Everything You Need To Know About Amenorrhea

Trigger Warning: Please note this blog post discusses eating disorders.

Menstrual Cycles

I’m sure anyone who menstruates can appreciate the physical and mental pain associated with periods and although we may wish they’d go away – their absence can be a sign of a problem which requires investigation. 3-4% of people who menstruate will experience amenorrhea which is not caused by pregnancy or lactation[i], so it is evidently a really important issue that we should be discussing more openly.

The menstrual cycle is a complex (but fascinating) process which is governed by several hormones which help with the maturation of the egg cell, ovulation (the release of an egg from the ovary) and menstruation itself[ii].

It is important to be conscious of your own menstrual cycle and what is normal for you. Although an average cycle is 28 days, regular cycles can vary in length from 21-40 days and the length of bleeding can vary from 2-7 days[iii]. You may find it useful to document your menstrual cycle in an app or in your calendar, which can help you identify patterns or changes. Some apps also allow you to include any period-related symptoms such as acne and bloating too. If you visit a GP about your period, they will often ask for a menstrual history so this can be really helpful.


Primary amenorrhea is a failure to start menstruation by the age of 14-16[iv].

Secondary amenorrhea is the type we will be discussing and is clinically defined as:

1. The absence of periods for 3 months if you have a regular cycle

2. 6 months if you have an irregular cycle[v] (not due to menopause).

It is important to note that if you’ve started your period recently it may take a while for things to settle down and regulate[vi].

Lactational Amenorrhea is the absence of periods during lactation (breastfeeding). This is our body’s protective way of preventing pregnancy so quickly after giving birth due to its intense physical and nutritional demands.


Menstruation is easily derailed by physically and/or emotionally stressful environments, and, like lactational amenorrhea, is an adaptive response to prevent pregnancy in unfavourable environments.

Examples of stress include:

• Physical Stress Excessive exercise which may be part of training regime as a professional athlete and is therefore specifically referred to as ‘athletic amenorrhea.’

• Eating Disorders

• Weight Change

• Emotional Stress

Weight Changes

So, how and why does our body weight influence our menstrual cycles? Energy is derived from the food we eat and is required for every bodily function. Body fat is our ‘energy reserve’ and may be depleted in those with eating disorders, in athletes or those on prolonged, restrictive diets which result in rapid, significant weight loss.

A reduction in energy availability results in a diversion of the limited resources away from reproduction to essential bodily functions such as heart rate and breathing. Kisspeptin has been identified as a mediator which monitors energy reserves (body fat) and subsequently curbs reproductive function[vii] through reducing the levels of hormones which trigger your period[viii]. Long term, this may affect fertility[ix].

Positively, with long-term weight recovery for those with eating disorders, amenorrhea is largely reversible[x].

Additionally, weight gain in those who have experienced weight loss* is sufficiently remedial for the reversal of amenorrhea. Some foods worth considering if seeking to gain weight safely and nutritiously include:

• Use full-fat products such as milk and yoghurt – you can switch back once your weight has been built up

• Use unsaturated oils such as olive and sunflower oil in cooking

• Choose energy dense foods such as nut butters as a snack with fruit in between meals

• Choose oily fish at least once a week – this includes salmon and mackerel

• Base meals on starchy carbohydrates and vegetables

• If you get full quickly, smaller, more frequent meals may be helpful

Bone Health

The hormone oestrogen surprisingly plays a vital role in maintaining bone health. Absence of a period indicates oestrogen insufficiency which can have lasting effects on our skeletal health, leading to an increased risk of fractures later in life[xi].

Peak bone mass is defined as reaching the maximum amount of bone tissue in the skeleton and is reached in late adolescence (around 18). It can be achieved and maintained through weight bearing exercise such as running or weightlifting, alongside a diet rich in vitamin D and calcium.

Polycystic Ovary Syndrome

Amenorrhea is a symptom of polycystic ovary syndrome (PCOS). PCOS is associated with an insulin resistant state where circulating levels of insulin (the hormone which allows your body’s cells to use glucose) are increased. This has been shown to impede ovulation.

Although insulin resistance is typically associated with higher BMIs, it can occur regardless of weight[xii] and may in fact be a cause of weight gain rather than an effect[xiii]. Therefore, diet and exercise to correct insulin resistance may only be beneficial in some individuals. Promisingly, as little as 5% weight loss can lead to significant improvements[xiv].

Seeking Help

* Please note advice for gaining weight is not a substitute for seeking medical advice, especially if there are concerns about eating disorders.

Please refer to your GP if you would like to speak to someone about an eating disorder. BEAT is a really helpful charity whose website offers confidential and free support and information about eating disorders. The helplines are listed below but they can also be contacted through webchat, email and DM on Instagram, Twitter or Facebook.


Helpline: 0808 801 0677

Studentline: 0808 801 0811

Youthline: 0808 801 0711

BEAT: https://www.beateatingdisorders.org.uk/support-services/helplines

This blog post was written by Alannah is a Food Science and Nutrition graduate from the University of Leeds who is currently studying for an MSc in Clinical and Public Health Nutrition at UCL. Her interests are cooking and more recently “myth busting” which challenges our perceptions of food, nutrition, and health. You can find her Instagram at @alannah_eats.


[i] https://cks.nice.org.uk/topics/amenorrhoea/background-information/prevalence/

[ii] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2913133/

[iii] https://www.nhs.uk/conditions/periods/fertility-in-the-menstrual-cycle/



[vi] https://adc.bmj.com/content/archdischild/97/6/554.full.pdf

[vii] https://pubmed.ncbi.nlm.nih.gov/18634841/

[viii] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5998335/

[ix] https://www.nhs.uk/conditions/infertility/

[x] https://pubmed.ncbi.nlm.nih.gov/9006523/

[xi] https://pubmed.ncbi.nlm.nih.gov/14501240/

[xii] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4334071/

[xiii] https://www.nhs.uk/conditions/polycystic-ovary-syndrome-pcos/causes/

[xiv] https://www.nhs.uk/conditions/polycystic-ovary-syndrome-pcos/treatment/

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