Can You Really Do Intermittent Fasting While Pregnant?

Dieser Artikel basiert auf wissenschaftlichen Studien

Intermittent Fasting While Pregnant | Safety | Risks | Fertility

Since scientists could prove numerous health benefits of intermittent fasting, the interest in the method exploded.

During pregnancy, the female body undergoes constant change.
Therefore you should always speak with your doctor before you change your eating habits substantially.

Even if you are experienced in intermittent fasting, the question arises whether pregnancy is the right time.

What Is Intermittent Fasting?

Intermittent fasting means eating within a certain period and fast the rest of the day.

Although there are types of intermittent fasting, the most popular is fasting during a 16-hour time window.

Hence, with the 16/8 schedule, you only eat 8 hours per day, for example, from noon to 8 PM.

Drinking, however, is allowed around the clock, as long as it is water, black coffee, or tea without any additives.

Health Benefits

In summary, there are two main reasons for intermittent fasting:

  • Weight loss
  • Health benefits

Autophagy induces the lion’s share of the fasting’s health benefits that have made it that popular.

Weight loss, however, is induced by another process called ketosis. In short, it is nothing else than your body tapping into stored fat due to a lack of energy supply.

Remarkably, fat-burning and autophagy require low levels of the storage hormone insulin.

As a result, we get a third substantial benefit of intermittent fasting. It increases insulin sensitivity, thus improving blood-sugar metabolism and fighting metabolic diseases such as type 2 diabetes.

Autophagy and Ketosis

Fasting induces autophagy, a cellular recycling mechanism that replaces broken cell parts with new ones and detoxifies the body.

Besides preventing cancer, diabetes, liver, or autoimmune diseases, these fasting cleanses can also slow aging (Levine et al. 20171; Gelino et al. 20122).

On the other hand, Ketosis means that the body has emptied its carbohydrate stores and burns fat for energy production.

Since the body delivers the energy in the form of ketone bodies through the bloodstream, this state of fat burning is called ketosis.

This natural mechanism has ensured the survival of our species. Thus, the body can tap into body fat during food shortages, such as once in winter or today when fasting.

Moreover, the body is fasting between dinner and waking up for our first meal. Also, this applies to pregnant women.

Accordingly, ketosis during pregnancy is entirely normal and enhanced by it.

For this reason, the ketone level in the blood of healthy pregnant women after a night’s fasting is about three times higher than that of women who are not pregnant (Felig et al. 19703).

With this in mind, two living beings need additional energy, which the body can supply through ketosis.

So we summarize that intermittent fasting helps the body to achieve the following effects:

  • Weight loss through fat burning
  • Recycling of cells instead of growth

Can You Do Intermittent Fasting While Pregnant?

After many women ask themselves whether it is safe to practice intermittent fasting during pregnancy, there is a general answer.

Always talk to your doctor before you make any significant changes to your diet.

If we consider that intermittent fasting promotes weight loss and limits growth, a controversy about pregnancy arises.

Pregnancy, on the other hand, has different goals than fasting:

  • Weight gain of the child
  • Growth in a short time

Since the goals could hardly be more opposite, it surprises little that nobody can recommend intermittent fasting while a woman is pregnant.

Beyond that, too few studies could give well-founded recommendations regarding whether intermittent fasting has positive or negative effects on pregnancy.

Furthermore, no studies are targeting intermittent fasting during the entire pregnancy.

Aggravating is that studies about fasting while pregnant are limited to Ramadan.

During this religious type of intermittent fasting, one does not eat from sunrise to sunset. In contrast to intermittent fasting for health benefits, you eat right before and after sleep.

With this in mind, the significance of these studies for intermittent fasting decreases.

However, these studies on Ramadan fasting while pregnant suggest that the fast does not influence the following characteristics (Glazier et al. 20184; Petherick et al. 20145):

  • Birth Weight
  • Premature births

Although these investigations do not suggest any adverse effects of fasting on pregnancy, the researchers agree that there is still far too little data to conclude.

Moreover, we must note that the Islamic fasting custom excludes pregnant women. Nevertheless, many of them do fast.

However, it is interesting that a current study could determine the reduced risk of gestational diabetes and obesity by fasting in the second trimester (Safari et al. 20196).

Intermittent fasting is not ideal in pregnancy

Is Intermittent Fasting Safe During Pregnancy?

Although we struggle with these diseases of too much growth and proteins, there are still phases in life where growth is the main focus. And pregnancy is an essential one of them.

Accordingly, two lives require more energy and protein than just one.

Increased ketone levels in pregnant women stress this fact. The body mobilizes energy from fat reserves if insufficient energy is available to ensure a child’s healthy growth (Felig et al. 19707).

Therefore, pregnancy is a period that has particular priorities:

  • Nutrient supply for healthy body development
  • Exceptional growth and weight gain in a short time
  • Development of maternal fat reserves for breastfeeding

Likewise, the purpose of breast milk in all mammals stresses out these growth and weight gain goals.

Against this background, dramatically changing eating habits can lead to nutrient deficiencies.

Moreover, fasting can change the hormone balance. For example, the release of norepinephrine is increased, which is not ideal during rest (Zauner et al. 20008).

On top of that, human bodies are individual. Thus fasting can have different effects. Therefore nothing can replace the personal exchange with a doctor you trust.

Therefore apparent alternatives arise in pregnancy:

  • Working out an individual plan for healthy weight gain with the help of medical professionals
  • Listening to your body, as it is always striving for the nutrients it needs (except the addictive effect of sugar)

Possible Risks

During pregnancy, you already have enough on your mind. Therefore a strict fasting protocol would probably only increase the stress.

If you do not take care of yourself, you risk not providing your child with the high-quality food it needs.

Above all, long-term effects are largely unclear due to a lack of appropriate research.

While some Ramadan fasting studies claim to affect fetal respiration, others say there is no link between fasting and child health (Mirghani et al. 20049; Petherick et al. 201410).

With this in mind, we must conclude that rigorous intermittent fasting during pregnancy is risky.

Ultimately, adequate nutrient supply for mother and child has priority.

For example, iron deficiency is a problem in pregnant women, as the iron requirement increases exponentially due to the fetus. Accordingly, potential anemia threatens the child and the mother (Garzon et al. 202011).

Adequate intake of minerals from natural food can minimize such risks. In iron deficiency, consumption of beef liver (*) or beetroot (*) can prevent iron deficiency.

Fasting and Fertility

In our context, it’s interesting that restoring the natural balance between feasting and fasting can benefit fertility.

Accordingly, due to intermittent fasting, researchers observed increased luteinizing hormone that promotes ovulation.

Additionally, the weight loss and mental health resulting from fasting contribute to fertility (Nair et al. 201612).

PCOS is the most common metabolic disorder in women. Thereby cysts on the ovaries develop induced by a hormonal imbalance.

Like type 2 diabetes, polycystic ovarian syndrome is characterized by obesity, high blood pressure, and insulin resistance. More precisely, it is even caused by strong insulin resistance, which increases the risk of diabetes in young women (Ali 201513).

Intermittent Fasting Before Pregnancy

Since it can increase fertility, intermittent fasting seems reasonably practicable, as no pregnancy is still suspected.

You might reap benefits while pregnant if you do intermittent fasting before pregnancy to increase a future mother’s health.

When we look at the health benefits of intermittent fasting, that can make sense:

  • Increased insulin sensitivity
  • Reduced inflammation
  • Improved metabolism
  • Increased fat burning
  • Improved gut health

However, when getting pregnant, even experienced fasting enthusiasts should individually discuss the topic with a professional. She might even allow you to continue mild fasting due to your condition.

Keto and Intermittent Fasting

That you cannot continue fasting precisely the same way does not mean that you have to neglect your diet during pregnancy.

That’s why you can always focus on healthy fats and avoid refined carbohydrates during your meals.

For example, this means reducing sweets, bread, and other bakery and instead including grass-fed butter, virgin coconut oil, or avocados into your diet.

Simultaneously, this mild keto-style fat fasting can keep you fuller for longer and prevent gestational diabetes without having to forego adequate nutritional intake.

Nevertheless, you need not be ashamed of eating more during pregnancy. Excessing 200-400 calories daily is relatively standard in a healthy pregnancy.

However, even during pregnancy, you should prefer natural foods and gratefully reject processed foods from colorful packaging.

You may feel lethargic and dirty, especially in the first few months. Although this may sound controversial, exercise can improve the condition.

Furthermore, adequate physical exercise improves insulin sensitivity and reduces the risk of gestational diabetes (Nasiri-Amiri et al. 201914).

Exercise can even reduce the risk of cesarean section delivery (Owe et al. 201615).

If you have been exercising regularly before pregnancy, this is ideal. Nevertheless, even in this case, you must ask your doctor if you need to change your exercise routine.

If you want to get some exercise in your life right now, walking, cycling, or swimming in moderate units (up to 45 minutes) might be suitable, provided your doctor approves this.

Intermittent Fasting Post Pregnancy

That you should not overdo intermittent fasting while pregnant does not mean that you cannot find back into your fasting plan afterward.

However, after the strains of birth, there is no question that you cannot immediately go from 0 to 100 again. And if you are breastfeeding, you must discuss this intention with your doctor.

Nevertheless, intermittent fasting post-pregnancy can help you to regain first-class health.

As studies have shown, intermittent fasting helps to (Varady et al. 200916):

  • Burn fat more effectively
  • Lose weight more easily
  • Improve blood lipids
  • Fight hypertension

Furthermore, women who practiced intermittent fasting could witness mental benefits. As a result, these women experienced more success, pride, and control (Watkins et al. 201617).


Pregnancy is not an excellent time for experiments. You should not start while pregnant if you haven’t done intermittent fasting before.

However, pregnancy does not last forever.

If you want to try intermittent fasting, the best time is after delivery. If your doctor gives the green light, you can lose weight more efficiently and improve your health.

Nevertheless, the female body is not a machine. Whether you feel physically or mentally overwhelmed before, after, or during pregnancy, don’t hesitate to seek professional help.

Intermittent Fasting 16/8 for Women Book

Frequently Asked Questions (FAQ)

Can fasting affect early pregnancy?

Until now, there is insufficient research to conclude whether fasting affects early pregnancy safely. Hence, speak to your doctor before considering fasting.

How long can you fast while pregnant?

It would be best to focus on providing your child with adequate nutrients. Therefore, speak to your doctor before considering fasting during pregnancy.

Can a pregnant woman keep Roza?

The Islamic custom allows pregnant women to quit fasting during Ramadan.



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Mag. Stephan Lederer, MSc.

Mag. Stephan Lederer, MSc. is an author and blogger from Austria who writes in-depth content about health and nutrition. His book series on Interval Fasting landed #1 on the bestseller list in the German Amazon marketplace in 15 categories.

Stephan is a true man of science, having earned multiple diplomas and master's degrees in various fields. He has made it his mission to bridge the gap between conventional wisdom and scientific knowledge. He precisely reviews the content and sources of this blog for currency and accuracy.

Click on the links above to visit his author and about me pages.

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