Does cycle-syncing actually work? Here’s what the research shows

Should your eating and exercise routine change during the phases of your menstrual cycle, in what’s known as cycle syncing? According to a new meta analysis, no.  

“There’s no evidence that a woman’s response to diet and exercise changes during different phases of her menstrual cycle,” the authors wrote.

Some experts say cycle syncing can ease symptoms before and during a period, but a new study says there’s not much evidence that shifting habits during your period matters much. 

“Many women are following advice and planning exercises and practices based on some ostensible benefit of menstrual cycle phase-based exercise. We saw no evidence that such practice is science-based,” said senior researcher Stuart Phillips, PhD, a professor of kinesiology at McMaster University in Hamilton, Ontario, Canada.

The findings were published in the Journal of Applied Physiology. It was a meta-analysis of 55 existing studies including 928 participants.

Dr. Phillips noted that there’s no such thing as a “standard” menstrual cycle lasting 28 days and ovulation consistently happening on day 14. Instead, hormones fluctuate sometimes unpredictably, which can make tying routines to your cycle phases difficult.

“Hormone levels can vary substantially. Not just between two women, but within one woman from one cycle to the next,” co-lead researcher Mai Wageh, a doctoral candidate in McMaster’s department of kinesiology, said in a statement.

The researchers evaluated physiological changes and hormone levels that might occur during the different phases of the menstrual cycle and measured it against exercise. The team wanted to better understand how the menstrual cycle impacts human physiology. But they didn’t come up with much. In fact, they didn’t note changes when women consumed more or less fat or carbohydrates. There weren’t standard changes of muscle growth or blood vessel function during the phases of a woman’s period, either. 

“Although there are some [menstrual cycle]-based effects on various physiological outcomes, we found these differences relatively subtle and difficult to attribute to specific hormones, as estrogen and progesterone fluctuate rather than operating in a complete on/off pattern as observed in cellular or preclinical models often used to substantiate human data,” researchers wrote. “A broad review reveals that the differences between the follicular and luteal phases and between [oral contraceptive] active and placebo phases are not associated with marked differences in exercise performance and appear unlikely to influence muscular hypertrophy in response to resistance exercise training.”

Does cycle syncing work? Researchers aren’t convinced. But if it works for you, go for it, the researchers said. (We agree!) There’s plenty of anecdotal evidence supporting cycle syncing, which involves listening to your body and what it needs during different phases of your menstrual cycle. Just know that there may be lots of variation month to month, and following a set program may need some personal adjustments. 

“Women can feel better or worse, and some are even incapacitated during various phases of their cycle,” Wageh said. “You need an individualized approach to training.  Track your cycle and your symptoms in each phase and adjust your exercise plan accordingly. There is no one-size-fits-all approach.”

The scientists state they still want to know more about menstruating people’s cycles, especially given the fact that women are often under-represented in clinical research, which is the basis behind a new White House initiative steered by Jill Biden. “Considering the menstrual cycle [MC] requires understanding the MC phase, studying males is ‘less work,’” the study authors write, highlighting an implicit belief that could be behind sex-based exclusionary bias in exercise research, specifically.