Fasting During Pregnancy: What You Need to Know

Pregnancy is a time of significant physical and emotional change. As you prepare for the arrival of your baby, your body works hard to support new life. During this time, many women consider making adjustments to their diet and lifestyle, including trying fasting. Whether it’s for health reasons, habit, or personal discipline, it’s important to understand how fasting might affect both you and your baby.

This article will explore what fasting does to the body during pregnancy, the potential risks and considerations, and how to approach it safely if you decide to proceed.

What Is Fasting?

Fasting typically involves going without food for a set period, and in some cases, without water as well. Intermittent fasting, time-restricted eating, and extended fasting are some of the common approaches. People fast for a variety of reasons including weight management, detoxification, and personal wellness.

During fasting, the body shifts from using glucose for energy to using fat stores. This change can result in lower blood sugar levels and the production of ketones, which may be concerning during pregnancy, particularly in large amounts.

Is It Safe to Fast While Pregnant?

There is no single answer to this question, as every pregnancy is different. The safety of fasting during pregnancy depends on several key factors:

Trimester

In the early stages of pregnancy, women often experience nausea, tiredness, and a greater need for hydration and nutrients. Fasting during this time can make those symptoms worse and may lead to dizziness, fainting, or difficulty keeping food down.

In the second trimester, many women feel more stable and energetic. However, even during this more comfortable phase, it's vital to ensure consistent nutrient intake.

In the third trimester, your baby’s growth accelerates and your nutritional needs are higher. Fasting at this stage could lead to reduced energy, dehydration, and slowed foetal growth if not managed carefully.

Health Conditions

If you have any medical conditions, fasting may carry additional risks. Women with gestational diabetes, high or low blood pressure, anaemia, or low body weight should avoid fasting unless their doctor specifically approves it. Dehydration and unstable blood sugar levels can be harmful to both mother and baby.

Duration and Type of Fast

Short periods of fasting with hydration and careful planning may be manageable for some women. However, extended periods without food or water are generally not advised during pregnancy. Skipping meals or following restrictive routines can lead to metabolic imbalances and affect the baby’s development.

What Do Healthcare Professionals Recommend?

Midwives, doctors, and fertility nutritionists generally advise caution regarding fasting during pregnancy. Fertility nutritionist Isabelle Obert commented:

“As blood sugar levels tend to be more disordered in pregnancy, I find that eating little and often tends to work best to support energy levels and potentially keep nausea at bay.”

This guidance reflects a wider consensus: maintaining steady nutrition throughout the day supports both maternal and foetal health.

If You Choose to Fast

If, after consulting your healthcare provider, you decide to try a form of light fasting, here are a few important tips to follow:

Stay Hydrated: Drink plenty of water if your fast allows it. Hydration is essential during pregnancy.

Focus on Nutrient-Dense Foods: Plan meals rich in iron, protein, healthy fats, calcium, and fibre.

Eat Regularly When Not Fasting: Even if you attempt a form of time-restricted eating, aim to eat frequently enough to meet your energy and nutritional needs.
As the nutritionist advises:

“Protein requirements rise during pregnancy, so it is important to eat regularly and include protein with each meal/snack in order to support blood sugar levels and to distribute protein throughout the day.”
“It would not be a good idea to eat huge amounts of proteins in only a couple of sittings.” - Isabelle Obert

Rest and Monitor: Avoid strenuous activity, get plenty of rest, and watch your energy levels. If you feel light-headed, weak, or notice changes in your baby’s movements, stop fasting and seek medical advice.

Keep Medical Appointments: Regular check-ins with your midwife or GP will help ensure you and your baby remain healthy.

The Importance of Listening to Your Body

Pregnancy is not the time to take unnecessary risks with your health. If fasting doesn’t feel right or your body is showing signs of stress, it’s important to stop and prioritise nourishment and rest.
Your body is working constantly to support your baby’s development and this is a time to care for yourself with compassion and attention.

Fasting during pregnancy is a personal decision that should always be made with medical guidance. While some women may manage very light fasting safely, others may need to avoid it completely. Your health and your baby’s development come first.

If you are considering fasting while pregnant, speak to your midwife, GP, or a qualified nutritionist to make a plan that supports both of you safely and effectively.