Fasting can affect menstruation

Intermittent fasting for women: You should know these differences

Less cravings, reduced body fat, more energy: Intermittent fasting can have many positive effects.

Can. Women who fast intermittently also often observe hair loss, mood swings, sleep problems, or irregularities in their cycle. And that only when you simply allow more time to pass between dinner and breakfast?

Yes. Because fasting is not the same for men and women.

"If women try to fast but don't do it properly, it can do them more harm than good," explains Laura van de Vorst, nutritionist and hormone expert from Hamburg. "This is because our metabolic functions are influenced by our hormones."

Intermittent fasting and the role of hormones

Hormones control our body. They control the energy metabolism, the stress metabolism and how we feel.

"Hormones can either have a positive or negative influence on your metabolism," says Laura van de Vorst, "and thus also on other body functions."

If, as with fasting, we do not eat for a long period of time, the body goes into a kind of survival or protection mode. In order to survive this "famine", the body wants to maintain its weight - and not give up its expensive fat reserves.

In addition, our adrenaline and cortistol levels rise, as the hunger phase signals to the body: "There is no food, your life is in danger!"

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The problem with this is that the reproductive function takes a back seat - and with it the formation of the sex hormones estrogen and progesterone. If too much energy is used for the production of the stress hormones cortisol and adrenaline, the production of the other hormones is reduced.

This leads to a hormone imbalance. Among other things, this affects our menstrual cycle - and negatively affects fertility.

This effect was shown in a study with rats. The female rats fasted intermittently for 12 weeks. After just two weeks, it was found that her ovaries had shrunk. In addition, the animals suffered more from sleep disorders than the male rats, which also fasted.

The sex hormones estrogen and progesterone

But not only our fertility is affected by fasting. “Estrogen also has an impact on our metabolism, mood and weight loss,” explains Laura van de Vorst.

Estrogen is also involved in the development of anxiety and stress and is important for the health of our skin and hair, bone density, muscle tone and our cognitive functions.

"If you are a woman, intermittent fasting can destroy the estrogen balance and negatively affect all of these important physiological processes," says Laura.

Progesterone, like estrogen, is an important pregnancy hormone, but it is also important for making us feel happy.

However, if our progesterone levels are low and we produce more cortisol at the same time, this can not only lead to feelings of anxiety, PMS and mood swings, but also to water retention, weight gain, sleep problems or extreme fatigue.

Hormone Production: The Difference Between Women and Men

The hormones that regulate ovulation in women and the production of sperm in men are regulated in both cases via the so-called hypothalamic-pituitary-gonadal axis.

After the release of the so-called gonadotropin-releasing hormone (GnRH), the “follicle-stimulating hormone” (FSH) is released in women, which causes ovulation and the synthesis of estrogen. Progesterone is then produced. Estrogen and progesterone are extremely sensitive to what and when we eat.

In men, the GnR hormone triggers the production of testosterone and sperm.

The difference is that this response is more constant in men, but in women only at a specific point in their cycle. Since the GnRH impulses are precisely timed, small changes can upset the hormonal balance - this is why women are more sensitive to intermittent fasting than men.

This is how women fast properly

So in order for our bodies to function properly, to feel good and to be energetic, it is important that our hormones are in the right balance. Longer fasts can turn the hormonal balance upside down.

Should women then fast at all?

Laura's answer is: yes! "You can intermittent fasting so that it improves your hormonal health rather than harming it."

If done correctly, we can easily bypass the risks and benefit from all the health benefits of fasting: less body fat, improved insulin sensitivity, improved inflammation markers and more energy.

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The hormone expert recommends these simple rules for women:

  • Do not fast on consecutive days. Instead, fast for example on Tuesday, Thursday and Saturday.
  • Do not fast for more than 12 to 13 hours. A fasting phase between 7 p.m. and 8 a.m., for example, is ideal. With a longer fasting window, a stress reaction is triggered
  • Don't exercise too hard on the fasting days. Instead of intensive training such as HIIT, long runs or strength training, you should focus on yoga or light cardio training
  • Don't fast on your period
  • Make sure to drink enough water when you fast
  • Your diet should be tailored to your hormonal needs and contain few inflammatory substances. That means: no gluten, no sugar, no dairy products or red meat
  • Very important: Listen to your body If you are unwell fasting, have a headache, or are irritable, don't overdo it. Every woman reacts differently to not eating. Be mindful of yourself and take it easy on the days you fast.

Then women should not fast intermittently

Intermittent fasting, however, is not suitable for every woman. You shouldn't fast if you

  • have previously had or have an eating disorder
  • are pregnant, breastfeeding, or trying to get pregnant
  • Have trouble sleeping
  • have low blood pressure, diabetes, blood sugar problems, adrenal fatigue or cortisol problems
  • Take medication
  • are underweight
  • suffer from amenorrhea (lack of menstruation)

Our expert

Laura van de Vorst is a nutritionist, hormone expert and founder of For years she herself suffered from autoimmune problems, extreme fatigue, digestive and cycle problems caused by hormonal imbalances.

In 2014 she founded the coaching program healthcoachFX with the aim of freeing women all over the world from hormonal problems through nutrition and naturopathy. Laura van de Vorst offers holistic hormone reset programs and video courses - based on an individual diet, exercise and mindfulness.

Kumar S., Kaur G. (2013): Intermittent fasting dietary restriction regimen negatively influences reproduction in young rats: a study of hypothalamo-hypophysial-gonadal axis, PLoS One. 2013; 8 (1): e52416. doi
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