Is Intermittent Fasting Safe During Pregnancy? An RDN Discusses Prenatal Health and Time-Restricted Eating

Though intermittent fasting (IF) is the latest health trend, it has been part of many people’s cultural and religious practices for thousands of years.

What is IF?

Intermittent fasting is a dietary strategy that alternates fasting and eating periods. Methods include the 5:2 diet (5 normal days, 2 non-consecutive, low-calorie days), alternate-day fasting (alternating normal and 500-calorie days), and time-restricted eating (e.g., 16:8, with an 8-hour eating window). Research shows benefits like improved insulin sensitivity, reduced inflammation, and decreased risk of diabetes and heart disease. In 2016, Yoshinori Osumi won a Nobel Prize for his work on intermittent fasting and cell autophagy.

Now IF has become the go-to-trend for weight loss. But what does this mean for pregnancy?


Can a pregnant woman do time-restricted eating?

Intermittent fasting is generally not recommended during pregnancy. Whether you want to engage in IF for religious reasons or health reasons, we recommend you reconsider.

Pregnancy is a critical period where both the mother and the developing baby require a consistent and adequate supply of nutrients and energy for proper growth and development. Restricting food intake or following fasting schedules can potentially lead to nutrient deficiencies and may not provide the necessary nutrition for a healthy pregnancy.

Here are some specific reasons as to why pregnant women should not practice IF:


  • Nutrient Deficiency: Intermittent fasting can restrict the intake of essential nutrients. Developing babies need a steady flow of nutrients and fasting can interrupt that and be harmful.
  • Energy Needs: Pregnant women require a steady and adequate supply of energy to support the growing baby, and fasting can lead to insufficient calorie intake.
  • Risk of Hypoglycemia: Fasting can cause low blood sugar levels (hypoglycemia), which can be harmful to both the mother and the baby.
  • Impact on Fetal Growth: Insufficient nutrition during pregnancy can potentially hinder fetal growth and development.
  • Hormonal Changes: Fasting may disrupt hormonal balance, which is important for a healthy pregnancy.
  • Dehydration: Extended fasting periods can lead to dehydration, which can be especially risky during pregnancy.
  • Increased Stress: Intermittent fasting can increase stress on the body, and stress is generally discouraged during pregnancy.
  • Risk of Dizziness and Weakness: Fasting can cause dizziness, weakness, and fatigue, which can be dangerous during pregnancy, as it may lead to falls or accidents.
  • Potential for Nutrient Transfer: If a pregnant woman is fasting, there may be a risk of the body diverting nutrients away from the baby to sustain the mother.


Many women are concerned with managing weight gain during pregnancy. IF is not the answer. Every pregnancy is unique, and what works for one person may not work for another. It’s crucial to prioritize a balanced and consistent diet for the health of both the mother and the baby. Consult with a prenatal dietitian to help you reduce the risk of complications during pregnancy and labor. Individualized dietary interventions can help prevent or manage preeclampsia, gestational diabetes, morning sickness, acid reflux, and more.