Eating with your cycle

What genuinely changes

Two hormones do most of the work. Oestrogen rises through the follicular phase and peaks just before ovulation; progesterone rises through the luteal phase and falls away if there is no pregnancy. Both have real metabolic effects, and both are worth understanding before you decide what, if anything, to change.

The reliable ones: resting metabolic rate is modestly higher in the luteal phase, often by a hundred to three hundred calories. Core temperature is higher, which makes heat and humidity harder work. Progesterone is mildly catabolic, which nudges protein needs up. And late-luteal fluid shifts are why the scales move for reasons that have nothing to do with fat.

What the evidence does not support

The elaborate four-phase training and eating protocols sold as cycle syncing run well ahead of the data. Performance research across the cycle is genuinely mixed, the effect sizes are small, and the between-women variation is far larger than the between-phase variation. Most of the confident charts you have seen are extrapolation.

That does not make the cycle irrelevant. It means the useful version is personal: track how you actually feel and perform, and adjust from your own pattern rather than from a diagram.

The version worth doing

Eat a little more in the luteal phase rather than fighting the appetite change, because the extra requirement is real. Push protein slightly higher in that phase. Take salt and fluid seriously around heat and around your period. If your period is heavy, get ferritin measured rather than assuming.

And if training feels harder in the days before your period, that is information, not weakness. Plan the hard sessions where you reliably do them well.

• 01

  Eat with the luteal appetite rather than against it

  Follow the physiology
• 02

  Get ferritin checked if your periods are heavy

  The overlooked one
• 03

  Build the plan from your own tracking, not a diagram

  Personal, not generic