Can I Use Intermittent Fasting While Breastfeeding?

Woman nursing her infant

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Putting on weight during pregnancy is necessary to support a developing baby. Many postpartum parents feel ready to shed those extra pounds after giving birth and "get their body back." You should always feel proud of your postpartum body and everything it has achieved, and you should never rush the process of losing pregnancy weight.

That being said, it's normal to want to lose weight postpartum. If part of feeling healthy and confident to you means losing some weight, you may be considering intermittent fasting.

In a nutshell, intermittent fasting is eating during set windows of time and not eating (fasting) during set windows of time. For example, you may eat during the first eight hours of the day and fast for the remaining 16. Intermittent fasting works for many people, but if you are breastfeeding, you may wonder whether this practice is safe.

Not enough studies have been done on intermittent fasting while breastfeeding to say for sure whether it is OK to do, but we do know that your body has certain needs when you are lactating that intermittent fasting may impede upon. So if you do choose to try it, it's important to be aware of these needs and to prioritize them, as well as consult with a healthcare provider before starting.

Most importantly, lactation is considered successful if your baby is gaining weight. If your baby is not gaining enough weight or loses weight, you should not try intermittent fasting.

Intermittent Fasting While Breastfeeding

Intermittent fasting can be safe during breastfeeding but only if you are able to meet your caloric, nutritional, and fluid requirements. If you find that you cannot, or you experience unpleasant side effects, you should stop intermittent fasting.

"Intermittent fasting for weight loss while breastfeeding will not harm the baby as long as you continue regular feedings," says Bruce K. Young, MD, an internationally known leader and innovator in obstetrics and gynecology. "However, you may experience dizziness, nausea, or upset stomach pains, and should always be sure to drink lots of water. If these symptoms occur you should stop the fasting."

Safe Practices for Intermittent Fasting

Intermittent fasting is only safe while breastfeeding if you are able to consume about 2,300 to 2,500 nutritious calories daily, get enough nutrients, especially protein, carbohydrates, and fat, and drink enough fluids, especially throughout the fasting window.

Additionally, you want to make sure that your baby is gaining enough weight and you don't experience any unpleasant side effects like fainting or nausea.

While there is not a substantial amount of research specifically about using intermittent fasting while breastfeeding, we can use data collected on nursing parents who fast during Ramadan, a sacred month in Islam, to learn about how fasting may affect breastfeeding parents and their nurslings.

In a survey of breastfeeding moms in Turkey who fasted during Ramadan, the women reported having a lower milk supply while fasting. However, another study in Gambia measured milk supply before and during Ramadan and found no difference.

The Gambia study did find that breastmilk of women who fasted changed its content and that the women did not consume enough fluids. This indicates that fasting while breastfeeding may not be safe for extended periods like dawn to dusk during Ramadan. It also emphasizes the importance of consuming plenty of extra fluids if you do fast while nursing.

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

Safety Precautions

If you want to try intermittent fasting while breastfeeding, you will need to pay attention to more details than if you were not nursing. Your nutritional needs should be your first priorty.

Consuming Enough Calories

Nursing parents require an additional 450 to 500 kilocalories per day, compared to what a healthy, non-pregnant person requires. This means that you need to consume about 2,300 to 2,500 calories daily all within your eating window.

"While you are breastfeeding, you need adequate calories to maintain your supply," notes Ana Reisdorf, MS, RD, a registered dietician for Wellness Verge. "When you restrict your eating window, it can be difficult to get the calories you need."

Drinking Enough Fluids

While breastfeeding, you need to drink about 16 cups of water each day. That's double what you'd need if you weren't breastfeeding! This means you will need to be drinking water all day long, including throughout your fasting window. But don't worry—water is completely fine (and recommended!) during fasting.

Nutritional Deficit

Fasting or not, it's important to get enough nutrients while you are breastfeeding. You especially need to consume extra protein, carbohydrates, and fat, and you can't get these nutrients in a prenatal vitamin.

"[If you are fasting], you might be missing out on important nutrients that you and your baby need," explains Dr. Reisdorph. "It is difficult to meet all your nutrient needs [while fasting]."

If you decide to try intermittent fasting while you are breastfeeding, Dr. Young emphasizes the importance of eating a wide variety of fruits, vegetables, lean meats, and both enriched staple grain and whole-grain foods.

Stress

Fasting increases the production of cortisol, the hormone associated with stress. Virtually all new parents suffer from sleep deprivation during the early months of their babies' lives, and sleep deprivation will also spike cortisol. "If you are trying to do intermittent fasting without sleep, you are setting yourself up for significant side effects of out-of-whack cortisol and hormones," cautions Dr. Reisdorph. 

Stress may also decrease milk production. To avoid excessive stress and anxiety, you may want to choose a longer eating window or skip intermittent fasting altogether.

When Can I Resume Intermittent Fasting?

Intermittent fasting can be done while breastfeeding, but it needs to be done very carefully. If you find that you can't get enough calories, nutrients, or fluids while intermittent fasting, you may choose to hold off until it's safer for you to try.

It's not just about whether or not you're still nursing, either. You want to be getting solid sleep overnight so that intermittent fasting doesn't take an extra toll on your stress hormones. "I would recommend resuming intermittent fasting [after] your baby is completely weaned and has a relatively regular sleep schedule," notes Dr. Reisdorph.

Breastfeeding Safe Alternatives

If you choose not to intermittently fast, there are other ways to safely stay fit and healthy while breastfeeding.

Cardiovascular Exercise

It is safe and healthy to exercise while breastfeeding. Going on a stroller run or hopping on your exercise bike during nap time can help you get back into shape while also boosting your mood.

Eat More Healthy Fats

If you're concerned about calorie restriction while breastfeeding, focus instead on eating nutritious foods! Consuming healthy fats like olive oil, nuts, seeds, avocado, and fatty fish like salmon or herring in place of saturated or trans fats will help keep your body in tip-top shape while you are breastfeeding. Unsaturated fats are beneficial to your nursing baby as well.

Focus on Your Sleep Hygeine

Having a baby throws your sleep hygiene out the window. Sleep deprivation spikes the stress hormone cortisol, which may make it easier to gain weight and harder to lose it. Getting enough sleep each night is easier said than done with an infant in your care, but prioritizing your rest whenever you can help you stay in shape and feeling good.

A Word From Verywell

Not enough research has been done to say for sure whether intermittent fasting is safe to do while breastfeeding. What we do know is that breastfeeding parents require an additional 450 to 500 kilocalories per day. They also need to be getting the proper nutrients to support postpartum recovery and to properly nourish their baby. Increased fluids are also vital for both nurser and nursling.

Intermittent fasting might impede your ability to get enough calories, proper nutrients, or enough fluids. The only way that intermittent fasting can be safe is if you can fit your required calories and nutrients into your eating window while consuming lots of fluids throughout both the eating window and the fasting window.

Most important of all is whether your baby is gaining weight. If a healthcare provider expresses any concern about this, you should not be using intermittent fasting.

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