What is ‘cycle syncing’, and how might it affect menstruation?

Menstruation is once again a hot topic on social media, thanks to a new health trend known as “cycle syncing”.

It involves aligning your diet and exercise habits to each phase of your menstrual cycle. For example, you may only do gentle exercises such as yoga or eat more fermented foods during the first phase of menstruation.

Social media influencers are spruiking cycle syncing as a more natural way for women to manage negative symptoms, such as period pain, and be more in tune with their bodies.

So how does it work? And is it supported by research?

The menstrual cycle

During menstruation, the body sheds the uterus lining to prepare for pregnancy. This usually happens every 28–35 days. But bleeding is only one part of the menstrual cycle. The menstrual cycle can be divided into three main phases:

1. follicular phase, where the body releases a hormone called the follicle-stimulating hormone to help follicles grow in the uterus

2. ovulation, where the ovary releases a mature egg that may or may not be fertilised

3. luteal phase, where the body releases a hormone known as progesterone that thickens the lining of the uterus, in preparation for pregnancy. But if the egg is not fertilised, the uterus will shed its lining and this cycle repeats.

Throughout the menstrual cycle, fluctuating hormone levels can cause symptoms such as fatigue, cramps, bloating, mood swings and changes in appetite.

Read more: Planning a baby? A fertility app won’t necessarily tell you the best time to try

Does ‘cycle syncing’ work?

Advocates of cycle syncing say it helps women manage period symptoms and meet the the body’s changing energy needs during menstruation.

However, specific claims often conflict with each other. For example, some who promote cycle syncing suggest eating fermented foods and fresh vegetables during the follicular phase, while others recommend eating lean proteins and wholegrains. Certain cycle syncing advocates emphasise doing cardio workouts and other high-intensity exercise in the follicular phase. Meanwhile, others say swimming or cycling are better options to manage period symptoms.

However, there is little evidence to support these claims.

Various systematic reviews – which summarise all the available research on a specific question – have found no evidence that doing exercise during certain phases of the menstrual cycle improves muscle development or performance. This is the case with both resistance training which aims to build strength, and aerobic exercise, which increases your heart rate.

It also does not appear to reduce your risk of muscle injuries. Research shows immune function may fluctuate throughout the menstrual cycle, but one systematic review found this variation is unlikely to impact exercise.

Read more: Can exercise reduce period pain? And what kind is best?

However, research suggests female athletes may feel less motivated or confident playing sport in the late luteal phase. They were also more likely to think they performed worse at the start and end of their period. This may be because symptoms such as cramping, back pain and tiredness make exercise seem much harder during menstruation.

But research suggests certain types of exercise, including strength training and relaxation-based exercises, may help relieve period pain.

There’s even less evidence examining the link between nutrition and different phases of the menstrual cycle. One 2024 study suggested women may be hungrier or eat more during their luteal phase, compared to the follicular phase. This may be because during the luteal phase, the body consumes more energy to prepare for a potential pregnancy.

However, one systematic review found no conclusive evidence that changing your diet reduces symptoms such as cramps, bloating and fatigue.

What to do instead

Existing studies looking at the relationship between diet, exercise and different menstrual phases have produced extremely varied results. And there are still many gaps in current research, including what the mechanism behind cycle syncing actually is and what its benefits may be.

So for those who want to manage period symptoms, the best approach is to be patient with yourself and listen to bodily cues. For example, if you slept badly because of night-time cramps, you don’t need to do a high-intensity workout the next morning. Consider going for a walk instead. And if you feel extra hungry near the end of your period – in the luteal phase – it’s fine to eat a little more.

The jury’s out as to whether cycle syncing actually works. But making small lifestyle tweaks could help make your time of the month that bit more manageable.