Also called functional amenorrhoea, hypothalamic amenorrhoea (HA) is one of the most common topics I am contacted about via email and social media, usually by women who say things like; ‘I haven’t had a period for over a year and I just can’t understand why. I exercise five times a week and I’m on a really healthy diet.’


Although I have no statistics to back this up, I would estimate that it is more common in young, fit women heavily invested in a healthy lifestyle. Unfortunately, the current fashion for an athletic physique, combined with the ‘more-is-more’ attitude of society and our hectic lifestyles leave little room for the simple things in life – like hormone production.

That is why women get HA; and I can usually tell this straight away from the Instagram profiles of the many women who message me about this problem – their bodies have quite simply run out of steam.

While we may not be very good at consciously prioritising the essentials, our bodies do this automatically as a way of helping us to survive. As over-the-top as it sounds, your body would prefer to keep your heart beating, rather than give you a period, so your brain shuts off production of the hormones that stimulate your ovaries, which stops ovulation.

And since the entire purpose of your menstrual cycle is for you to get pregnant, Mother Nature is particularly clever, recognising that a stressed-out woman does not need the added stress of having a baby. From an evolutionary point of view, this is a survival tactic for both mother and baby.

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The main triggers for hypothalamic amenorrhoea that I see on a recurrent basis are stress, diet and overexercising – or, usually, a combination of all three.

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You’ve probably heard of cortisol, the stress hormone. It influences production of female hormones by telling your brain that you’re under stress (even if you don’t realise it) and to halt ovulation until you’ve overcome it. Unfortunately, we are so used to living our lives in ‘turbo-power mode’ that we’ve forgotten what it’s really like to press the pause button, or even that it exists.

I frequently meet real-life superwomen. They typically have several children, a zoo-worth of animals and a husband who isn’t very domesticated. And often an irregular cycle.

Recently, I called one of these superwomen into my room and apologised that the clinic was running late. She said, ‘Oh, don’t worry; it’s been lovely to sit and read a magazine and have some time to myself...’ So before she’d even sat down I was pretty certain of what the problem was, although it can be a tricky one to solve because so many women have lost sight of how important it is to take that critical time for themselves.

Dietary factors

If you’re not eating enough to be able to provide the energy requirements of your own body, you’re not going to be able to sustain a healthy pregnancy. So here again, your brain shuts the system down, saving the energy and nutrients that would otherwise be used on ovulation.

Fat tissue is one of the sites of oestrogen production, so women with very low body fat may not produce enough oestrogen, which is made from a specific type of fat called cholesterol. Fat tissue is also able to send signals to the brain to tell it whether there is enough of the stuff to maintain a pregnancy. Female hormones are made of fats, so if your diet is devoid of good, healthy fats, your body doesn’t have the right ingredients to make the goods.

I recently had a difficult conversation with a patient who had become a vegan right around the time that her periods stopped, but she was convinced that couldn’t be the reason why, because to her, veganism was the healthiest diet out there. However, any extreme change in diet can lead to nutrient deficiency.


Adrenaline is the ‘fight-or-flight’ hormone that is going to save you from that wild bear. Nowadays, there are very few bears or other life-threatening mammals running around, but your body doesn’t know the difference between thrashing it out on the treadmill or running from said bear.

Your body senses this exertion as a stress and says to your ovaries, ‘Hold your horses! This woman is in danger – do not ovulate.’ It’s common for long-distance runners to lose their periods, but it’s not just running that can be a problem. Any intensive exercise can have the same effect.


Many women that I see are training like athletes, then running off to their full-time jobs, families and social commitments and it can be too much for their bodies to cope with. They can also be putting themselves in a calorie deficit if they’re not eating enough, which takes us back to dietary factors.

The Gynae Geek: Your no-nonsense guide to ‘down there’ healthcare by Dr Anita Mitra is out now (£14.99, Thorsons).
The Gynae Geek: Your no-nonsense guide to ‘down there’ healthcare by Dr Anita Mitra is out now (£14.99, Thorsons)


Dr Anita Mitra, BSc(Hons) MBChB PhD is an NHS doctor based in London working in Obstetrics & Gynaecology, with experience in both clinical medicine and research.