Intermittent fasting for women: How to do it safely with your hormones in mind

Intermittent fasting, or IF, is one of the most talked about health trends. It promises more energy, easier weight management, sharper focus and even anti-ageing effects. But there’s one important detail that’s often overlooked. Most research has been done on men. For women, fasting can look and feel very different because of hormonal fluctuations. What works for men doesn’t always work the same way for us. Here’s what you need to know about intermittent fasting for women, how it affects your hormones, and how to approach it safely and supportively.

Table of contents

1. What is intermittent fasting?

2. Why fasting affects women differently

3. How to do hormone-friendly intermittent fasting

4. When to fast, and when not to, in your cycle

5. Who should avoid fasting

6. The takeaway

What is intermittent fasting?

Intermittent fasting is an eating pattern where you alternate between periods of eating and not eating. It doesn’t restrict specific foods, but rather focuses on when you eat. The most common approaches include:

• 16:8 16 hours of fasting and an 8-hour eating window

• 14:10 14 hours of fasting and a 10-hour eating window

• 5:2 eating normally for five days and reducing calories on two

• OMAD (One Meal A Day) eating all your calories in one meal

You don’t need to start with an extreme version. Even a simple 12-hour overnight break, such as 8 p.m. to 8 a.m., can already offer benefits.

Why fasting affects women differently

From an evolutionary perspective, survival takes priority over reproduction. Fasting can signal stress to the body (no food equals stress), which makes your body produce more cortisol, the stress hormone, while reducing oestrogen and progesterone. Women who still have a menstrual cycle may notice irregular periods, stronger PMS, anxiety, poor sleep or a slower thyroid when fasting too aggressively.

This doesn’t mean women shouldn’t fast. It means we need to approach it with more nuance, flexibility and awareness of our hormones.

How to do hormone-friendly intermittent fasting

1. Start gently with shorter fasting windows: Jumping straight into a 16:8 rhythm can be too much. Begin with 12 hours, for example 8 p.m. to 8 a.m., and see how you feel. You can slowly extend if your body responds well.

2. Prefer eating earlier in the day: Many women feel better when they eat earlier because cortisol is naturally higher in the morning. An eating window from 8 a.m. to 4 p.m. can be more supportive than skipping breakfast.

3. Align fasting with your cycle:

• Follicular phase (after menstruation until ovulation): your body can handle more stress. This is the best time for longer fasting windows of 14 to 16 hours.

• Luteal phase (after ovulation until menstruation): your body is more sensitive to stress. Opt for shorter fasting windows or skip fasting altogether.

4. Always check in with your body: If you’re tired, under pressure or recovering from illness, fasting isn’t a good idea. It should feel supportive, not depleting.

Intermittent fasting and menopause

After menopause, things change. Hormonal fluctuations become smaller, making fasting often easier. Research suggests that intermittent fasting can support blood sugar balance, energy levels and weight management, which often become more challenging after menopause. Still, this life stage can bring its own symptoms, such as sleep problems, hot flashes or mood changes. Starting gently with 12 to 14 hours of fasting usually works best. Combine it with nutrient-rich meals, strength training and stress care for lasting results.

Who can benefit from intermittent fasting?

• After menopause, when monthly hormonal shifts are minimal

• When using hormonal contraception, as natural fluctuations are reduced

• With PCOS or insulin resistance, to stabilise blood sugar levels

• When you are healthy, hormonally balanced and curious to try it

Who should avoid intermittent fasting?

• During pregnancy or breastfeeding

• With irregular or absent periods

• When recovering from burnout or illness

• With thyroid or adrenal issues

• During periods of high stress or poor sleep

• When struggling with fertility issues

• With a history of disordered eating

Important: fasting is a tool, not an obligation. If it doesn’t feel good, it’s not right for you.

To sum up

Intermittent fasting can offer benefits for women, but only when it’s adapted to your body, your hormones and your lifestyle. It works best when you do it gently, flexibly and with self-awareness.

Key takeaways

• Intermittent fasting affects women differently because of hormones.

• Start slowly with a 12-hour fast and expand gradually if it feels good.

• Match fasting with your cycle. Longer during the follicular phase, shorter or none during the luteal phase.

• Fasting isn’t for everyone. Avoid it during pregnancy, breastfeeding or fertility issues.

• The best way to fast is the one that feels supportive, not stressful.

References:

Garg, R., Chetan, R., Jyothi, G. S., Agrawal, P., & Gupta, P. (2025). Intermittent Fasting and Weight Management at Menopause. Journal of Mid-Life Health, 16(1), 14–18. https://doi.org/10.4103/jmh.jmh_227_24

Jóźwiak, B., Domin, R., Krzywicka, M., & Laudańska-Krzemińska, I. (2024). Effect of exercise alone and in combination with time-restricted eating on cardiometabolic health in menopausal women. Journal of Translational Medicine, 22(1). https://doi.org/10.1186/s12967-024-05738-y

Mao, L., Liu, A., & Zhang, X. (2024). Effects of Intermittent Fasting on Female Reproductive Function: A Review of Animal and Human Studies. Current Nutrition Reports. https://doi.org/10.1007/s13668-024-00569-1

Nair, P. M. K., & Khawale, P. G. (2016). Role of therapeutic fasting in women’s health: An overview. Journal of Mid-Life Health, 7(2), 61. https://doi.org/10.4103/0976-7800.185325

Tuswandi Ahmad Waly, & Bayu Setyo Nugroho. (2025). The Analysis Study  Effect of Intermittent Fasting on Female Reproductive Hormones and Menstrual Cycle: A Comprehensive Systematic Review. The International Journal of Medical Science and Health Research, 9(5), 29–46. https://doi.org/10.70070/mrwarz94