Fasting has numerous health benefits. But: fasting can also upset hormone balance and even lead to infertility.
Fewer cravings, reduced body fat, more energy: Intermittent fasting can have many positive effects.
Can. Because women who fast intermittently also frequently observe hair loss, mood swings, sleep problems, or irregularities in their menstrual cycle.
“If women try to fast but don’t do it properly, it can do them more harm than good,” explains Laura van de Vorst, a nutritionist and hormone expert from Hamburg.
“This is because our metabolic functions are influenced by our hormones.”
The Role of Hormones in Intermittent Fasting
Hormones control our bodies. They control energy metabolism, stress metabolism, and how we feel.
“Hormones can have either a positive or negative influence on your metabolism,” says Laura van de Vorst,” and therefore on other bodily functions.”
When we don’t eat for an extended period of time, as in fasting, the body goes into a kind of survival or protection mode.
To survive this “famine,” the body wants to maintain its weight – and not give up its expensive fat reserves.
In addition, our adrenaline and cortisol levels rise as the starvation phase signals to the body, “There’s no food, your life is in danger!”
The problem with this: as a result, reproductive function takes a back seat – and with it the production of the sex hormones estrogen and progesterone.
Hormone imbalance is possible with interval fasting
When too much energy is needed to produce the stress hormones cortisol and adrenaline, the production of the other hormones is cut back.
This leads to a hormone imbalance. Among other things, this affects our menstrual cycle – and negatively impacts fertility.
In a study with rats, this effect was shown. The female rats fasted intermittently for 12 weeks.
After just two weeks, it was found that their ovaries had shrunk. In addition, the animals suffered more from sleep disturbances than the male rats, who also fasted.
Estrogen and progesterone influence your mood
But fasting doesn’t just affect our fertility. “Estrogen also has an influence on our metabolism, our mood, and in weight loss,” explains Laura van de Vorst.
In addition, estrogen is 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’re a woman, intermittent fasting can destroy the estrogen balance and negatively affect all of these important physiological processes,” Laura says.
Progesterone, like estrogen, is an important pregnancy hormone, but it’s also significant in making us feel happy.
But if our progesterone levels are low and we’re producing more cortisol at the same time, it can lead not only to feelings of anxiety, PMS, and mood swings, but also to water retention, weight gain, sleep problems, or extreme fatigue.
Hormone production in men and women
The hormones that regulate ovulation in women and sperm production in men are regulated in both cases by the so-called hypothalamic-pituitary-gonadal axis.
After the release of the so-called gonadotropin-releasing hormone (GnRH), “follicle-stimulating hormone” (FSH) is released in women, which causes ovulation and estrogen synthesis.
Progesterone is then produced. Estrogen and progesterone are extremely sensitive to when and what we eat.
In men, the GnR hormone triggers the production of testosterone and sperm.
The difference is that this response occurs more constantly in men, but in women, it only occurs at a very specific time within their cycle.
Because the GnRH pulses are precisely timed, small changes can upset hormone balance – which is why women are more sensitive to intermittent fasting than men.
Fasting: What women should watch out for
So for our bodies to function properly, and for us to feel good and be full of energy, it’s important that our hormones are in the right balance. Prolonged periods of fasting can turn the hormone balance upside down.
Should women fast at all then?
Laura’s answer is yes! “You can do intermittent fasting in a way that will improve your hormone health, rather than harm it.”
Done correctly, we can easily bypass the risks and reap all the health benefits of fasting: lower body fat, improved insulin sensitivity, improved inflammatory markers, and more energy.
The hormone expert recommends: These are the rules you should follow
- Do not fast on consecutive days. Instead, fast on Tuesday, Thursday, and Saturday, for example.
- Do not fast for longer than 12 to 13 hours. A fasting period between 7 and 8 p.m., for example, is optimal. A longer fasting window will trigger a stress response
- Don’t exercise too hard on fasting days. Instead of intense workouts like HIIT, long runs, or strength training, focus on yoga or light cardio.
- Do not fast during your period
- Make sure to drink enough water when you fast
- Your diet should be adapted to your hormonal needs and low in inflammatory substances. This means no gluten, no sugar, no dairy products, or red meat.
- Very important: listen to your body. If you don’t feel well during fasting, have headaches, or are irritable, don’t overdo it. Every woman reacts differently to abstaining from food. Be mindful of yourself and take it easy on the days you fast.
Should women avoid intermittent fasting?
Intermittent fasting is not for every woman, though. You should not fast if you
- previously had or had an eating disorder
- are pregnant, breastfeeding, or trying to become pregnant
- have sleep problems
- have low blood pressure, diabetes, blood sugar problems, adrenal insufficiency, or cortisol problems
- are taking medications
- Are underweight
- suffer from amenorrhea (absence of menstruation)