, please subscribe to our blog for weekly blog posts!