Premenstrual syndrome (PMS) describes a group of physical, emotional, and cognitive symptoms that arise in the second half of the menstrual cycle. It reflects the normal hormonal changes that occur across the cycle, combined with how sensitive the brain and body are to those changes.

Rather than being caused by “too much” or “too little” of a hormone, PMS is better understood as a heightened response to normal hormonal fluctuations.

This article explains what is happening across the menstrual cycle and how factors such as nutrition, stress, sleep, and lifestyle choices can influence symptom severity.

What is PMS?

PMS occurs during the luteal phase of the menstrual cycle (the time between ovulation and menstruation).

Common symptoms include:

• Irritability and low frustration tolerance
• Mood swings, anxiety, or low mood
• Fatigue and low energy
• Reduced confidence
• Breast tenderness
• Bloating and fluid retention
• Headaches or migraines
• Brain fog or difficulty concentrating
• Changes in appetite or cravings

These symptoms vary widely between individuals and cycles.

What is happening hormonally?

Before ovulation (follicular phase)

• Oestrogen rises as the ovarian follicles develop
• Progesterone remains low
• The uterine lining rebuilds

Many people feel more energised and emotionally stable in this phase, as oestrogen supports serotonin activity in the brain.

After ovulation (luteal phase)

• Progesterone rises significantly
• Oestrogen remains present but fluctuates
• The uterine lining is maintained

Progesterone is converted into a neuroactive compound that enhances gamma-aminobutyric acid, the brain’s main calming neurochemical.

GABA reduces brain excitability and supports calm mood, sleep, and emotional stability. This is why many people feel relatively balanced in the mid-luteal phase.

Just before menstruation

If pregnancy does not occur:

• Progesterone levels fall rapidly
• Oestrogen levels also decline

his sudden hormonal drop reduces calming brain signalling and increases sensitivity to stress, pain, and emotional triggers.

Importantly: PMS symptoms are driven less by absolute hormone levels and more by the speed and magnitude of hormonal change.

Why PMS symptoms happen

As hormones fall:

• Emotional regulation becomes less stable
• Stress sensitivity increases
• Pain and bloating are felt more strongly
• Energy levels drop

This creates the combined emotional, physical, and cognitive symptoms of PMS.

Why some people experience PMS more severely

Everyone experiences hormonal changes, but some people are more sensitive to them.

In some cases, the brain has an amplified response to normal hormone fluctuations. This can result in more intense symptoms.

Why healthy weight matters

Body fat plays an active role in hormone production.

Higher body weight

• Increases conversion of other hormones into oestrogen
• Raises oestrogen relative to progesterone
• Can worsen bloating, breast tenderness, and mood changes

Lower body weight

• Can reduce oestrogen levels
• May disrupt or suppress ovulation
• Leads to irregular progesterone production

Both extremes can lead to less stable hormone patterns and more noticeable PMS
symptoms.

Blood sugar and PMS

After ovulation, the body becomes less efficient at handling insulin. When blood sugar is unstable:

• Mood becomes more variable
• Energy levels fluctuate
• Cravings increase

Insulin also interacts with ovarian hormone production, meaning high or unstable insulin levels can affect hormone balance and worsen PMS symptoms.

Ovulation and cycle regularity

PMS depends on ovulation.

After ovulation:

• Progesterone is produced
• Emotional stability is supported

If ovulation is irregular:

• Progesterone production becomes inconsistent
• Hormone patterns become less predictable

Low body weight, stress, and insulin resistance can all interfere with ovulation.

Nutrition and PMS

Nutrition affects PMS through several key pathways:

Blood sugar stability

Stable meals reduce mood swings, fatigue, and cravings

Brain chemicals

Nutrients support the production of …

• Serotonin (mood regulation)
• Dopamine (motivation and reward)

Inflammation

Highly processed diets can increase inflammation, worsening cramps, headaches, and
fatigue.

Hormone production and breakdown

The body needs nutrients to produce and process hormones effectively.

Energy levels

Iron, magnesium, and B vitamins support energy production, especially important in the
luteal phase.

Fibre and oestrogen levels

Oestrogen is:

1. Processed by the liver
2. Released into the gut
3. Excreted in stool

Fibre helps by binding oestrogen in the gut and reducing its reabsorption. Without enough fibre, oestrogen can be reabsorbed back into the bloodstream, which may contribute to:

• Bloating
• Breast tenderness
• Mood changes

Lifestyle factors

Smoking

Affects liver breakdown of oestrogen and increases stress hormones, worsening irritability and fatigue.

Alcohol

Affects brain chemicals involved in mood regulation and disrupts liver processing of hormones, contributing to mood and sleep disturbance.

Stress

High cortisol affects the hormone system controlling ovulation, and increases sensitivity to hormonal changes.

Sleep

Poor sleep reduces emotional regulation, increases pain sensitivity, and raises cortisol, amplifying PMS symptoms.

Nutritional and supplement support

Some people find that certain supplements can help ease PMS symptoms alongside a healthy lifestyle. Evening primrose oil may support breast tenderness, while Double Magnesium can help with muscle cramps, headaches, fatigue, stress and sleep. Fibre-based products such as Fibre Plus or Super Protein with Fibre may support digestion and oestrogen metabolism, and multivitamins help cover key nutrients involved in hormone production and energy levels. More complete nutrition options like Daily Fuel or Soya Protein with Vitamins and Minerals can also support steady energy, weight support and blood sugar levels. BeYou Period Patches can also used for period pain relief.

Hormonal treatment and when to seek help

For some people, lifestyle changes are not enough. Hormonal treatments such as the combined contraceptive pill, patch, or vaginal ring work by preventing ovulation, which reduces the normal rise and fall of oestrogen and progesterone. This can stabilise symptoms in some individuals.

In more severe cases, especially where mood symptoms are significant, doctors may prescribe anti-depressants (either continuous or cyclically during the luteal phase only) to regulate brain chemicals.

You should see a GP if PMS:

• Disrupts daily life, work, or relationships
• Does not improve with sustained lifestyle changes
• Results in significant & overwhelming mood symptoms

Conclusion

PMS is not simply caused by “hormones going wrong.” It results from:

• Normal cyclical hormone changes
• Brain sensitivity to those changes
• Metabolic factors like insulin regulation
• Inflammation levels
• Lifestyle influences such as sleep, stress, nutrition, smoking, and alcohol

The menstrual cycle is a tightly regulated system. PMS occurs when the body’s response to that system becomes amplified.

The key message: You can’t stop the cycle, but you can influence how strongly it affects you.

To find out more click the links below:

• Evening Primrose Oil
• Magnesium
• Fibre Plus
• Super Protein with Fibre
• Daily Fuel
• Soya Protein
• Period Patches

Information and other content provided in these blogs should not be construed as medical advice and should not be considered a substitute for professional medical expertise. If you have any medical concerns, you should consult with your health care provider.