Does Intermittent Fasting Work in Perimenopause?: What the Research Shows

Does Intermittent Fasting Work in Perimenopause?: What the Research Shows

A 12-week study gave 59 women in perimenopause, menopause or post-menopause either exercise alone or exercise plus 16:8 time-restricted eating. Both groups improved on some thinking-speed tests. Adding fasting to exercise did not improve memory or brain health scores more than exercise alone did.

Medical disclaimer: This article summarises published research for informational purposes only. It is not medical advice and is not a substitute for guidance from a qualified health professional. Always consult your doctor before starting any fasting protocol, especially if you have an existing health condition or take medication.

The Short Version

• What they tested: Whether adding 16:8 fasting (eating only in an 8-hour window) to an exercise program helps the brain more than exercise alone.
• Who did it: B. Jóźwiak and colleagues at Poznan University of Physical Education, Poland, published in Frontiers in Public Health in 2025.
• How many people: 59 people, all women, going through perimenopause, menopause, or past it. Exact ages were not stated.
• How long: 12 weeks.
• What happened: Both groups got faster on one thinking test. Fasting on top of exercise added no extra brain benefit.
• Read the study yourself: Frontiers in Public Health 2025 →

What They Wanted to Find Out

Many women notice foggy thinking during perimenopause. Researchers wanted to know if skipping food for part of the day could help the brain, on top of exercise. They tested a popular pattern called 16:8 — eating only within an 8-hour window each day. If you want the fuller research write-up of this exact study, see adding fasting to exercise and brain function in menopause. For how fasting affects weight at this life stage, see does intermittent fasting cause weight loss in menopause.

Who Was in the Study

Who they were: All 59 people were women. They were in perimenopause, menopause, or past menopause. Exact ages and weight details were not stated in the abstract.

What the fasting actually looked like: The fasting group ate all their food inside an 8-hour window each day. They fasted for the other 16 hours. The study did not say exactly what time the window started or ended, or what they could drink while fasting.

What Happened

Both groups got quicker on one thinking test, but fasting added nothing extra on top of exercise.

• Both groups got quicker at a timed sorting test called the Stroop test.
• Only the exercise-only group got better at ignoring distracting words while reading.
• Only the exercise-only group showed more brain-wave activity during rest and during a memory task.
• Neither group changed on the main memory test.
• Neither group showed a change in BDNF or GDNF — two proteins linked to brain cell growth.

What Did Not Change

• Scores on the main memory test stayed the same in both groups.
• BDNF (a protein linked to brain cell growth) did not change in either group.
• GDNF (another brain-growth protein) did not change in either group.
• Muscle mass was not measured in this study, so it cannot say anything about muscle.

What the Researchers Said

The researchers said exercise, not fasting, seemed to be the main driver of brain benefits here. They concluded that adding 16:8 fasting to exercise gave no extra boost to thinking skills in this group of women.

What This Means for You

• If your goal is brain health, this study points to exercise, not fasting, as the main lever. Fasting added nothing extra here.
• This study was done only on women, so it speaks directly to women in perimenopause and beyond — but it says nothing about men.
• It did not test weight loss. For that question, see intermittent fasting and weight loss around menopause.
• It did not measure cortisol or stress hormones. For fasting and stress hormones, see how fasting timing affects cortisol.
• It ran for only 12 weeks, so it cannot say what happens with fasting over a year or more.
• Combining fasting with exercise did not cause harm in this small group, which may reassure some women.

What This Study Could Not Tell Us

• It had only 59 people, split into two fairly small groups.
• It ran for 12 weeks, so longer-term effects are unknown.
• Exact ages, weight, and health conditions of the women were not stated in the abstract.
• It only tested 16:8 fasting combined with exercise, not fasting on its own.
• Funding for the study was not stated in the abstract.

The Study Details

Jóźwiak, B., Kleka, P., & Laudańska-Krzemińska, I. (2025). Effect of exercise alone and in combination with time-restricted eating on cognitive health in menopausal women. Frontiers in Public Health. PMID: 40880914

Common Questions

Does intermittent fasting work in perimenopause?

For brain health, this study found exercise mattered more than fasting. Adding 16:8 fasting to exercise did not improve thinking scores any more than exercise alone over 12 weeks.

Intermittent fasting perimenopause cortisol — does fasting raise stress hormones?

This study did not measure cortisol. Not stated in the abstract. A different study looked at fasting and stress hormone timing — see the link above.

Intermittent fasting perimenopause weight loss — will I lose weight?

This study did not measure weight loss. Not stated in the abstract. For a study that does test weight at this life stage, see the linked article above.

Is intermittent fasting good in perimenopause?

This study found fasting plus exercise was not harmful over 12 weeks in 59 women. It also found no extra brain benefit from adding fasting to exercise.

What is 16:8 intermittent fasting?

It means eating all your food within an 8-hour window each day. You fast for the other 16 hours. In this study, 26 women followed this pattern alongside exercise.

More Research Like This

• Adding fasting to exercise and brain function in menopause
• Time-restricted eating works the same before and after menopause
• Does fasting cause weight loss in menopause?
• Does intermittent fasting help menopause night sweats?
• Fasting plus interval workouts for women over 50
• Intermittent fasting improved fitness in postmenopausal women
• When you eat changes your stress hormones

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