Is Your Menstrual Cycle Trying to Tell You Something?
For many women, a menstrual cycle is simply viewed as a monthly inconvenience. As long as periods are still arriving, it's easy to assume everything is working as it should.
In reality, your menstrual cycle is one of the most valuable indicators of your overall health. Changes in the timing, flow or symptoms of your period can provide important clues about your hormones, nutrition, stress levels and general wellbeing.
For active women, the menstrual cycle is often described as a vital sign. Changes in your cycle can be one of the earliest indicators that your body is under stress, whether from inadequate nutrition, excessive training, illness, psychological stress or an underlying medical condition.
Many people assume there are only two possibilities: either your periods are normal, or they stop altogether (amenorrhoea). However, menstrual health exists on a spectrum, and subtle changes often appear long before periods disappear completely.
Recognising these early signs can help identify problems sooner, allowing them to be addressed before they begin to affect fertility, bone health, athletic performance or long-term health.
Menstrual health is a spectrum
Rather than thinking of menstrual cycles as simply "normal" or "abnormal", it is more helpful to view them as existing along a continuum.
At one end is a healthy, regular cycle. At the other is complete loss of periods. Between these two extremes are many changes that deserve attention, even if you are still menstruating every month.
What does a healthy menstrual cycle look like?
Although every woman is different, a healthy cycle generally has the following features:
Cycle length between 24 and 38 days
Reasonably predictable timing from month to month
Bleeding lasting around 3–7 days
Moderate flow that is neither excessively heavy nor very light
Regular ovulation
Mild, manageable symptoms around menstruation
Small variations are entirely normal, but significant changes from your usual pattern are worth paying attention to.
Early warning signs that are often overlooked
Many women continue to have regular periods while subtle hormonal changes are already developing.
Examples include:
Cycles gradually becoming longer or shorter
Ovulation occurring much later than usual
Shortened luteal phase (the time between ovulation and your next period)
Increasing spotting before periods
Much lighter bleeding than previously
Loss of fertile cervical mucus
Worsening premenstrual symptoms
Reduced libido
Increasing fatigue
Slower recovery after exercise
Recurrent injuries or declining athletic performance
These changes are often dismissed as "just stress", "getting older" or "normal for me", but they may represent early signs that the body is under strain.
Painful periods are not always 'normal'
Many women have been told that period pain is simply something they have to put up with. While mild cramping is common, severe or worsening pain should never be ignored.
Painful periods (dysmenorrhoea) that interfere with work, school, exercise or daily life deserve proper assessment. They may be caused by conditions such as endometriosis or adenomyosis, but they can also occur alongside hormonal imbalances or other gynaecological conditions.
Similarly, excessively heavy periods, bleeding between periods or bleeding after sex should always be discussed with a healthcare professional.
Low energy availability: it doesn't have to be extreme
One of the most common reasons I see menstrual cycles change, particularly in active women, is low energy availability (LEA).
Low energy availability simply means that your body doesn't have enough energy left over to support all of its normal functions after accounting for exercise and daily activity.
Importantly, this doesn't necessarily mean you have an eating disorder, are underweight, or are deliberately restricting calories.
In fact, many women are eating what they believe is a healthy diet and maintaining a healthy body weight, but are simply not consuming enough energy to meet the demands of their training, work and everyday life.
This can happen in many ways, for example:
Regularly training fasted without adequately replacing energy afterwards.
Exercising several times per week while unintentionally under-eating.
Skipping meals because of a busy lifestyle.
Trying to lose weight while maintaining a high training load.
Following restrictive diets that make it difficult to eat enough.
Returning to exercise after illness without increasing food intake.
Looking after young children while juggling work, family life and exercise, leaving little opportunity to eat regularly.
Rather than switching reproduction off overnight, the body often adapts gradually. Menstrual changes may be one of the earliest signs that there is insufficient energy available to support optimal hormonal function.
Many women continue to have periods, but notice that their cycles become longer, ovulation occurs later, bleeding becomes lighter, cervical mucus disappears or premenstrual symptoms change. These subtle alterations are often overlooked because menstruation is still occurring.
If low energy availability continues over time, hormonal disruption may progress, increasing the risk of impaired fertility, reduced bone density, recurrent injuries, poorer recovery, fatigue and ultimately the loss of menstrual periods altogether.
The important message is that you do not have to lose your periods to be experiencing the effects of low energy availability. Early changes in your menstrual cycle may be your body's first indication that your energy intake is no longer keeping pace with its demands.
More significant menstrual dysfunction
As hormonal disruption progresses, changes often become more obvious.
These may include:
Cycles consistently longer than 35–45 days
Frequently skipped periods
Irregular or absent ovulation
Very infrequent periods
Marked changes in bleeding pattern
These changes should prompt medical assessment to identify the underlying cause rather than simply accepting them as part of training, stress or ageing.
When periods stop altogether
Amenorrhoea refers to the absence of menstrual periods.
Secondary amenorrhoea is defined as:
No periods for three months in a woman who previously had regular cycles, or
No periods for six months in someone whose cycles have always been irregular.
Although many people associate amenorrhoea with athletes, it is not a normal consequence of exercise or weight loss and should always be investigated.
Why else might your menstrual cycle change?
Low energy availability is only one possible cause of menstrual dysfunction.
Other common causes include:
Psychological stress
Polycystic ovary syndrome (PCOS)
Thyroid disorders
Elevated prolactin levels
Perimenopause
Certain medications
Significant illness
Rapid changes in body weight
This is why it is important not to self-diagnose. While lifestyle factors may play a role, changes in your menstrual cycle deserve a proper assessment to identify the underlying cause.
Why does this matter?
Your menstrual cycle reflects far more than reproductive health.
Hormonal disruption can affect:
Bone health and future osteoporosis risk
Fertility
Exercise performance
Recovery from training
Injury risk
Muscle adaptation
Mood and mental wellbeing
Concentration and cognitive function
Long-term cardiovascular health
In many women, the menstrual cycle is one of the earliest signs that the body is struggling to meet the demands being placed upon it.
Listening to those signals early gives you the opportunity to make changes before more significant health consequences develop.
When should you seek advice?
It is worth seeking medical advice if you notice:
A significant change from your usual cycle.
Cycles consistently outside the normal range.
Repeated skipped periods.
Very painful periods.
Heavy menstrual bleeding.
Bleeding between periods or after sex.
Difficulty becoming pregnant.
Persistent fatigue alongside menstrual changes.
Recurrent stress fractures or repeated injuries.
Declining performance despite training well.
Early assessment can often identify reversible causes and help prevent longer-term health consequences.
The bottom line
Your menstrual cycle is much more than a monthly period—it is an important indicator of your overall health.
You do not have to lose your periods completely before something is wrong. Small changes in cycle length, ovulation, bleeding patterns or symptoms may be your body's way of signalling that something needs attention.
Whether the cause is low energy availability, stress, an underlying medical condition or a hormonal disorder, recognising these changes early gives you the best opportunity to protect your long-term health, fertility and performance.
If you've noticed changes in your menstrual cycle, or you're struggling with fatigue, recurrent injuries, painful periods or concerns about your hormonal health, don't ignore them. A thorough assessment can help identify the underlying cause and create a personalised plan to support both your immediate wellbeing and your long-term health.
ABOUT DR KERRY ASTON
Dr Kerry Aston is a Consultant Rheumatologist based in Belfast, working in women’s health, fatigue, autoimmune conditions and complex symptoms.
She focuses on helping patients understand the underlying physiology driving their symptoms, particularly when conventional investigations have not provided clear answers.
Consultations are available at Beechill Clinic in South Belfast.