Can I Fast While Pregnant?

Pregnant woman cutting vegetables

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Intermittent fasting has recently seen an uptick in popularity as it is associated with various health benefits, some backed by research and many not, like reducing inflammation and promoting weight loss. Intermittent fasting is essentially when a person times their meals so that they have phases of voluntary fasting and non-fasting throughout a designated time period.

Because much of the hype around intermittent fasting is wrapped up in diet culture, many people have tried it. It it wouldn’t be unusual for someone who is newly pregnant to want to continue a practice that is commonly viewed as healthful. However, now that you’re expecting, it’s one more thing to add to the, “Hey, is this okay?” list you’ve been keeping.

The short answer: No, it isn’t a good idea to fast while pregnant.

“During pregnancy, energy and nutrient needs are higher, and a pretty constant stream of both of these are needed to keep your baby thriving all while helping you be energized and healthy,” says Ryann Kipping, RDN, founder of The Prenatal Nutrition Library app. “If you’re fasting, it is more likely that you won't be able to meet your calorie or protein needs, and therefore, you won't be able to meet your nutrient needs.”

Fasting During Pregnancy

As opposed to a diet that restricts calories, intermittent fasting basically bundles all of the calories you consume in one day into a designated time period. For example, the popular 16/8 method is when someone fasts for 16 hours and allows 8 hours in the day for eating, like noon to 8 p.m. After 8 p.m., food consumption is considered off-limits until the following day at noon. With fewer hours in the day to eat, it’s more likely you’ll consume fewer calories, even without a rule about counting or restricting calories.

Despite its popularity, the scientific studies focused on fasting are scarce and results are mixed and ongoing.. The general consensus is intermittent fasting needs further research to confirm any benefits.

“There is no data on intermittent fasting during pregnancy, so at this time, it is not considered safe,” says Kipping. “The fasting time between dinner and breakfast is, of course, okay, but ultimately if you are hungry you should eat. When suffering through morning sickness, typically in the first trimester, there may be unintentional periods of fasting which are typically not problematic; however, if [nutrient deficiencies and/or dehydration] occur it can quickly become an issue.”

Every pregnancy is different. Be sure to consult with a healthcare provider about your circumstances if you have any questions about fasting while pregnant.

Is It Safe For Baby?

Fasting while pregnant is not safe for your baby. In a study of people who fasted during Ramadan during the second trimester of their pregnancy, researchers concluded that fasting was linked to preterm birth.

Preterm birth is also often associated with conditions like difficulty breathing, low blood sugar, intestinal inflammation, jaundice, and anemia, just to name a few of the potential complications.

Why You Should Not Fast While Pregnant

Fasting isn’t recommended during pregnancy. Not only can it lower blood sugar to unhealthy levels, but, as previously mentioned, one study suggested it may be associated with preterm birth. It also increases the risk of not getting enough food each day, which can lead to nutrient deficiencies as well as overall energy deficiencies.

“You would never want to deprive your baby of nutrition for 18 hours a day when they are out in the world,” says Joey Adashek, MD, a Las Vegas-based perinatologist specializing in high-risk pregnancy. “If you have a baby, would you ever decide to only feed him or her six hours a day? Of course not. This is the same reason that fasting should not be done during pregnancy.”

Risks of Fasting While Pregnant

These are some potential risks associated with fasting while pregnant.

Potential for Poor Fetal Growth

Pregnant parents are advised not to restrict food during pregnancy to encourage optimal fetal health.

“When the pregnant woman does not consume enough calories, the body attempts to break down fats, increasing ketonuria and ketonemia which are ketones in the urine and blood," says Dr. Adashek. If the nutrient intake of the parent is inadequate, their health and the baby's may suffer. For instance, if the parent does not ingest enough calcium, it could interfere with the development of a healthy skeletal structure.

When Can I Resume Fasting?

If you are breastfeeding, it is recommended to wait until after you've weaned to resume fasting. This is because it's suggested that breastfeeding parents do not restrict.In many cases, a nursing parent will require more energy intake than they did while they were pregnant.

It's also suggested to refrain from fasting immediately after giving birth, as the body needs time to recover from the demands of pregnancy, which requires food and nutrients. Anyone interested in returning to fasting postpartum should seek advice from a medical professional to address concerns and potential complications as well as explore whether it is the right choice for them.

Speaking with a healthcare provider who practices within the 'health at every size" framework can be very helpful to gather factual, science-based advised that isn not intertwined with diet culture.

Pregnancy Safe Alternatives

While fasting is not safe during pregnancy, this can be a good time to explore your relationship with food and your body. It can be a time to think about what you want your relationship with food and eating to be and examine what truly makes you feel best.

Pregnancy is also a time where a past eating disorder or disordered eating thoughts may come back into the picture. If this is the case, seek help from a mental health professional and/or a registered dietitian who works with people with eating disorders or disordered eating.

Satisfy Your Appetite With Nutrient-Rich Foods

Although you may not need to "eat for two" in the often cartoonish way pregnancy is portrayed on television, Kipping says pregnancy is a time when it is ideal to practice eating intuitively. That means tuning into what your body needs and really listening to those signals.

"If you wake up in the middle of the night very hungry, it is in your and your baby's best interest to eat something," she advises. "If you are still hungry after eating a full meal, it is okay to eat more because this is what your body is telling you it needs."

Eat Mindfully

If you were practicing intermittent fasting before you became pregnant, you were mindfully scheduling your meals and snacks within a certain time frame. Apply that same sense of forethought when choosing what kinds of foods to consume throughout the day. A healthy, balanced diet abundant in vitamin-packed fare, like fruits and vegetables, will provide you with the building blocks needed to feel your best.

A Word From Verywell

Fasting isn't recommended during pregnancy. Although this may not be the answer you were hoping to hear, remember the potential risk to your baby's fetal growth as the ultimate reason you want to hold off on this eating pattern until you are no longer pregnant.

If you are at all worried about your nutrition during pregnancy, it's always in your best interest to consult with an OBGYN or registered dietician who specializes in pre and post-natal nutrition to form a plan for how you can best address any concerns.

7 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  4. Tith RM, Bilodeau-Bertrand M, Lee GE, Healy-Profitós J, Auger N. Fasting during ramadan increases risk of very preterm birth among arabic-speaking womenThe Journal of Nutrition. 2019;149(10):1826-1832. doi:10.1093/jn/nxz126

  5. Brady JM, Barnes-Davis ME, Poindexter BB. The high-risk infant. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 117.

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  7. CDC. Do Mothers Need More Calories While Breastfeeding?

By Kelly Kamenetzky
Kelly Kamenetzky is a Los Angeles-based freelance writer/editor with more than a decade of experience covering the parenting and family space. She enjoys connecting with experts in the parenting field and delivering impactful recommendations on family issues. She is also a mother of three.