Can I Fast While Pregnant?

Pregnant woman cutting vegetables

M_a_y_a / Getty Images

Intermittent fasting has recently seen an uptick in popularity as it is associated with various health benefits such as 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.

Considering how many people have jumped on the fasting bandwagon, it wouldn’t be unusual for someone who is newly pregnant to want to continue a practice that has previously reaped feel-good rewards for them. 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.

Despite its popularity, the scientific studies focused on fasting are scarce and results are mixed. The general consensus is intermittent fasting may be an effective weight-loss strategy and also have positive cognitive and cardiovascular effects; however, further research is necessary to confirm it.

“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 significant weight loss occurs 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.

Premature babies are 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, it can also lead to preterm birth. Just like it's possible to develop gestational diabetes (involving high blood sugar) during pregnancy, you can also end up with low blood sugar which can lead to hypoglycemia.

“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 to eat an extra 300 nutrient-dense calories each day 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. "This is not good for an unborn baby and may lead to poor growth and what is known as IUGR, or intrauterine growth restriction, which may lead to stillbirth."

Extra Weight Gain

If done incorrectly, intermittent fasting can actually lead to weight gain. This can occur when a person doesn't consume enough calories during their non-fasting hours or days.

"The problem with fasting, especially during pregnancy, is that the body will sense it is starving, and therefore will try to keep sugar around longer, having the opposite effect that is intended," says Dr. Adashek. "Although the person who is pregnant may consume fewer calories in a 24 hour period, the body will sense that it is starving and, therefore, less weight loss will occur."

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 consume an extra 330 to 400 kilocalories per day, per the CDC.

It's also suggested to refrain from fasting immediately after giving birth, as the body needs time to recover from the demands of pregnancy. Anyone interested in returning to fasting postpartum should seek advice from a medical professional to address concerns and potential complications.

Pregnancy Safe Alternatives

There are a plethora of healthy, productive ways to feel good in your body during pregnancy. If you want to make the most of these nine months, it starts with proper nutrition and listening to your intuition.

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 diet during pregnancy, it's always in your best interest to consult with an OBGYN, midwife, or healthcare provider to form a plan for how you can best address any concerns.

Was this page helpful?
10 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.
  1. National Institute on Aging. Research on intermittent fasting shows health benefits. Updated February 27, 2020.

  2. U.S. National Library of Medicine. Eating right during pregnancy. MedlinePlus. Reviewed October 5, 2020.

  3. Harris L, Hamilton S, Azevedo LB, et al. Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis. JBI Database System Rev Implement Rep. 2018;16(2):507-547. doi:10.11124/JBISRIR-2016-003248

  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. Reviewed October 2, 2020.

  6. Persson B, Hansson U. Hypoglycaemia in pregnancyBaillieres Clin Endocrinol Metab. 1993;7(3):731-739. 1993 Jul;7(3):731-9. doi: 10.1016/s0950-351x(05)80216-2.

  7. Herrmann TS, Siega-Riz AM, Hobel CJ, Aurora C, Dunkel-Schetter C. Prolonged periods without food intake during pregnancy increase risk for elevated maternal corticotropin-releasing hormone concentrations. Am J Obstet Gynecol. 2001;185(2):403-412. doi:10.1067/mob.2001.115863.

  8. U.S. National Library of Medicine. Intrauterine growth restriction. MedlinePlus. Reviewed December 2, 2020.

  9. Templeman I, Smith HA, Chowdhury E, et al. A randomized controlled trial to isolate the effects of fasting and energy restriction on weight loss and metabolic health in lean adults. Science Translational Medicine. 2021;13(598). doi: 10.1126/scitranslmed.abd8034.

  10. Centers for Disease Control and Prevention. Maternal Diet. September 2, 2021.