Cycle syncing: an evidence check

Cycle syncing is the idea that you should change your workouts, food, work and social life to match each phase. It is all over social media. So does it hold water? Short answer: your cycle can affect how you feel, but the strict rules do not have good evidence behind them.

What the research shows

A 2020 systematic review and meta-analysis pooled many studies on exercise performance across the cycle. It found performance might be trivially lower in the early follicular phase (around your period), but the evidence was rated low quality and results varied a lot between people. The authors recommended a personalised approach over general rules.

A 2023 review looked specifically at strength training and found no clear influence of cycle phase on strength or muscle gains. The authors suggested tailoring plans to the individual because the evidence is not strong enough to design programmes around phases.

For phase-based diets (for example, eating certain seeds in certain weeks), there is no good-quality evidence that they change hormone levels or fix symptoms. The NHS also says there is not much evidence that supplements such as vitamin B6, calcium or magnesium help with PMS.

What is genuinely useful

• Noticing your own patterns, such as low energy before your period or a mood lift mid-cycle.
• Planning a bit of extra rest or comfort when you know cramps tend to hit.
• Keeping meals regular and nourishing, which the NHS suggests for PMS (smaller meals every 2 to 3 hours may suit some people).
• Regular exercise, which the NHS lists as helpful for PMS, whatever the phase.
• Not forcing yourself into rules that do not fit how you actually feel.